Exceptional parental longevity associated with lower risk of Alzheimer's disease and memory decline.

OBJECTIVES

To determine whether offspring of parents with exceptional longevity (OPEL) have a lower rate of dementia than offspring of parents with usual survival (OPUS).

DESIGN

Community-based prospective cohort study.

SETTING

Bronx, New York.

PARTICIPANTS

A volunteer sample of 424 community-residing older adults without dementia aged 75 to 85 recruited from Bronx County starting in 1980 and followed for up to 23 years.

MEASUREMENTS

Epidemiological, clinical, and neuropsychological assessments were completed every 12 to 18 months. OPEL were defined as having at least one parent who reached the age of at least 85. OPUS were those for whom neither parent reached the age of 85. Dementia was diagnosed according to case conference consensus based on Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised, criteria without access to information on parental longevity. Alzheimer's disease was diagnosed using established criteria.

RESULTS

Of 424 subjects, 149 (35%) were OPEL, and 275 (65%) were OPUS. Mean age at entry for both groups was 79. The OPEL group had a lower incidence of Alzheimer's disease (hazard ratio=0.57, 95% confidence interval=0.35-0.93). After adjusting for sex, education, race, hypertension, myocardial infarction, diabetes mellitus, and stroke, results were essentially unchanged. OPEL also had a significantly lower rate of memory decline on the Selective Reminding Test (SRT) than OPUS (P=.03).

CONCLUSION

OPEL develop dementia and Alzheimer's disease at a significantly lower rate than OPUS. Demographic and medical confounders do not explain this result. Factors associated with longevity may protect against dementia and Alzheimer's disease.