Sex differences in genetic risk for dementia.

We used two Swedish twin samples to test whether women are at greater risk than men of developing dementia and whether there are sex differences in mechanisms underlying dementia and cognitive dysfunction. Dementia analyses found no sex differences in incidence of dementia or Alzheimer's disease among initially intact participants followed longitudinally. Twin analyses indicated a substantial genetic influence on liability to incident dementia. Although sex differences in model parameters were not statistically significant, for women but not men an equally attractive model included genetic influence due to both additive effects and dominance or epistasis. In the cognitive dysfunction analyses, results from a sex limitation model raise the possibility that either different genes or different environments have a role for men and women. We conclude that women are not at higher risk of developing dementia, but there is a hint that different genetic processes may be involved for women than for men.