Am J Psychiatry 1995; 152:424-430
Copyright © 1995 by American Psychiatric Association
Age at onset and familial risk in Alzheimer's disease
G Li, JM Silverman, CJ Smith, ML Zaccario, J Schmeidler, RC Mohs and KL Davis
Psychiatry Service, Bronx VA Medical Center, NY 10468.
OBJECTIVE: The authors investigated the relationship between probands' age
at onset of Alzheimer's disease with the risk of primary progressive
dementia in the probands' first-degree relatives. METHOD: Two hundred
probands with clinically diagnosed Alzheimer's disease and 179 nondemented
elderly probands were recruited from the Mount Sinai Alzheimer's Disease
Research Center, located at Mount Sinai Hospital and the Bronx Veterans
Affairs Medical Center. Demographic and diagnostic data were collected on
1,398 of the first-degree relatives of the probands with Alzheimer's
disease and 955 first-degree relatives of the nondemented probands.
RESULTS: Cox proportional hazards regression analysis showed a significant
inverse relationship between age at onset of Alzheimer's disease in
probands and greater familial risk in their relatives. Follow-up analyses
indicated that the most commonly used age at onset cutoff point--65
years--was one of the points where an association with familial aggregation
is least likely to be revealed; other onset cutoff ages (e.g., 55, 70, and
75) better identified Alzheimer's disease groups with differing
familial/genetic risks. CONCLUSIONS: The authors conclude that patients
with an earlier age at onset of Alzheimer's disease are more likely to have
relatives with Alzheimer's disease than are patients with a later age at
onset of the disease. An onset age of 70 best differentiated probands whose
relatives were at higher risk from those whose relatives were at lower
risk.
