The study, by researchers at the Sahlgrenska Academy at Gothenburg University, has been published in the medical journal Brain and is the first Swedish study to have followed women under 35 which shows a link between stress and dementia.
“Stress was defined as a feeling of irritation, tension, nervousness, anxiety, fear or sleeping difficulties for a month or longer in relation to employment, health, family situation or some other reason,” said Lena Johansson, a researcher at Department of Neuropsychiatric Epidemiology (Epinep), Section of Psychiatry and Neurochemistry at the Sahlgrenska Academy.
The study involved a sample of women who were first studied in 1968, when they were 38-60-years-old and then again in 1974, 1980, 1992 and 2000.
A question pertaining to psychological stress was included in the 1968, 1974 and 1980 studies and was answered by 1,415 people.
Over the 35 years of the study 161 of the participants developed dementia, normally Alzheimer’s. The risk for developing dementia has been calculated as 65 percent higher among women who reported periods of stress when middle-aged in comparison to those who reporting being stress-free.
For the participants who reported experiencing stress symptoms at every one of the study surveys, the risk was doubled.
“This study is the first to show that stress in middle-age can result in dementia in old age, and confirms similar findings from animal studies. Stress has been previously shown to increase the risk of diseases such as stroke, myocardial infarction and hypertension,” said Johansson.
Lena Johansson argues that the study could help shed light on the risk factors for dementia and called for further research into the illness.
“Most of those who said they were stressed did not develop dementia. It is currently therefore not possible to advise on reducing stress or to warn of the danger of high levels of stress due to the higher risk of dementia,” she said.