Metastudy finds PTSD can double the risk of dementia

Researchers from University College London have conducted the world’s first meta-analysis of the relationship between post-traumatic stress disorder (PTSD) and dementia. Encompassing over a million subjects the study found PTSD, especially if left untreated, can double a person’s risk of developing dementia in their senior years.

The new study, published in the British Journal of Psychiatry, describes dementia as perhaps the biggest global health challenge of the 21st century. More than 50 million people worldwide currently suffer from the condition, and estimates suggest the global prevalence of dementia will triple by 2050. In the absence of effective treatments, the short-term key to managing this degenerative condition will be identifying, and managing early, the biggest risk factors that can influence dementia development.

A recent systemic review from a team of Canadian researchers found evidence of a bi-directional relationship between PTSD and dementia. Investigating 25 prior studies, the review concluded PTSD does increase the risk of dementia, but dementia also increases the risk of delayed-onset PTSD.

This new meta-analysis set out to try to quantify the association between PTSD and increased dementia risk. Data from 13 studies were pooled, encompassing 1.69 million subjects. Overall, the research found a PTSD diagnosis was linked with a 61 percent greater likelihood of developing dementia.

Interestingly, the rate of dementia in veterans with PTSD was lower than that seen in the general population. Taking data from veterans out of the mix, the study found people in the general population with a PTSD diagnosis were twice as likely to develop dementia. The researchers hypothesize this finding may suggest active treatment for PTSD could reduce subsequent dementia risk, as veterans are much more likely to receive treatment for PTSD compared to members of the general population.

“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,” says senior author Vasiliki Orgeta. “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.”

It is unclear at this stage exactly what causal mechanisms could potentially explain this association between PTSD and dementia. The researchers hypothesize a number of possibilities, including the simple suggestion that PTSD can influence many behavioral factors that are known to amplify dementia risk, from depression to addiction.

“Constant hypervigilance and recurrent re-experiencing of the trauma may activate threat and stress-related neurobiological pathways, increasing vulnerability to dementia,” the researchers also hypothesize in the study. “As PTSD symptoms develop, avoidance and withdrawal from daily and social life may result in diminished cognitive stimulation, reducing individuals’ cognitive reserve and resilience to neuropathological changes associated with dementia. PTSD and dementia may also share common underlying genetic vulnerability, with pathways between the two being bidirectional.”

Perhaps the most important question the study raises is whether treating PTSD early can significantly delay, or even prevent, the onset of dementia. If PTSD is a notable risk factor for dementia then it certainly is something that is somewhat treatable. Alongside pre-existing therapies, the extraordinarily promising final phase trial data from MDMA-assisted psychedelic psychotherapy suggests early treatment can send the condition into remission.

The new study was published in the British Journal of Psychiatry.

Source: University College London

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