Background: The є4-allele of Apolipoprotein-E (APOE) and head injury are risk factors for dementia diseases, and these factors may act synergistically to further increase the risk. The aim of the present study was to examine the association between mild head injury, APOE, and dementia.
Methods: Data were obtained from the Betula prospective population-based study of aging, memory, and health. The study included 543 participants in the age range 40-85 years, free of dementia at baseline, who were followed-up within a 5-year interval. Dementia was classified using the Diagnostic and Statistical Manual of Mental Disorders Criteria. Information of previous head injury was done through screening of the participants’ answers to health questionnaires both at baseline and at following test occasions.
Results: We found that subjects with head injury but without APOE є4 had no increased risk of dementia. Subjects with APOE є4 had elevated risk and those with both APOE є4 and head injury had the highest risk (OR = 5.2).
Conclusions: This study confirms that APOE ε4 constitutes a risk factor of dementia, that mild injury in isolation does not increase the risk, but that head injury in combination with the APOE ε4 lead to increased risk of dementia.
2007. Vol. 19