OBJECTIVES: We sought to identify demographic and clinical features that were associated with expression of symptoms in the presence of Alzheimer disease (AD) neuropathologic changes. METHODS: We studied 82 asymptomatic (Clinical Dementia Rating global score = 0) and 824 symptomatic subjects (Clinical Dementia Rating score >0) with low to high AD neuropathologic changes at autopsy who were assessed at 1 of 34 National Institute on Aging-funded Alzheimer's Disease Centers. All subjects underwent a clinical examination within 1 year of death. Logistic regression was used to evaluate factors associated with the odds of being asymptomatic vs symptomatic. RESULTS: Asymptomatic subjects tended to have low neurofibrillary tangle scores but a wide range of neuritic plaque frequencies. There were, however, a few asymptomatic subjects with very high tangle and neuritic plaque burden, as well as symptomatic subjects with few changes. In the multivariable model, asymptomatic subjects were older (odds ratio [OR] = 1.04; 95% confidence interval [CI] = 1.01-1.07), had lower clinical Hachinski Ischemic Score (OR = 0.82; 95% CI = 0.69-0.97), were less likely to have an APOE ε4 allele (OR = 0.36; 95% CI = 0.16-0.83), and had lower neurofibrillary tangle score (OR = 0.28; 95% CI = 0.17-0.45) compared with symptomatic subjects. CONCLUSIONS: Dissociating clinical symptoms from pathologic findings better allows for investigation of preclinical AD. Our results suggest that although the severity of the pathology, particularly neurofibrillary tangles, has a large role in determining the extent of symptoms, other factors, including age, APOE status, and comorbidities such as cerebrovascular disease also explain differences in clinical presentation.
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