Familial aggregation of dementia with Lewy bodies.

BACKGROUND Familial aggregation of dementia with Lewy bodies (DLB) remains unclear. OBJECTIVES To determine the degree of family aggregation of DLB by comparing DLB risk between siblings of probands with clinically diagnosed DLB and siblings of probands with clinically diagnosed Alzheimer disease in a cohort of Caribbean Hispanic families and to explore the degree of aggregation of specific clinical manifestations (ie, cognitive fluctuations, visual hallucinations, and parkinsonism) in DLB. DESIGN Familial cohort study. SETTING Academic research. PATIENTS We separately compared risks of possible DLB, probable DLB, and clinical core features of DLB (cognitive fluctuations, visual hallucinations, and parkinsonism) between siblings of probands with clinically diagnosed DLB (n = 344) and siblings of probands with clinically diagnosed Alzheimer disease (n = 280) in 214 Caribbean Hispanic families with extended neurologic and neuropsychological assessment. MAIN OUTCOME MEASURES We applied general estimating equations to adjust for clustering within families. In these models, age and proband disease status were independent variables, and disease status of siblings was the measure of disease risk and the dependent variable. RESULTS Compared with siblings of probands having clinically diagnosed Alzheimer disease, siblings of probands having clinically diagnosed DLB had higher risks of probable DLB (odds ratio [OR], 2.29; 95% confidence interval [CI], 1.04-5.04) and visual hallucinations (2.32; 1.16-4.64). They also had increased risks of possible DLB (OR, 1.51; 95% CI, 0.97-2.34) and cognitive fluctuations (1.55; 0.95-2.53). CONCLUSIONS Dementia with Lewy bodies and core features of DLB aggregate in families. Compared with siblings of probands having clinically diagnosed AD, siblings of probands having clinically diagnosed DLB are at increased risks of DLB and visual hallucinations. These findings are an important step in elucidating the genetic risk factors underlying DLB and in delineating DLB from other neurodegenerative diseases, such as Alzheimer disease.