From Reuters Health Information
NEW YORK (Reuters Health) Aug 20 - Ambulatory blood pressure testing suggests that people with passive domestic or work exposure to tobacco smoke are at increased risk of masked hypertension, Greek researchers report in the August issue of the American Journal of Hypertension.
"Our findings," investigator Dr. Costas Thomopoulos told Reuters Health, "demonstrate that passive smoking may be a 'hidden partner' of out-of-clinic hypertension and especially of masked hypertension."
Dr. Thomopoulos of Elena Venizelou Hospital, Athens, and colleagues came to this conclusion after studying 154 patients with regular passive smoke exposure and another 100 without exposure. All were self-referred to the hospital's outpatient hypertensive unit for blood pressure evaluation.
The subjects had blood pressure measures taken on 3 separate visits to the clinic and also underwent 24-hour ambulatory monitoring on a work day.
Compared to those who were not exposed, the passive smokers showed higher 24 hour systolic BP (126 versus 122 mm/Hg), diastolic BP (89 versus 84 mm/Hg) and clinic heart rate (79 versus 73 beats per minute) (p<0.05 for all). In addition, passive smokers had a higher prevalence of masked hypertension (23% versus 8%; p<0.01).
On multivariate analysis, passive smoking was an independent predictor of masked hypertension, as were weekly duration and intensity of passive smoke exposure, younger age, clinic heart rate, low physical activity, and standing/sitting differences in diastolic BP and heart rate.
Further studies are needed, Dr. Thomopoulos said, but these findings point in "the direction of including passive smoking evaluation in (routine) clinical practice."
Am J Hypertens 2009;22:853-859.
Saturday, September 5, 2009
Friday, September 4, 2009
Only Three Cigarettes a Day Significantly Increases Cardiovascular Disease Risk
From Heartwire
Martha Kerr
September 3, 2009 (Provo, Utah) — Exposure to relatively low levels of fine particulate matter (PM) significantly increases the risk of cardiovascular disease [1]. The risk trajectory levels off with higher levels of exposure, researchers report, in a study published online August 31, 2009 in Circulation. The study will appear in the September 15 issue.
Risk of cardiovascular disease increased 64% by smoking three cigarettes a day. Risk doubled by smoking a pack a day, according to data on more than one million adults prospectively collected by the American Cancer Society, as part of the Cancer Prevention Study II of 1982.
Using this database, Dr C Arden Pope (Brigham Young University Provo, UT) and colleagues calculated adjusted relative risks of mortality according to an estimated average daily dose of fine PM from active cigarette-smoke inhalation, as well as the PM doses from secondhand cigarette-smoke exposure and from exposure to air pollution.
"There were substantially increased cardiovascular mortality risks at very low levels of active cigarette smoking and smaller but significant excess risks even at the much lower exposure levels associated with secondhand cigarette smoke and ambient air pollution," the researchers report.
"The results indicate that it is fundamentally implausible that the relationship between cardiovascular mortality and fine particulate pollution from cigarette smoke and ambient air pollution can be characterized as linked by a simple linear dose-response relationship," the authors write. "Rather, our results suggest that the exposure-response function is relatively steep at very low levels of exposure, flattening out at high exposure levels."
Pope and colleagues note several limitations of the study, among them the large exposure gap between ambient air pollution, secondhand-smoke exposure, and active smoking. And, the authors say, there are no prospective cohort or related studies of long-term exposure across the range of exposure that would fill this gap.
Even with its limitations, the study findings have important public-health implications, Pope's team comments. Most studies of the effects of fine PM on cardiovascular disease risk have been conducted in areas where the annual average PM concentrations rarely exceed 30 µg/m3. Recent estimates indicate average concentrations of particulate air pollution in urban areas of China, India, and other developing countries often exceed 100 µg/m3
Martha Kerr
September 3, 2009 (Provo, Utah) — Exposure to relatively low levels of fine particulate matter (PM) significantly increases the risk of cardiovascular disease [1]. The risk trajectory levels off with higher levels of exposure, researchers report, in a study published online August 31, 2009 in Circulation. The study will appear in the September 15 issue.
Risk of cardiovascular disease increased 64% by smoking three cigarettes a day. Risk doubled by smoking a pack a day, according to data on more than one million adults prospectively collected by the American Cancer Society, as part of the Cancer Prevention Study II of 1982.
Using this database, Dr C Arden Pope (Brigham Young University Provo, UT) and colleagues calculated adjusted relative risks of mortality according to an estimated average daily dose of fine PM from active cigarette-smoke inhalation, as well as the PM doses from secondhand cigarette-smoke exposure and from exposure to air pollution.
"There were substantially increased cardiovascular mortality risks at very low levels of active cigarette smoking and smaller but significant excess risks even at the much lower exposure levels associated with secondhand cigarette smoke and ambient air pollution," the researchers report.
"The results indicate that it is fundamentally implausible that the relationship between cardiovascular mortality and fine particulate pollution from cigarette smoke and ambient air pollution can be characterized as linked by a simple linear dose-response relationship," the authors write. "Rather, our results suggest that the exposure-response function is relatively steep at very low levels of exposure, flattening out at high exposure levels."
Pope and colleagues note several limitations of the study, among them the large exposure gap between ambient air pollution, secondhand-smoke exposure, and active smoking. And, the authors say, there are no prospective cohort or related studies of long-term exposure across the range of exposure that would fill this gap.
Even with its limitations, the study findings have important public-health implications, Pope's team comments. Most studies of the effects of fine PM on cardiovascular disease risk have been conducted in areas where the annual average PM concentrations rarely exceed 30 µg/m3. Recent estimates indicate average concentrations of particulate air pollution in urban areas of China, India, and other developing countries often exceed 100 µg/m3
Hong Kong Health Care Workers Leery of H1N1 Vaccine
From Reuters Health Information
NEW YORK (Reuters Health) Aug 26 - Even though testing has so far raised no "red flags" regarding safety of vaccines against the novel H1N1 influenza virus, surveys and focus groups show that healthcare workers and members of the public may be leery of being inoculated when supplies become available this fall.
Writing in the August 26 issue of BMJ Online First, Dr. Paul K. S. Chan and associates at the Chinese University of Hong Kong note that "in nearly all countries with a (pandemic) preparedness plan, healthcare workers are listed as the priority group for mass vaccination."
In May of this year when the WHO pandemic influenza alert level had been raised to phase 5, the researchers distributed 810 questionnaires to public hospital workers, primarily doctors and nurses.
A tally of the 389 questionnaires that were returned indicated that less than half (48%) intended to accept pre-pandemic H1N1 vaccination. The most common reason for refusal was worry over side effects, follow by questions about the vaccine's efficacy and the conviction that it was "not yet the right time to be vaccinated."
"This is particularly surprising in a city where the SARS outbreak had such a huge impact," Dr. Chan's team points out.
The strongest associations with willingness to be vaccinated, the report indicates, were a history of seasonal flu vaccination and the perception that they were likely to be infected.
In a linked commentary, Dr. Rachel Jordan, from the University of Birmingham, and Dr. Andrew Hayward, from the University College of London, advise that in order to maximize vaccine uptake, "use of convenient mobile systems, monitoring and feedback systems, and 'opt-out' systems (where healthcare workers need to indicate their reasons for not accepting the vaccine) show promise."
In a separate article published online in the Emerging Health Threats Journal, Dr. Natalie Henrich of the University of British Columbia and Dr. Bev J. Holmes at Simon Fraser University, both in Vancouver, describe findings from 11 focus groups conducted with the public in Vancouver, Canada, in 2006 and 2007 to explore their willingness to use novel vaccines in a pandemic.
The researchers asked the 85 participants how willing they would be to accept a new vaccine in the event of a pandemic. Very few people said they or their children would definitely get vaccinated, the authors report. Participants' concerns centered around the risk of infection versus the risks involved in using newly developed vaccines.
"Participants were hesitant to use the novel vaccines (due to) concern that unsafe pharmaceuticals may be rushed to market during the health crisis," the authors said.
Instead, many individuals believed they could protect themselves through their own behavior, including frequent handwashing, staying away from crowded places and sick people, and eating well to maintain their strong immune system.
BMJ 2009;339:b3391.
Emerging Health Threats Journal 2009.
NEW YORK (Reuters Health) Aug 26 - Even though testing has so far raised no "red flags" regarding safety of vaccines against the novel H1N1 influenza virus, surveys and focus groups show that healthcare workers and members of the public may be leery of being inoculated when supplies become available this fall.
Writing in the August 26 issue of BMJ Online First, Dr. Paul K. S. Chan and associates at the Chinese University of Hong Kong note that "in nearly all countries with a (pandemic) preparedness plan, healthcare workers are listed as the priority group for mass vaccination."
In May of this year when the WHO pandemic influenza alert level had been raised to phase 5, the researchers distributed 810 questionnaires to public hospital workers, primarily doctors and nurses.
A tally of the 389 questionnaires that were returned indicated that less than half (48%) intended to accept pre-pandemic H1N1 vaccination. The most common reason for refusal was worry over side effects, follow by questions about the vaccine's efficacy and the conviction that it was "not yet the right time to be vaccinated."
"This is particularly surprising in a city where the SARS outbreak had such a huge impact," Dr. Chan's team points out.
The strongest associations with willingness to be vaccinated, the report indicates, were a history of seasonal flu vaccination and the perception that they were likely to be infected.
In a linked commentary, Dr. Rachel Jordan, from the University of Birmingham, and Dr. Andrew Hayward, from the University College of London, advise that in order to maximize vaccine uptake, "use of convenient mobile systems, monitoring and feedback systems, and 'opt-out' systems (where healthcare workers need to indicate their reasons for not accepting the vaccine) show promise."
In a separate article published online in the Emerging Health Threats Journal, Dr. Natalie Henrich of the University of British Columbia and Dr. Bev J. Holmes at Simon Fraser University, both in Vancouver, describe findings from 11 focus groups conducted with the public in Vancouver, Canada, in 2006 and 2007 to explore their willingness to use novel vaccines in a pandemic.
The researchers asked the 85 participants how willing they would be to accept a new vaccine in the event of a pandemic. Very few people said they or their children would definitely get vaccinated, the authors report. Participants' concerns centered around the risk of infection versus the risks involved in using newly developed vaccines.
"Participants were hesitant to use the novel vaccines (due to) concern that unsafe pharmaceuticals may be rushed to market during the health crisis," the authors said.
Instead, many individuals believed they could protect themselves through their own behavior, including frequent handwashing, staying away from crowded places and sick people, and eating well to maintain their strong immune system.
BMJ 2009;339:b3391.
Emerging Health Threats Journal 2009.
Thursday, September 3, 2009
Importance of Exercise and Physical Activity in Older Adults Reviewed
From Medscape Medical News CME
Laurie Barclay, Désirée Lie,
July 8, 2009 — The American College of Sports Medicine has issued a position stand providing an overview of issues critical to understanding the importance of exercise and physical activity in older adult populations. The review and guidelines are published in the July issue of Medicine & Science in Sports & Exercise.
"The 2008 Physical Activity Guidelines for Americans affirms that regular physical activity reduces the risk of many adverse health outcomes," write Wojtek J. Chodzko-Zajko, PhD, and colleagues from the American College of Sports Medicine. "The guidelines state that all adults should avoid inactivity, that some physical activity is better than none, and that adults who participate in any amount of physical activity gain some health benefits. However, the guidelines emphasize that for most health outcomes, additional benefits occur as the amount of physical activity increases through higher intensity, greater frequency, and/or longer duration."
The reviewers conclude that no amount of physical activity can stop biological aging but that evidence to date affirms that by limiting the development and progression of chronic disease and disabling conditions, regular exercise can reduce the physiologic harms of an otherwise sedentary lifestyle and improve active life expectancy. Older adults who engage in regular exercise may also experience significant psychological and cognitive benefits.
The position stand recommends that all older adults participate in regular physical activity and avoid an inactive lifestyle and that exercise prescription for older adults include aerobic, muscle-strengthening, and flexibility exercises
Benefits of Physical Activity and Exercise
The following are some specific evidence statements regarding the benefits of physical activity and exercise, and their accompanying level of evidence rating(see "Note" at end of article for explanation of the ratings):
Vigorous, long-term participation in aerobic exercise training (AET) improves cardiovascular reserve and skeletal muscle adaptations, allowing trained older persons to sustain a submaximal exercise load with less cardiovascular stress and muscular fatigue than their untrained peers. Prolonged AET may also reduce age-related accumulation of central body fat, thereby protecting the heart (level of evidence, B).
Prolonged participation in resistance exercise training (RET) increases muscle and bone mass and strength to a greater extent vs AET (level of evidence, B).
In healthy middle-aged and older adults, AET programs of sufficiently intense (≥ 60% of pretraining VO2max), frequency, and length (≥ 3 days/week for ≥ 16 weeks) may significantly improve VO2max (level of evidence, A).
In healthy middle-aged and older adults, 3 months or more of moderate-intensity AET are associated with cardiovascular adaptations which are apparent both at rest and in response to acute dynamic exercise (level of evidence, A/B).
Moderate-intensity AET has been shown to reduce total body fat, but not fat-free mass, in overweight middle-aged and older adults (level of evidence, A/B).
Beneficial metabolic changes associated with AET include improved glycemic control and clearance of postprandial lipids, as well as preferential utilization of fat during submaximal exercise (level of evidence, B).
In postmenopausal women, AET may counteract age-related decreases in bone mineral density (level of evidence, B).
RET may markedly increase strength and muscular power in older adults (level of evidence, A).
Older and younger adults have similar age-related increases in muscle quality, and these increases do not appear to be sex specific (level of evidence, B).
Improvements in muscular endurance have been reported after RET using moderate- to higher-intensity protocols, but not lower-intensity RET, and may improve muscular endurance (level of evidence, C).
Although the effect of exercise on physical function is poorly understood and may not be linear, RET may improve walking, chair stand, and balance activities (level of evidence, C/D).
Older adults who regularly take part in moderate- or high-intensity RET may have increased fat-free mass, decreased total body fat mass, and other beneficial changes in body composition (level of evidence, B/C).
Compared with sedentary control subjects, adults who participate in high-intensity RET have maintained or improved bone mineral density, with a direct relationship between muscle and bone adaptations (level of evidence, B).
Evidence is mixed regarding the effect of RET on metabolic variables (level of evidence, B/C).
In populations at increased risk of falling, multimodal exercise, including strength and balance exercises, and tai chi may decrease the risk for noninjurious and sometimes injurious falls (level of evidence, C).
Few controlled studies have evaluated the effect of flexibility exercise on range of motion in older adults (level of evidence, D).
Regular exercise and physical activity are linked to significant improvements in overall psychological well-being, possibly via effects on self-concept and self-esteem. Physical fitness and AET are linked to a lower risk for clinical depression or anxiety (level of evidence, A/B).
Cardiovascular fitness and higher levels of physical activity lower the risk for cognitive decline and dementia, based on epidemiologic studies. In experimental studies, AET and RET, alone or especially combined, improve some measures of cognitive functioning, especially those requiring executive control, in previously sedentary older adults (level of evidence, A/B).
Physical activity appears to be linked to some aspects of quality of life, but the precise nature of the relationship is unclear (level of evidence, D).
High-intensity RET is effective for treating clinical depression. Additional research should address the optimal intensity and frequency of RET needed to elicit specific improvements in other measures of psychological health and well-being (level of evidence, A/B).
"A combination of AET and RET activities seems to be more effective than either form of training alone in counteracting the detrimental effects of a sedentary lifestyle on the health and functioning of the cardiovascular system and skeletal muscles," the authors of the position stand conclude. "Although there are clear fitness, metabolic, and performance benefits associated with higher-intensity exercise training programs in healthy older adults, it is now evident that such programs do not need to be of high intensity to reduce the risks of developing chronic cardiovascular and metabolic disease. However, the outcome of treatment of some established diseases and geriatric syndromes is more effective with higher-intensity exercise (e.g., type 2 diabetes, clinical depression, osteopenia, sarcopenia, muscle weakness)."
Med Sci Sports Exerc. 2009;41:1510-1530.
Laurie Barclay, Désirée Lie,
July 8, 2009 — The American College of Sports Medicine has issued a position stand providing an overview of issues critical to understanding the importance of exercise and physical activity in older adult populations. The review and guidelines are published in the July issue of Medicine & Science in Sports & Exercise.
"The 2008 Physical Activity Guidelines for Americans affirms that regular physical activity reduces the risk of many adverse health outcomes," write Wojtek J. Chodzko-Zajko, PhD, and colleagues from the American College of Sports Medicine. "The guidelines state that all adults should avoid inactivity, that some physical activity is better than none, and that adults who participate in any amount of physical activity gain some health benefits. However, the guidelines emphasize that for most health outcomes, additional benefits occur as the amount of physical activity increases through higher intensity, greater frequency, and/or longer duration."
The reviewers conclude that no amount of physical activity can stop biological aging but that evidence to date affirms that by limiting the development and progression of chronic disease and disabling conditions, regular exercise can reduce the physiologic harms of an otherwise sedentary lifestyle and improve active life expectancy. Older adults who engage in regular exercise may also experience significant psychological and cognitive benefits.
The position stand recommends that all older adults participate in regular physical activity and avoid an inactive lifestyle and that exercise prescription for older adults include aerobic, muscle-strengthening, and flexibility exercises
Benefits of Physical Activity and Exercise
The following are some specific evidence statements regarding the benefits of physical activity and exercise, and their accompanying level of evidence rating(see "Note" at end of article for explanation of the ratings):
Vigorous, long-term participation in aerobic exercise training (AET) improves cardiovascular reserve and skeletal muscle adaptations, allowing trained older persons to sustain a submaximal exercise load with less cardiovascular stress and muscular fatigue than their untrained peers. Prolonged AET may also reduce age-related accumulation of central body fat, thereby protecting the heart (level of evidence, B).
Prolonged participation in resistance exercise training (RET) increases muscle and bone mass and strength to a greater extent vs AET (level of evidence, B).
In healthy middle-aged and older adults, AET programs of sufficiently intense (≥ 60% of pretraining VO2max), frequency, and length (≥ 3 days/week for ≥ 16 weeks) may significantly improve VO2max (level of evidence, A).
In healthy middle-aged and older adults, 3 months or more of moderate-intensity AET are associated with cardiovascular adaptations which are apparent both at rest and in response to acute dynamic exercise (level of evidence, A/B).
Moderate-intensity AET has been shown to reduce total body fat, but not fat-free mass, in overweight middle-aged and older adults (level of evidence, A/B).
Beneficial metabolic changes associated with AET include improved glycemic control and clearance of postprandial lipids, as well as preferential utilization of fat during submaximal exercise (level of evidence, B).
In postmenopausal women, AET may counteract age-related decreases in bone mineral density (level of evidence, B).
RET may markedly increase strength and muscular power in older adults (level of evidence, A).
Older and younger adults have similar age-related increases in muscle quality, and these increases do not appear to be sex specific (level of evidence, B).
Improvements in muscular endurance have been reported after RET using moderate- to higher-intensity protocols, but not lower-intensity RET, and may improve muscular endurance (level of evidence, C).
Although the effect of exercise on physical function is poorly understood and may not be linear, RET may improve walking, chair stand, and balance activities (level of evidence, C/D).
Older adults who regularly take part in moderate- or high-intensity RET may have increased fat-free mass, decreased total body fat mass, and other beneficial changes in body composition (level of evidence, B/C).
Compared with sedentary control subjects, adults who participate in high-intensity RET have maintained or improved bone mineral density, with a direct relationship between muscle and bone adaptations (level of evidence, B).
Evidence is mixed regarding the effect of RET on metabolic variables (level of evidence, B/C).
In populations at increased risk of falling, multimodal exercise, including strength and balance exercises, and tai chi may decrease the risk for noninjurious and sometimes injurious falls (level of evidence, C).
Few controlled studies have evaluated the effect of flexibility exercise on range of motion in older adults (level of evidence, D).
Regular exercise and physical activity are linked to significant improvements in overall psychological well-being, possibly via effects on self-concept and self-esteem. Physical fitness and AET are linked to a lower risk for clinical depression or anxiety (level of evidence, A/B).
Cardiovascular fitness and higher levels of physical activity lower the risk for cognitive decline and dementia, based on epidemiologic studies. In experimental studies, AET and RET, alone or especially combined, improve some measures of cognitive functioning, especially those requiring executive control, in previously sedentary older adults (level of evidence, A/B).
Physical activity appears to be linked to some aspects of quality of life, but the precise nature of the relationship is unclear (level of evidence, D).
High-intensity RET is effective for treating clinical depression. Additional research should address the optimal intensity and frequency of RET needed to elicit specific improvements in other measures of psychological health and well-being (level of evidence, A/B).
"A combination of AET and RET activities seems to be more effective than either form of training alone in counteracting the detrimental effects of a sedentary lifestyle on the health and functioning of the cardiovascular system and skeletal muscles," the authors of the position stand conclude. "Although there are clear fitness, metabolic, and performance benefits associated with higher-intensity exercise training programs in healthy older adults, it is now evident that such programs do not need to be of high intensity to reduce the risks of developing chronic cardiovascular and metabolic disease. However, the outcome of treatment of some established diseases and geriatric syndromes is more effective with higher-intensity exercise (e.g., type 2 diabetes, clinical depression, osteopenia, sarcopenia, muscle weakness)."
Med Sci Sports Exerc. 2009;41:1510-1530.
High-Carb, High-Fat Diets Superior to High-Protein Diets in Improving Cognitive Performance
From Medscape Medical News
Deborah Brauser
September 1, 2009 — Diets high in carbohydrates or fat can lead to significantly better cognitive-performance and inflight-testing scores in pilots than diets high in protein, according to results reported in a poster presentation at the Military Health Research Forum (MHRF) 2009 in Kansas City, Missouri.
In addition, a high-carbohydrate diet helped study pilots sleep better, and a high-fat diet appeared to lead to significantly faster short-term memory.
"We started out thinking that the high-protein diet would lead to being the sharpest afterward," said colead investigator Glenda Lindseth, RN, PhD, licensed registered dietician and professor of nursing at the University of North Dakota (UND) in Grand Forks. "But we were surprised by our findings that it was actually the high-carb or high-fat diets that were the best. Eating a diet that's high in protein just isn't going to help you perform optimally."
"As a retired air-force pilot and a pilot for over 30 years, I believe this type of study is definitely needed," said the other colead author, Paul Lindseth, PhD, professor of aviation and associate dean at the UND Odegard School of Aerospace Sciences. "This is important for pilots in the military and in combat situations, where they need to be sharp and alert."
The Lindseths report that human error has been implicated in 70% to 80% of civil- and military-aviation accidents and in up to 91% of general-aviation accidents. In addition, lack of proper nutrition was rated as the top stressor in the daily lives of professional airline pilots.
Little Research on Diet and Cognition
There is currently little research on the potential connection between dietary intake and cognition. So in this study, the investigators sought to compare diets high in carbohydrates, fat, and protein to test their effects on cognition, flight performance, and sleep patterns.
A total of 45 pilots (mean age, 20.8 years; 87% male) from the UND commercial-aviation program were enrolled in this 14-week repeated-measures crossover trial.
During the first week, participants were randomized to receive 1 of 4 diets (3 full meals and 2 snacks) for 4 days: a diet high in carbohydrates, a diet high in fat, a diet high in protein, or a control diet. After a 2-week "phase-out" period, all pilots then randomly received a different study diet. This process was repeated until all pilots had received all 4 diets.
"We made sure that each pilot, no matter which of the study plans we gave them, got what would be considered a well-balanced diet, within 95% of the US recommended daily allowances for all of the micronutrients," explained Glenda Lindseth. In addition, the pilots were tested to make sure they received the number of calories required to sustain their weight.
Worse Performance With High-Protein Diet
Flight performance scores were determined using a GATT 2 full-motion flight simulator. The Sternberg item-recognition test and the Vandenberg mental-rotation test were used to evaluate cognitive function. Sleep patterns were measured with the Actiwatch sleep watch.
Results showed that overall flight-performance scores for the pilots consuming a high-protein diet were significantly worse (P < 05) than for those consuming a high-carbohydrate or a high-fat diet. A hierarchical regression analysis indicated that this was due in part to dietary protein intakes, serotonin levels, and irritability scores.
In addition, high-carbohydrate diets produced shorter sleep latencies than the other diets, especially the control diet (P < .03). In fact, the researchers found that if the pilots ate the high-carbohydrate diet, they seemed to sleep better, fall asleep quicker, and wake up less often.
The response time on the Sternberg test of short-term memory was significantly faster for participants who ate the high-fat diet (P < .05) than for those who ate the protein and control diets, especially at higher memory loads. No significant impact was observed on the Vandenberg test.
"We're certainly not saying you always have to eat high fat," said Glenda Lindseth. "The take-away message is that a diet that is well balanced and has a lot of carbohydrates and a reasonable amount of fat in it is best for pilots to perform well cognitively."
"These results can make significant contributions to understanding the effects of diet on cognition and performance and may, therefore, decrease the number of errors due to human factors for the war fighter," she added. The investigators are planning a follow-up study to confirm their findings.
Findings Likely Generalizeable
In an interview with Medscape Psychiatry, Karen Tountas, PhD, MHRF conference chair and the event's peer-reviewed medical research program manager, said: "I think this is a very exciting study. They've focused on working with pilots but anything we can find out about diet and its relationship to cognition [will likely] translate across all people. [This study] does open up avenues of more questions to be asked." Dr. Tountas was not associated with the trial.
She said that others reading these results should take into consideration who their particular patients are. "There are a lot of other different end points. Is it cognition that [the clinician] is looking at? Is it weight? Is it a combination of those 2? I think that it would be important for [clinicians] to get a broader picture of that before making a decision for their own patient population."
"We know the brain's primary source of energy is glucose — that is sugar, just straight sugar," Captain E. Melissa Kaime, MD, director of the Congressionally Directed Medical Research Programs (CDMRP), part of the US Army Medical Research and Materiel Command, told Medscape Psychiatry.
"In some ways it shouldn't surprise us that a diet high in carbohydrates is good for the brain because that's the glucose it needs. But we all know that there are other problems in society too, such as an obesity epidemic. So we want to certainly feed the brain but we don't want to overfeed it or the rest of the body." Captain Kaime was not involved in the study.
"Pilots use higher executive-functioning parts of their brains, and this study was testing these highly trained pilots at their maximum cognitive stress," added Captain Kaime.
"This is the first look at a new way of science, of looking to see: What does the brain need? So the next step is going to be: What dose now? What schedule? If you need glucose, is it 10 minutes before the stress test of the brain or is it a continuous diet of glucose? Like all good studies, this one brings up more questions than it answers."
"We're trying so hard to keep people healthy and we want the magic bullet — the 1 pill or the 1 vaccine that fixes everything." Captain Kaime said that this study is just 1 more that says the solution "is in your diet. And that is actually good news. Because if the solutions are . . . common sense and practical and available, [something] that you don't have to go out and buy with a prescription and that is at your fingertips anyway, that just makes it all the more powerful."
This study was funded by the CDMRP of the US Department of Defense. The Lindseths, Dr. Tountas, and Captain Kaime have disclosed no relevant financial relationships.
Military Health Research Forum (MHRF) 2009: Abstract P16-9. Presented September 1, 2009.
Deborah Brauser
September 1, 2009 — Diets high in carbohydrates or fat can lead to significantly better cognitive-performance and inflight-testing scores in pilots than diets high in protein, according to results reported in a poster presentation at the Military Health Research Forum (MHRF) 2009 in Kansas City, Missouri.
In addition, a high-carbohydrate diet helped study pilots sleep better, and a high-fat diet appeared to lead to significantly faster short-term memory.
"We started out thinking that the high-protein diet would lead to being the sharpest afterward," said colead investigator Glenda Lindseth, RN, PhD, licensed registered dietician and professor of nursing at the University of North Dakota (UND) in Grand Forks. "But we were surprised by our findings that it was actually the high-carb or high-fat diets that were the best. Eating a diet that's high in protein just isn't going to help you perform optimally."
"As a retired air-force pilot and a pilot for over 30 years, I believe this type of study is definitely needed," said the other colead author, Paul Lindseth, PhD, professor of aviation and associate dean at the UND Odegard School of Aerospace Sciences. "This is important for pilots in the military and in combat situations, where they need to be sharp and alert."
The Lindseths report that human error has been implicated in 70% to 80% of civil- and military-aviation accidents and in up to 91% of general-aviation accidents. In addition, lack of proper nutrition was rated as the top stressor in the daily lives of professional airline pilots.
Little Research on Diet and Cognition
There is currently little research on the potential connection between dietary intake and cognition. So in this study, the investigators sought to compare diets high in carbohydrates, fat, and protein to test their effects on cognition, flight performance, and sleep patterns.
A total of 45 pilots (mean age, 20.8 years; 87% male) from the UND commercial-aviation program were enrolled in this 14-week repeated-measures crossover trial.
During the first week, participants were randomized to receive 1 of 4 diets (3 full meals and 2 snacks) for 4 days: a diet high in carbohydrates, a diet high in fat, a diet high in protein, or a control diet. After a 2-week "phase-out" period, all pilots then randomly received a different study diet. This process was repeated until all pilots had received all 4 diets.
"We made sure that each pilot, no matter which of the study plans we gave them, got what would be considered a well-balanced diet, within 95% of the US recommended daily allowances for all of the micronutrients," explained Glenda Lindseth. In addition, the pilots were tested to make sure they received the number of calories required to sustain their weight.
Worse Performance With High-Protein Diet
Flight performance scores were determined using a GATT 2 full-motion flight simulator. The Sternberg item-recognition test and the Vandenberg mental-rotation test were used to evaluate cognitive function. Sleep patterns were measured with the Actiwatch sleep watch.
Results showed that overall flight-performance scores for the pilots consuming a high-protein diet were significantly worse (P < 05) than for those consuming a high-carbohydrate or a high-fat diet. A hierarchical regression analysis indicated that this was due in part to dietary protein intakes, serotonin levels, and irritability scores.
In addition, high-carbohydrate diets produced shorter sleep latencies than the other diets, especially the control diet (P < .03). In fact, the researchers found that if the pilots ate the high-carbohydrate diet, they seemed to sleep better, fall asleep quicker, and wake up less often.
The response time on the Sternberg test of short-term memory was significantly faster for participants who ate the high-fat diet (P < .05) than for those who ate the protein and control diets, especially at higher memory loads. No significant impact was observed on the Vandenberg test.
"We're certainly not saying you always have to eat high fat," said Glenda Lindseth. "The take-away message is that a diet that is well balanced and has a lot of carbohydrates and a reasonable amount of fat in it is best for pilots to perform well cognitively."
"These results can make significant contributions to understanding the effects of diet on cognition and performance and may, therefore, decrease the number of errors due to human factors for the war fighter," she added. The investigators are planning a follow-up study to confirm their findings.
Findings Likely Generalizeable
In an interview with Medscape Psychiatry, Karen Tountas, PhD, MHRF conference chair and the event's peer-reviewed medical research program manager, said: "I think this is a very exciting study. They've focused on working with pilots but anything we can find out about diet and its relationship to cognition [will likely] translate across all people. [This study] does open up avenues of more questions to be asked." Dr. Tountas was not associated with the trial.
She said that others reading these results should take into consideration who their particular patients are. "There are a lot of other different end points. Is it cognition that [the clinician] is looking at? Is it weight? Is it a combination of those 2? I think that it would be important for [clinicians] to get a broader picture of that before making a decision for their own patient population."
"We know the brain's primary source of energy is glucose — that is sugar, just straight sugar," Captain E. Melissa Kaime, MD, director of the Congressionally Directed Medical Research Programs (CDMRP), part of the US Army Medical Research and Materiel Command, told Medscape Psychiatry.
"In some ways it shouldn't surprise us that a diet high in carbohydrates is good for the brain because that's the glucose it needs. But we all know that there are other problems in society too, such as an obesity epidemic. So we want to certainly feed the brain but we don't want to overfeed it or the rest of the body." Captain Kaime was not involved in the study.
"Pilots use higher executive-functioning parts of their brains, and this study was testing these highly trained pilots at their maximum cognitive stress," added Captain Kaime.
"This is the first look at a new way of science, of looking to see: What does the brain need? So the next step is going to be: What dose now? What schedule? If you need glucose, is it 10 minutes before the stress test of the brain or is it a continuous diet of glucose? Like all good studies, this one brings up more questions than it answers."
"We're trying so hard to keep people healthy and we want the magic bullet — the 1 pill or the 1 vaccine that fixes everything." Captain Kaime said that this study is just 1 more that says the solution "is in your diet. And that is actually good news. Because if the solutions are . . . common sense and practical and available, [something] that you don't have to go out and buy with a prescription and that is at your fingertips anyway, that just makes it all the more powerful."
This study was funded by the CDMRP of the US Department of Defense. The Lindseths, Dr. Tountas, and Captain Kaime have disclosed no relevant financial relationships.
Military Health Research Forum (MHRF) 2009: Abstract P16-9. Presented September 1, 2009.
Smoking Boosts Multiple Sclerosis Risk
From Medscape Medical News
Allison Gandey
September 2, 2009 — Evidence is mounting that people at risk for autoimmune disease are especially susceptible to the harmful effects of smoking, but a new study suggests that nicotine might not be the culprit.
Those who stopped smoking saw their risk decline quite quickly.
"Our study confirms that smoking cigarettes increases the risk of multiple sclerosis," lead investigator Anna Hedström, MD, from the Karolinska Institutet in Stockholm, Sweden, said during an interview. "We found that the more a person smokes, the greater the risk. But what is interesting is we found that those who stopped smoking saw their risk decline quite quickly, and some exsmokers were as healthy as people who never smoked."
But in a surprising twist, researchers found that smokeless tobacco did not increase this risk. "That's not to say it isn't bad for you," Dr. Hedström told Medscape Neurology. "Other studies have linked it to heart disease and cancer — particularly lip cancer." She suggests that carcinogens other than nicotine might be affecting the immune system.
Speaking on behalf of the Multiple Sclerosis Society of Canada, Aprile Royal, assistant vice president of clinical programs, said that "there are lots of reasons not to smoke; it is bad for anyone. But for people with multiple sclerosis or those at particular risk, smoking is especially dangerous."
She complimented the study design, in which a large sample of patients was drawn from multiple centers. The work is part of the Epidemiologic Investigation of Multiple Sclerosis — an extensive case–control study of more than 900 patients and 1800 control subjects.
Researchers report that the increased risk was apparent even among participants who had smoked moderately. They report: "We found clear evidence of a dose-response correlation between cumulative dose of smoking and the risk of developing the disease."
The increased risk for multiple sclerosis associated with cigarettes remained up to 5 years after a patient stopped smoking, but it later declined.
A study published in Neurology last month showed that people with multiple sclerosis who smoke have higher lesion volumes, more atrophy, and are at greater risk for blood–brain-barrier disruption (Neurology. 2009;73:504-510).
During a recent interview, lead author of that study, Robert Zivadinov, MD, from the University of New York School of Medicine and Biomedical Sciences in Buffalo, said: "Ours is the first study to demonstrate that smoking can promote brain-tissue injury in multiple sclerosis patients."
Autoimmune Disease and Smoking Don't Mix
The findings are similar to those of a study published in July (Arch Neurol. 2009;66:858-864). As previously reported by Medscape Neurology, investigators found that smoking contributes to rapid disease progression.
Asked for comment when the study was first published, Lily Jung, MD, from the Swedish Neuroscience Institute in Seattle, Washington, and member of the American Academy of Neurology, said that "this is just more ammunition for telling patients that to stop smoking is the easiest thing they can do to treat their multiple sclerosis."
During an interview, Dr. Hedström said she agrees. She also recommends that people with a family history of multiple sclerosis avoid smoking.
Neurology. 2009;73:696-701. Abstract
Allison Gandey
September 2, 2009 — Evidence is mounting that people at risk for autoimmune disease are especially susceptible to the harmful effects of smoking, but a new study suggests that nicotine might not be the culprit.
Those who stopped smoking saw their risk decline quite quickly.
"Our study confirms that smoking cigarettes increases the risk of multiple sclerosis," lead investigator Anna Hedström, MD, from the Karolinska Institutet in Stockholm, Sweden, said during an interview. "We found that the more a person smokes, the greater the risk. But what is interesting is we found that those who stopped smoking saw their risk decline quite quickly, and some exsmokers were as healthy as people who never smoked."
But in a surprising twist, researchers found that smokeless tobacco did not increase this risk. "That's not to say it isn't bad for you," Dr. Hedström told Medscape Neurology. "Other studies have linked it to heart disease and cancer — particularly lip cancer." She suggests that carcinogens other than nicotine might be affecting the immune system.
Speaking on behalf of the Multiple Sclerosis Society of Canada, Aprile Royal, assistant vice president of clinical programs, said that "there are lots of reasons not to smoke; it is bad for anyone. But for people with multiple sclerosis or those at particular risk, smoking is especially dangerous."
She complimented the study design, in which a large sample of patients was drawn from multiple centers. The work is part of the Epidemiologic Investigation of Multiple Sclerosis — an extensive case–control study of more than 900 patients and 1800 control subjects.
Researchers report that the increased risk was apparent even among participants who had smoked moderately. They report: "We found clear evidence of a dose-response correlation between cumulative dose of smoking and the risk of developing the disease."
The increased risk for multiple sclerosis associated with cigarettes remained up to 5 years after a patient stopped smoking, but it later declined.
A study published in Neurology last month showed that people with multiple sclerosis who smoke have higher lesion volumes, more atrophy, and are at greater risk for blood–brain-barrier disruption (Neurology. 2009;73:504-510).
During a recent interview, lead author of that study, Robert Zivadinov, MD, from the University of New York School of Medicine and Biomedical Sciences in Buffalo, said: "Ours is the first study to demonstrate that smoking can promote brain-tissue injury in multiple sclerosis patients."
Autoimmune Disease and Smoking Don't Mix
The findings are similar to those of a study published in July (Arch Neurol. 2009;66:858-864). As previously reported by Medscape Neurology, investigators found that smoking contributes to rapid disease progression.
Asked for comment when the study was first published, Lily Jung, MD, from the Swedish Neuroscience Institute in Seattle, Washington, and member of the American Academy of Neurology, said that "this is just more ammunition for telling patients that to stop smoking is the easiest thing they can do to treat their multiple sclerosis."
During an interview, Dr. Hedström said she agrees. She also recommends that people with a family history of multiple sclerosis avoid smoking.
Neurology. 2009;73:696-701. Abstract
Wednesday, September 2, 2009
Use of Low-Dose Aspirin in Primary Prevention of Cardiovascular Events Not Recommended
From Heartwire
Fran Lowry
Medscape Conference Coverage, based on selected sessions at the:
European Society of Cardiology (ESC) Congress 2009
August 30, 2009 (Barcelona, Spain) — The use of low-dose aspirin in the primary prevention of cardiovascular events in healthy individuals with asymptomatic atherosclerosis is currently not warranted, according to the lead researcher of a large "real-world" study presented today at the European Society of Cardiology (ESC) 2009 Congress.
In the randomized trial of 3350 subjects deemed at high risk for cardiovascular and cerebrovascular events because of a low ankle-brachial index (ABI) (<0.95), aspirin had absolutely no effect on reducing events compared with placebo, Dr Gerry Fowkes (University of Edinburgh, Scotland) reported on behalf of the Aspirin for Asymptomatic Atherosclerosis (AAA) trialists.
However, aspirin did increase the risk of major hemorrhage.
The bleeding effect "is a real obstacle," Fowkes told heartwire . "I don't think the evidence is convincing enough as yet that aspirin should be used routinely in the general population."
The results of the trial are in conflict with findings from a meta-analysis from the Antithrombotic Trialists' (ATT) collaboration, which was published earlier this year in the Lancet [1], discussant Dr Carlo Patrono (Catholic University School of Medicine, Rome, Italy) told ESC attendees. He questioned how the results of AAA could be interpreted in light of the 12% relative risk reduction in serious cardiovascular events, largely driven by a reduction in nonfatal MI, that was seen in the ATT trial.
AAA Done Where the Need for Prevention Is Great
The AAA was a pragmatic trial, Fowkes explained, conducted in a deprived population in central Scotland, where rates of coronary heart disease and related mortality are high. "We wanted to get at where the problem actually existed in the population," he said.
Between 1998 and 2001, the AAA trialists invited men and women 50 to 75 years of age to undergo screening for asymptomatic atherosclerosis by measuring their ABI. A low ABI in otherwise-healthy individuals has been shown to be related to an increased risk of future cardiovascular events. Because it is simple and noninvasive, the ABI has the potential to be used as a screening test to detect high-risk individuals, Fowkes explained.
Of the more than 166 000 invitations that were sent out, the trialists ended up screening 28 980 individuals. Of this number, 3350 had a low ABI and were thus eligible to be entered into the trial.
They were randomly allocated to 100-mg enteric coated aspirin daily or to placebo and followed for a mean of 8.2 years. The primary end point of the trial was the composite of an initial fatal or nonfatal coronary event, stroke, or revascularization. Secondary end points were all vascular events, which included a composite of initial fatal or nonfatal coronary event, stroke, or revascularization, angina, intermittent claudication, transient ischemic attack, and all-cause mortality.
Patients in both groups were matched for age (mean age 62 years), gender (roughly 30% were men), and comorbidities. One-third of the study population consisted of smokers.
Aspirin had no effect in terms of reducing cardiovascular and cerebrovascular events. In all, there were 357 events, 181 (10.8%) in the aspirin group and 176 (10.5%) in the placebo group (hazard ratio 1.03, 95% CI 0.84–1.27).
Interestingly, cancer mortality was higher in the placebo group than in the aspirin group, Fowkes noted.
Adverse events, including major hemorrhage, were greater in the aspirin group (HR 1.71, 95% CI 0.99–2.97).
Fowkes pointed out that 40% of patients were noncompliant and did not take their aspirin as prescribed over the duration of the trial. Such a low compliance rate could have affected the results. "The 60% compliance rate is the typical level of compliance that you will find in the primary-prevention setting, and obviously there are many reasons that people stop taking aspirin. So whether aspirin is beneficial in clinical practice among patients who have a low ankle-brachial index and who are fully compliant with aspirin is unknown, and so our results cannot be extrapolated to that situation," he said.
heartwire asked Fowkes what he thinks may work for primary prevention in people with asymptomatic atherosclerosis, now that aspirin appears to be ineffective. "We don't have any strong evidence about what would work, but I think that given that these are high-risk individuals, it is probably reasonable to give them a statin. I think it would prove to be cost-effective to give a statin," he said. "Obviously, there is the possibility of giving a stronger antiplatelet such as clopidogrel or some of these new drugs that are being developed, but one would have to trial those properly."
AAA Underpowered
Patrono said the AAA study may have been underpowered and suggested that was one reason for its negative findings. "The sample size would have to be about four times larger to achieve the power to show a 12% relative risk reduction," he said.
Other reasons: "The presence of peripheral arterial disease, whether symptomatic or asymptomatic, may render platelet activation more critically dependent on ATP than thromboxane release, and there is some experimental as well as clinical evidence supporting this possibility."
An accelerated platelet turnover associated with peripheral arterial disease--at least in some patients--may also be a cause for the discrepancy, Patrono said.
To try to dissect out potential explanations, Fowkes and Dr Colin Baigent (Oxford University, UK), lead author of the ATT trial, have agreed to see how the AAA study would fit into the ATT meta-analysis. When available, the results will be posted by the Clinical Trial Service Unit, Patrono said.
Fowkes told heartwire that there is no reason to think that the relative reduction in cardiovascular events created by aspirin should be different in the primary or secondary setting. It's just that the benefits in the secondary setting far outweigh the risks. "The absolute reduction is much higher in secondary prevention than in primary prevention, but the level of bleeding is the same. So in secondary prevention, you've got a big reduction in events and a small amount of bleeding. In primary prevention, you have a smaller amount of reduction of events, and the same amount of bleeding. These two have got to be counterbalanced in the primary-prevention situation, and that is where the concern is at the moment."
Fran Lowry
Medscape Conference Coverage, based on selected sessions at the:
European Society of Cardiology (ESC) Congress 2009
August 30, 2009 (Barcelona, Spain) — The use of low-dose aspirin in the primary prevention of cardiovascular events in healthy individuals with asymptomatic atherosclerosis is currently not warranted, according to the lead researcher of a large "real-world" study presented today at the European Society of Cardiology (ESC) 2009 Congress.
In the randomized trial of 3350 subjects deemed at high risk for cardiovascular and cerebrovascular events because of a low ankle-brachial index (ABI) (<0.95), aspirin had absolutely no effect on reducing events compared with placebo, Dr Gerry Fowkes (University of Edinburgh, Scotland) reported on behalf of the Aspirin for Asymptomatic Atherosclerosis (AAA) trialists.
However, aspirin did increase the risk of major hemorrhage.
The bleeding effect "is a real obstacle," Fowkes told heartwire . "I don't think the evidence is convincing enough as yet that aspirin should be used routinely in the general population."
The results of the trial are in conflict with findings from a meta-analysis from the Antithrombotic Trialists' (ATT) collaboration, which was published earlier this year in the Lancet [1], discussant Dr Carlo Patrono (Catholic University School of Medicine, Rome, Italy) told ESC attendees. He questioned how the results of AAA could be interpreted in light of the 12% relative risk reduction in serious cardiovascular events, largely driven by a reduction in nonfatal MI, that was seen in the ATT trial.
AAA Done Where the Need for Prevention Is Great
The AAA was a pragmatic trial, Fowkes explained, conducted in a deprived population in central Scotland, where rates of coronary heart disease and related mortality are high. "We wanted to get at where the problem actually existed in the population," he said.
Between 1998 and 2001, the AAA trialists invited men and women 50 to 75 years of age to undergo screening for asymptomatic atherosclerosis by measuring their ABI. A low ABI in otherwise-healthy individuals has been shown to be related to an increased risk of future cardiovascular events. Because it is simple and noninvasive, the ABI has the potential to be used as a screening test to detect high-risk individuals, Fowkes explained.
Of the more than 166 000 invitations that were sent out, the trialists ended up screening 28 980 individuals. Of this number, 3350 had a low ABI and were thus eligible to be entered into the trial.
They were randomly allocated to 100-mg enteric coated aspirin daily or to placebo and followed for a mean of 8.2 years. The primary end point of the trial was the composite of an initial fatal or nonfatal coronary event, stroke, or revascularization. Secondary end points were all vascular events, which included a composite of initial fatal or nonfatal coronary event, stroke, or revascularization, angina, intermittent claudication, transient ischemic attack, and all-cause mortality.
Patients in both groups were matched for age (mean age 62 years), gender (roughly 30% were men), and comorbidities. One-third of the study population consisted of smokers.
Aspirin had no effect in terms of reducing cardiovascular and cerebrovascular events. In all, there were 357 events, 181 (10.8%) in the aspirin group and 176 (10.5%) in the placebo group (hazard ratio 1.03, 95% CI 0.84–1.27).
Interestingly, cancer mortality was higher in the placebo group than in the aspirin group, Fowkes noted.
Adverse events, including major hemorrhage, were greater in the aspirin group (HR 1.71, 95% CI 0.99–2.97).
Fowkes pointed out that 40% of patients were noncompliant and did not take their aspirin as prescribed over the duration of the trial. Such a low compliance rate could have affected the results. "The 60% compliance rate is the typical level of compliance that you will find in the primary-prevention setting, and obviously there are many reasons that people stop taking aspirin. So whether aspirin is beneficial in clinical practice among patients who have a low ankle-brachial index and who are fully compliant with aspirin is unknown, and so our results cannot be extrapolated to that situation," he said.
heartwire asked Fowkes what he thinks may work for primary prevention in people with asymptomatic atherosclerosis, now that aspirin appears to be ineffective. "We don't have any strong evidence about what would work, but I think that given that these are high-risk individuals, it is probably reasonable to give them a statin. I think it would prove to be cost-effective to give a statin," he said. "Obviously, there is the possibility of giving a stronger antiplatelet such as clopidogrel or some of these new drugs that are being developed, but one would have to trial those properly."
AAA Underpowered
Patrono said the AAA study may have been underpowered and suggested that was one reason for its negative findings. "The sample size would have to be about four times larger to achieve the power to show a 12% relative risk reduction," he said.
Other reasons: "The presence of peripheral arterial disease, whether symptomatic or asymptomatic, may render platelet activation more critically dependent on ATP than thromboxane release, and there is some experimental as well as clinical evidence supporting this possibility."
An accelerated platelet turnover associated with peripheral arterial disease--at least in some patients--may also be a cause for the discrepancy, Patrono said.
To try to dissect out potential explanations, Fowkes and Dr Colin Baigent (Oxford University, UK), lead author of the ATT trial, have agreed to see how the AAA study would fit into the ATT meta-analysis. When available, the results will be posted by the Clinical Trial Service Unit, Patrono said.
Fowkes told heartwire that there is no reason to think that the relative reduction in cardiovascular events created by aspirin should be different in the primary or secondary setting. It's just that the benefits in the secondary setting far outweigh the risks. "The absolute reduction is much higher in secondary prevention than in primary prevention, but the level of bleeding is the same. So in secondary prevention, you've got a big reduction in events and a small amount of bleeding. In primary prevention, you have a smaller amount of reduction of events, and the same amount of bleeding. These two have got to be counterbalanced in the primary-prevention situation, and that is where the concern is at the moment."
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