While the number of people worldwide with dementia is increasing dramatically as a result of longevity advancements, the pathogeneses of these diseases are not sufficiently understood. Lena Johansson , from Sahlgrenska Academy at Gothenburg University (Sweden) followed a group of 1462 women, ages 38 to 60 years at the study’s start, for a 35-year period, seeking to analyze the relationship between psychological stress in midlife and the development of dementia in late-life.   During the 35 years of the study, 161 of the participants developed dementia, mainly in the form of Alzheimer's disease. The risk of dementia was about 65% higher in women who reported repeated periods of stress in middle age than in those who did not. In women who reported stress throughout the study period, the risk more than doubled. Noting that this is the first study to show that stress in middle age can lead to dementia in old age, and confirms similar findings from studies of animals, the team concludes that: “We found an association between psychological stress in middle-aged women and development of dementia, especially Alzheimer’s disease.”