In a new study, researchers found people who have experienced post-traumatic stress disorder (PTSD) are up to twice as likely to develop dementia later in life.
This is the first review of global evidence on PTSD and dementia risk.
The research was conducted by UCL scientists.
In the study, the researchers analyzed findings from 13 studies conducted on four continents, including data from a total of 1,693,678 people, examining whether a PTSD diagnosis was associated with an increased risk of dementia up to 17 years later.
By pooling data from eight of the studies, the researchers found that people with PTSD faced a 61% higher risk of dementia.
Analyzing data from two studies that used different methods, they found that PTSD was associated with double the odds of developing dementia.
Dementia risk among people who have had PTSD was higher in the general population compared to veterans, as in the general population people with a PTSD diagnosis was more than twice as likely to develop dementia.
The researchers say this may point to an effect of treating PTSD: veterans are typically more likely to receive treatment for PTSD (at least in the countries the studies were conducted), so the findings suggest that treating PTSD may reduce subsequent dementia risk.
The study provides important new evidence of how traumatic experiences can impact brain health, and how the long-term effects of trauma may impact the brain in many ways increasing vulnerability to cognitive decline and dementia.
The researchers say the risk could be higher than the studies suggest, as PTSD also increases the likelihood of developing other known dementia risk factors, such as depression, social isolation, or elevated alcohol intake.
Most of the studies adjusted for some of these factors, so the overall findings might underestimate the true cost of PTSD.
It remains unclear how PTSD raises dementia risk, but the researchers say it may be related to hypervigilance and recurrent re-experiencing of the trauma, contributing to threat and stress-related activity in the brain, while withdrawal from social life may reduce cognitive reserve and resilience.
This research is the latest in a series of UCL-led studies testing how factors across the lifespan can affect dementia risk, including a major review of 12 risk factors such as lack of education, hearing loss, and smoking, as well as other recent studies on how repetitive negative thinking and living alone can increase dementia risk.
One author of the study is Dr. Vasiliki Orgeta (UCL Psychiatry).
The study is published in the British Journal of Psychiatry.
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