Risk Factors in Alzheimer’s Disease

Abstract

The role of specific risk factors for Alzheimer’s disease (AD) is undefined. We compared medical histories in 259 patients with clinically diagnosed AD with those in cognitively intact patients (CI;n=36). The two groups were comparable in age (mean±SEM 73.3±0.6 in AD, 70.9 ±2.1 in CI), race (>95% white), and socioeconomic status, although they differed in male:female ratio (1:2 in AD; 1.6:1 in CI). Stroke was more common in CI (11.1% vs 1.5%, p=.006), presumably because demented patients with stroke tend to be diagnosed as multi-infarct dementia rather than AD. Family history for dementia was positive in 35.9% of AD patients, but only 5.6% of CI patients (p<0.001). Family history of other genetic disorders was more often positive in AD than in CI, but these differences were not statistically significant (thyroid disease in 1.5% vs 0%; Down’s in 0.8% vs 0%, and congenital malformations in 1.2% vs 0%). Other factors previously implicated in AD were not significantly more common in AD than in CI (head trauma in 4.2% vs 8.3%; peptic ulcers (presumably with aluminum-containing antacid use) in 5.8% vs 8.3%, alcoholism in 0.7% vs 0%, job-related toxic exposures in 1.5% vs 0%, and thyroid disease in 2.3% vs 0%). There were also no significant differences in prevalence of cancer; lung, biliary, or gastrointestinal disease; or arthritis. These data suggest that genetic factors are more important than environmental ones in the pathogenesis of AD, although case-control studies of large numbers of subjects are needed to determine if small differences in exposure to environmental factors are statistically significant.