APOE Genotype, Family History of Dementia, and Alzheimer Disease Risk: A 6-Year Follow-up Study | Dementia and Cognitive Impairment | JAMA Neurology | JAMA Network
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Original Contribution
December 2004

APOE Genotype, Family History of Dementia, and Alzheimer Disease Risk: A 6-Year Follow-up Study

Author Affiliations

Authors Affiliations: Aging Research Center, Division of Geriatric Epidemiology and Medicine, Department of Neurotec, Karolinska Institutet and Stockholm Gerontology Research Center, Stockholm, Sweden.

Arch Neurol. 2004;61(12):1930-1934. doi:10.1001/archneur.61.12.1930

Background  Both family aggregation and apolipoprotein E (APOE) ε4 allele are well-known risk factors for dementia, but the relation between these two factors remains unclear.

Objective  To explore whether the risk of dementia and Alzheimer disease (AD) due to a positive family history is explained by APOE genotypes.

Design  Community-based cohort study.

Setting  The Kungsholmen district of Stockholm, Sweden.

Participants  A total of 907 nondemented people 75 years or older, followed up for 6 years to detect incident dementia and AD cases according to the diagnostic criteria of the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition.

Main Outcome Measures  Risk of dementia and AD by Cox proportional hazards models after controlling for several potential confounders.

Results  Subjects who had at least 2 siblings with dementia were at an increased risk of AD. Individuals with both APOE ε4 allele and at least 2 affected first-degree relatives had a higher risk of dementia and AD compared with those without these 2 factors. Similar results were obtained for history of dementia separately in parents or siblings. Among the ε4 allele carriers, subjects with 2 or more first-degree demented relatives had increased risk of dementia and AD, whereas no increased risk was detected among non–ε4 carriers.

Conclusions  Family history of dementia was associated with an increased risk of dementia and AD in this very old population, but only among APOE ε4 carriers. This suggests the existence of other genetic or environmental risk factors that may be active in the presence of the APOE ε4 allele.