Long-term relationships ward off Alzheimer's - study
Herald Sun (Aust) July 04, 2009
BEING in a long-term relationship protects you against Alzheimer's disease in later life, researchers say. People with a partner in middle age have half the risk of developing dementia of those who live alone. Getting divorced and becoming widowed in mid-life raises the risk threefold. The study, by Swedish researchers, is one of the first to focus on marital status and the risk of dementia.

Researchers interviewed 2000 people aged about 50 in the 1970s and '80s. About 1400 were re-examined in 1998, when their ages ranged from 65 to 79.
http://www.news.com.au/heraldsun/story/0,21985,25730106-662,00.html