A POPULATION STUDY OF APOE GENOTYPE AT THE AGE OF 85 - RELATION TO DEMENTIA, CEREBROVASCULAR-DISEASE, AND MORTALITY

Objectives-To study the association on apoE genotypes with dementia an d cerebrovascular disorders in a population based sample of 85 year ol d people. Methods-A representative sample of 85 year old people (303 n on-demented, 109 demented) were given a neuropsychiatric and a medical examination and head CT. The apoE isoforms were determined. Dementia was diagnosed according to DSM-III-R. Results-At the age of 85, carrie rs of the apoE epsilon 4 allele had an increased odds ratio (OR) for d ementia (1.9; p<0.01) and its subtypes Alzheimer's disease (1.9; p<0.0 5) and vascular dementia (2.0; p<0.05). Among those categorised as hav ing vascular dementia, the apoE epsilon 4 allele was associated with m ixed Alzheimer's disease-multi-infarct dementia (OR 6.5; p<0.05), but not with pure multi-infarct dementia (OR 1.5; NS). Only carriers of th e apoE epsilon 4 allele who also had ischaemic white matter lesions on CT of the head had an increased OR for dementia (OR 6.1; p=0.00003), and its main subtypes Alzheimer's disease (OR 6.8; p=0.002) and vascul ar dementia (OR 5.6; p=0.0007), whereas carriers of the apoE epsilon 4 allele without white matter lesions had an OR for dementia of 1.0 (OR for Alzheimer's disease 1.8; NS and for vascular dementia 0.6; NS) an d non-carriers of the apoE epsilon 4 allele with white matter lesions had an OR for dementia of 2.2; NS (OR for Alzheimer's disease 2.7; NS and for vascular dementia 1.6; NS). The apoE allele variants were not related to mortality or incidence of dementia between the ages of 85 a nd 88. The epsilon 2 allele was related to a higher prevalence of stro ke or transient ischaemic attack at the age of 85 (OR 2.1; p<0.05) and a higher incidence of multiinfarct dementia during the follow up (OR 2.9; p<0.05). Conclusions-Neither the apoE epsilon 4 allele nor white matter lesions are sufficient risk factors by themselves for dementia at very old ages, whereas possession of both these entities increases the risk for Alzheimer's disease and vascular dementia substantially.