Risk factors for earlier dementia onset in autopsy-confirmed Alzheimer's disease, mixed Alzheimer's with Lewy bodies, and pure Lewy body disease.

INTRODUCTION

Clinical Alzheimer's disease (AD) and dementia with Lewy bodies often have mixed AD and Lewy pathology, making it difficult to delineate risk factors.

METHODS

Six risk factors for earlier dementia onset due to autopsy-confirmed AD (n = 647), mixed AD and Lewy body disease (AD + LBD; n = 221), and LBD (n = 63) were entered into multiple linear regressions using data from the National Alzheimer's Coordinating Center.

RESULTS

In AD and AD + LBD, male sex and apolipoprotein E (APOE) ɛ4 alleles each predicted a 2- to 3-year-earlier onset and depression predicted a 3-year-earlier onset. In LBD, higher education predicted earlier onset and depression predicted a 5.5-year-earlier onset.

DISCUSSION

Male sex and APOE ɛ4 alleles increase risk for earlier dementia onset in AD but not LBD. Depression increases risk for earlier dementia onset in AD, LBD, and AD + LBD, but evaluating the course, treatment, and severity is needed in future studies.