Head trauma and the risk of Alzheimer's disease.

A population-based case-control study of the association between head trauma and Alzheimer's disease was conducted in the Netherlands from 1980 to 1987. The study comprised 198 patients with clinically diagnosed early onset Alzheimer's disease and 198 age- and sex-matched population controls. Adjusted for sex, age, family history of dementia, and education, the odds ratio of a history of head trauma with loss of consciousness was 1.6 (95% confidence interval (CI) 0.8-3.4). The odds ratio for men was 2.5 (95% CI 0.9-7.0), and that for women was 0.9 (95% CI 0.3-2.8). The increase in odds ratio was limited to head trauma that occurred within the period of 10 years prior to the onset of dementia (odds ratio = 10.0; 95% CI 1.0-96.8). There was no evidence of effect modification by family history of dementia as measured on a multiplicative scale. However, the power to show interaction may have been low in this study. The authors' findings are compatible with the view that head trauma may be implicated in Alzheimer's disease, with a short lag time between the head trauma and the first symptoms of disease. The association needs to be confirmed in a prospective follow-up study to fully exclude the possibility of recall bias.

Is parental age related to the risk of Alzheimer's disease?

Advanced maternal and paternal age were investigated as putative risk factors for AD in 198 clinically diagnosed Alzheimer patients and in 198 randomly selected healthy controls. No significant differences in average age of fathers and of mothers at birth of the subject were observed. The risk of AD was not significantly different across categories of maternal and paternal age. The association with parental age was not different for sporadic and familial AD. These findings do not support the view of a maternal or paternal age effect on AD.

History of dementia and Parkinson's disease in 1st-degree relatives of patients with Alzheimer's disease.

We assessed the family history of dementia and Parkinson's disease in 198 Dutch patients with Alzheimer's disease diagnosed before the age of 70 years, and in 198 age- and sex-matched healthy population controls. Of the Alzheimer patients, 48% had at least 1 1st-degree relative with dementia, compared with 19% of the controls. There were 24 patients and 1 control with 2 or more 1st-degree relatives with dementia, yielding a relative risk of 40.0. More Alzheimer patients than controls had a 1st-degree relative with Parkinson's disease, with a relative risk of 2.9. This study strongly confirms earlier findings of familial aggregation of Alzheimer's disease and provides evidence for familial aggregation of Alzheimer's disease with Parkinson's disease. The latter may point at a joint etiology of these diseases.