Season of birth for Alzheimer's disease in the Southern Hemisphere.

Season of birth was compared in 170 clinically diagnosed cases of Alzheimer's disease (AD) in Australia and 170 matched controls. A further comparison was made with a large population sample of the elderly. No evidence for seasonality of birth was found. This finding held not only for the total series of 170 cases, but also for the 143 born in the Southern Hemisphere, for sporadic cases, and for those with earlier onset. These negative findings in Australia contrast with the positive finding in London by Philpot et al. (1989).