Purpose in Life May Reduce Alzheimer's Risk

From Medscape Medical News
Allison Gandey

March 3, 2010 — Elderly people with a strong sense of purpose in life are almost 2½ times less likely to develop Alzheimer's disease (AD), report researchers.

The new finding adds to emerging data suggesting that psychological and experiential factors are associated with cognitive impairment.

"Our results suggest that positive factors, such as having a sense of goal-directedness that guides behavior, may provide a buffer against negative health outcomes, particularly in old age," coauthor Lisa Barnes, PhD, from the Rush University Medical Center, Chicago, Illinois, told Medscape Psychiatry.

"These results are important because of the potential public health implications," she noted. "Purpose in life is something we can actually modify in old age by giving older adults specific strategies they can use to find meaning in activities, achieve purposes, and goals."

Investigators conducted a prospective, longitudinal, epidemiologic study of more than 900 community-dwelling, older people without dementia.

The group, led by Patricia Boyle, PhD, also at Rush University, evaluated purpose in life and a mean of 4 years of detailed annual follow-up clinical evaluations. Participants were from the Rush Memory and Aging Project.

Just more than 16% of the study population developed AD. In a proportional hazards model adjusted for age, sex, and education, investigators found that a greater purpose in life was associated with a substantially reduced risk for disease. The hazard ratio was 0.48, with a 95% confidence interval of 0.33 to 0.69 (P < .001).

In subsequent analyses, Dr. Boyle and her team examined the association of purpose in life with mild cognitive impairment, an early preclinical manifestation of AD.

They found that purpose in life also reduced the risk for incident cognitive impairment. The hazard ratio was 0.71, with a 95% confidence interval of 0.53 to 0.95 (P = .02).

"We cannot establish causality with certainty," Dr. Barnes said.
"However, we found that purpose in life was protective against Alzheimer's disease even after adjusting for important factors, such as depressive symptoms, neuroticism, social networks, and number of chronic medical conditions.
It also persisted in sensitivity analyses in which we sequentially excluded persons who developed Alzheimer's disease during each of the first 3 years of follow-up."

This, Dr. Barnes explains, was to address concerns that perhaps those in the cohort had undiagnosed or mild AD.

"Although our ability to infer causation may be limited, these kinds of additional controls strengthen our confidence in the findings," she noted.

Psychological Well-Being

Another recent study found that a sense of purpose in life was the most important factor in determining mental health outcomes after serious trauma (Am J Psychiatry. 2008;165:1566-1575).

"We found that the most important psychosocial factor associated with resilience or recovered status was a sense of higher purpose in life," Adriana Feder, MD, from the Mount Sinai School of Medicine, New York City, told Medscape Psychiatry when the study was first published online in November.
"We also found that mastery, or having a strong sense of control over one's life, was significantly associated with recovered status."

This new study is reportedly the first to evaluate purpose in life and the risk for AD, but the investigators have evaluated other health outcomes in this same cohort and observed a reduced risk for death.

"Purpose in life is an indicator of human thriving that has been hypothesized to be related to better psychological well-being," Dr. Barnes said.

This study was funded by the National Institute on Aging, the Illinois Department of Public Health, and the Robert C Borwell Endowment Fund. The researchers have disclosed no relevant financial relationships.

Arch Gen Psychiatry. 2010;67:304-310.