PTSD may double risk of dementia

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.*

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 were 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.

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.

The study’s first author, Mia Maria Günak, led the research as part of her MSc dissertation in Dr Orgeta’s lab at UCL. She commented: “Our findings add to a growing body of evidence that dementia can sometimes be prevented by addressing risk factors throughout an individual’s life course.

“Here we have identified an additional group of people who face an elevated risk of dementia, who may benefit from further mental health support.”

Dr Orgeta added: “PTSD, which appears to be common among people who have been hospitalised with Covid-19, remains an underdiagnosed, undertreated, and under researched mental health condition, yet it can have serious long-term consequences. As our study has shown, PTSD impacts our brain health by increasing vulnerability to dementia. An important question is how, and whether we could learn from these findings to develop preventative treatments for those with elevated risk.”  

The researchers were supported by the NIHR University College London Hospitals Biomedical Research Centre and the Alzheimer’s Society

Fiona Carragher, Director of Research and Influencing at Alzheimer’s Society said: “Although reasons for this aren’t fully clear, this comprehensive research, part-funded by Alzheimer’s Society, draws together a growing body of evidence linking PTSD with an increased dementia risk. It provides a strong case for further studies to understand whether treating PTSD could have the added benefit of reducing the risk of developing dementia later in life.

“With UK dementia cases set to skyrocket to 1 million by 2025, growing evidence around risk factors provides hope that we can reduce our risk of dementia – we already know that a healthy lifestyle is good for both our body and mind. Unfortunately, due to the ongoing pandemic, vital medical research like this has suffered a devastating financial blow and desperately needs Government investment to ensure this life changing work and the hope it provides to everyone affected by dementia is not lost.”

This research is the latest in a series of UCL-led studies investigating how modifiable factors across the lifespan can affect dementia risk, including a major review and meta-analysis 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.**

Links

• Research paper in The British Journal of Psychiatry
• Dr Vasiliki Orgeta’s academic profile
• UCL Psychiatry
• UCL Faculty of Brain Sciences
• * Eight studies used hazard ratios to estimate the impact of PTSD on dementia risk, while two others used odds ratios, so they were pooled separately. Three other studies were included in the meta-analyses but were not part of the pooled data
• ** Four in 10 dementia cases could be prevented or delayed (July 2020), Repetitive negative thinking linked to dementia risk (June 2020), Living alone linked with higher dementia risk (July 2020)
• Media coverage

Image

• Talking therapies can help some people with PTSD. Source: cottonbro on Pexels

Media contact

Chris Lane

Tel: +44 (0)20 7679 9222

Email: chris.lane [at] ucl.ac.uk