PTSD may double risk of dementia

A study supported by the NIHR UCLH Biomedical Research Centre carried out at UCL has found that people who have experienced post-traumatic stress disorder (PTSD) are up to twice as likely to develop dementia later in life.

The research, published in the British Journal of Psychiatry, is the first meta-analysis of global evidence on PTSD and dementia risk.

For the study, the researchers analysed findings from 13 studies conducted on four continents, including data from a total of 1,693,678 people, investigating whether a PTSD diagnosis was associated with 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. Analysing data from two studies that used different methods, they found that PTSD was associated with double the odds of developing dementia.

Senior author Dr Vasiliki Orgeta (UCL Psychiatry) said: “Our 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.

“A lot of people with PTSD don’t access treatment, sometimes due to a lack of mental health care capacity but also because of stigma which often keeps people away from seeking help. We now have more evidence of how traumatic experiences and accessing treatment could have a long-lasting impact for individuals and influence future risk of developing 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 trauma, contributing to threat and stress-related activity in the brain, while withdrawal from social life may reduce cognitive reserve and resilience.

In addition to support from the BRC at UCLH, the researchers were supported by the Alzheimer’s Society.