Stress Disorders Increase Risk of Dementia
Previous research has shown an association between post-traumatic stress disorder (PTSD) and dementia, but few studies have examined associations between dementia and other stress disorders, or looked at these associations by sex.
Now, a new study led by a School of Public Health researcher finds that even stress disorders that are not considered severe or chronic may increase risk of dementia, particularly among men.
The study, published in the American Journal of Epidemiology, found that a stress disorder diagnosis was associated with as much as a nearly three-fold increase in the rate of developing dementia. The association between most stress disorder diagnoses and dementia was more pronounced among men, except for PTSD, which had a stronger association for women.
“People who are experiencing stress-related mental health symptoms, but who do not meet diagnostic criteria for PTSD or one of the other stress disorders that are thought to be more severe, have similarly elevated rates of dementia,” says study lead author Jaimie Gradus, associate professor of epidemiology. “This suggests that people with some stress-related mental health symptoms should also be the focus of intervention and prevention efforts, even if they do not meet diagnostic criteria for a stress disorder.”
Gradus and her colleagues used data from several of Denmark’s nationwide registries of social and medical information to create a cohort of 47,047 Danish residents over 40 years old who received stress disorder diagnoses between 1995 and 2011 and did not have dementia in 1995. They categorized diagnoses as PTSD, acute stress reaction (similar to PTSD but lasting no more than about a month), adjustment disorder (difficulty coping with or adjusting to a source of stress), other stress reactions, and unspecified stress reactions.
The researchers also created a comparison cohort: for each member of the first cohort, this second cohort included five Danish residents of the same age and sex, but without a stress disorder diagnosis for the period and without dementia in 1995. They then compared the two cohorts as members were diagnosed with dementia, emigrated or died, or until the end of 2011.
They found that people with acute stress reaction had 1.6 times the rate of dementia than comparison cohort members, those with PTSD had 2.0 times the rate of dementia, those with adjustment disorder had 2.4 times the rate of dementia, those with other stress reactions had 2.8 times the rate of dementia, and those with unspecified stress disorders had 2.2 times the rate of dementia.
Men with stress disorder diagnoses were more likely to develop dementia than women with the same diagnoses, with the exception of PTSD. Among those diagnosed with PTSD, women were more likely to develop dementia than men.
The researchers also analyzed the data to see if the results could be explained by an event or illness/injury causing both a stress disorder and dementia. However, they found that the amount of time between a stress disorder diagnosis and a dementia diagnosis varied widely among members of the cohort, suggesting that this was not the case.
Although there are many hypotheses about what might tie stress disorders and dementia together, more research is needed to understand the mechanisms of the association, the authors wrote.