Severe head injury hastens age of onset of Alzheimer's disease.

Head trauma has been found with greater frequency in the histories of Alzheimer patients than age-matched controls in some studies, but not in others. We hypothesized that events that accelerate neuron loss, such as significant head trauma, hasten the onset of symptoms of Alzheimer's disease in persons vulnerable to the disorder. Retrospective data on 148 probable Alzheimer patients and 33 demented controls were examined. Alzheimer patients with severe head injury before the age of 65 showed onset of symptoms at an earlier age than Alzheimer patients without head trauma.