Researchers led by Dr Lena Johansson conducted the study on a group of 800 Swedish women who first underwent neuropsychiatric tests in 1968 with follow up tests conducted in 1974, 1980, 1992, 2000 and 2005. All of the women were born between 1914 and 1930 and after the initial test, they were asked whether they had suffered from the impact of 18 different types of dramatic events, known as psychosocial stressors, such as divorce, work related problems, problems with children etc.
The researchers found that over a quarter of the women reported to have suffered from at least one stressful event while around 23 percent suffered from two events, 20 percent three and 16 percent four or more events.
Around 153 women, or 19 percent, developed dementia during the study period with 104 of the women being diagnosed with Alzheimer's disease later on. The researchers found that the number of stressors reported in 1968 was linked with a 21 percent increased risk of Alzheimer's disease and 15 percent increased risk of dementia.
"Common stressors may have severe and long-standing physiological and psychological consequences. The number of psychosocial stressors measured in middle-aged women was related to distress and incidence of Alzheimer's disease almost four decades later", the researchers wrote in their report.