Post-traumatic stress disorder linked to increased risk of dementia – new research

This link was found in veterans, war refugees, and those with non-combat traumatic experiences.

Dementia is one of the greatest global health challenges. As the world’s population continues to age and to live longer, the number of people affected by dementia is expected to rise to 130 million by 2050. Given that there is no cure for dementia, there’s an urgent need to identify modifiable risk factors to prevent or delay the onset of dementia.

We’ve recently identified post-traumatic stress disorder (PTSD) as a potential risk factor for developing dementia. PTSD is caused by traumatic experiences such as childhood trauma, war or being the victim of violence or abuse. People with PTSD experience distressing symptoms, often for many years. These symptoms can include flashbacks of the traumatic event, avoiding reminders of the event, hyper-arousal, and memory deficits related to traumatic experiences.

Our study is the first to try and quantify the risk of developing dementia associated with PTSD. We searched through nearly 8,000 papers to identify all existing studies worldwide, across different populations, that examined the relationship between PTSD and future risk of dementia. We only included studies that were conducted over a long period of time to ensure that PTSD was present before the onset of dementia.

We found 13 studies that specifically investigated the link between dementia and PTSD. Studies were conducted on four continents and included data from 1,693,678 people. Apart from one, all studies found that compared with those without the condition, PTSD was associated with an increased risk of developing dementia, based on subsequent follow-ups from one up to 17 years later.

A link between PTSD diagnosis and dementia was found not only in veterans and war-refugees, but also in those with non-combat related traumatic experiences. The link remained even after other factors that could have been influencing the relationship between PTSD and dementia were taken into account. These included a person’s gender, age, physical health (including whether they had certain health conditions, such as blood vessel disease, which is known to increase dementia risk, and other psychiatric conditions, such as depression and alcohol misuse.

We performed two meta-analyses, a technique that statistically combines results from each study to estimate the overall risk. It revealed that the rate of being diagnosed with dementia in people with PTSD was 1.61 to almost two times the rate in those without PTSD.

However, our review did not investigate the underlying reasons for the association between dementia and PTSD, so these remain unclear. One possibility is that PTSD speeds up cognitive decline in older age. For example, the stress experienced by PTSD symptoms, which may be continuous over many years, may wear down the brain, making it more vulnerable to cognitive decline and dementia. PTSD is also often present with other known risk factors that increase the likelihood of developing dementia, such as depression, social isolation, or higher alcohol intake.

Treatment may be important for reducing risk.Treatment may be important for reducing risk.

Our study allows us to conclude for the first time that PTSD is a strong and potentially modifiable risk factor for dementia. This research is important as we have been able to identify specific groups of people who are more vulnerable to developing dementia.

Many people with PTSD do not access treatment. This is sometimes due to a lack of mental healthcare services, or because of perceived stigma associated with having a mental health condition. We now have more evidence showing how traumatic experiences – and accessing treatment to deal with them – could have a long-lasting effect on people. Treatment may also influence future risk of developing dementia. However, we don’t yet know whether treating PTSD may reduce the dementia risk, or delay its onset.

As our study has shown, PTSD affects 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 greater risk.

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By Vasiliki Orgeta / Associate Professor of Psychology of Ageing and dementia, UCL

Dr Vasiliki Orgeta is an Associate Professor at the Division of Psychiatry, Faculty of Brain Sciences, at University College London and a Senior Fellow of the Alzheimer's Society. Vasiliki completed a BSc (Hons) in Psychology (First Class) at the University of Aberdeen in 2002, and her PhD also at the Department of Psychology at University of Aberdeen in 2007, investigating emotion-cognition interactions in late life (awarded without corrections). She joined UCL in 2008, and since then has been involved in systematic reviews of psychological treatments for people with dementia (with the Cochrane Review Group), and in RCTs developing and evaluating psychosocial interventions for people with dementia (IDEA, REMCARE and iCST trials). She has developed a psychological intervention for preventing depressive symptoms in people with early-stage dementia, work funded by the Alzheimer's Society, http://www.ucl.ac.uk/psychiatry/idea.

Dr Vasiliki Orgeta is a research psychologist interested in emotional well-being in people with dementia and their family carers and how stress could be influencing risk of developing dementia. Her research focuses on systematic reviews and meta-analyses of psychological and psychosocial interventions in dementia and mild cognitive impairment, and in the development and evaluation of these interventions using randomised controlled trials (RCTs).

(Source: theconversation.com; September 17, 2020; https://tinyurl.com/y5gnc2om)
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