The finding holds true when PTSD vets were compared to non-PTSD vets who suffered traumatic injuries during combat.
Exposure to life-threatening events, like war, can cause PTSD, and there are high rates among veterans. PSTD includes symptoms such as avoiding things or people that remind a person of the trauma, nightmares, difficulty with sleep, and mood problems.
“We found veterans with PTSD had twice the chance for later being diagnosed with dementia than veterans without PTSD,” said Mark Kunik, M.D., M.P.H., senior author of the article.
“Although we cannot at this time determine the cause for this increased risk, it is essential to determine whether the risk of dementia can be reduced by effectively treating PTSD. This could have enormous implications for veterans now returning from Iraq and Afghanistan.”
The study included 10,481 veterans at least 65 years of age who had been seen at the VA Medical Center at least twice between 1997 and 1999. Outpatient data were gathered for all identified patients until 2008.
Subjects who had been wounded during combat (with and without a PTSD diagnosis) were also identified to provide a group with confirmed injuries and combat experience. A group with two visits, but no PTSD or combat related injuries, was identified for purposes of comparison.
36.4 percent of the veterans in this study had PTSD. Of this group, dementia was diagnosed in 11.1 percent of individuals who were not injured. Dementia was also found in in 7.2 percent of those with PTSD who had been injured.
As a comparison, dementia was found in 4.5 percent of noninjured and 5.9 percent of injured non-PTSD groups.
These results remained significant after other risk factors of dementia were taken into account like diabetes, hypertension, heart disease, stroke, etc.
“Despite the increased risk for those with PTSD, it is noteworthy that most veterans with PTSD did not develop dementia during the period we studied,” said Salah Qureshi, M.D., a staff psychiatrist and investigator and first author of the article.
“It will be important to determine which veterans with PTSD are at greatest risk and to determine whether PTSD induced by situations other than war injury is also associated with greater risk.”
The authors note there could be several explanations for their findings. It could be that cognitive impairment in PTSD is an early marker of dementia, having PTSD makes one more likely to get dementia, or PTSD and dementia have some characteristics in common.
They emphasize the need for further study with a broader sample in the civilian population.
In an editorial accompanying this paper, Dr. Soo Borson of the University of Washington Medical Center, Washington, highlights the need for further research to explain the association and also the wider significance of these findings.
“Confirmation of a causal link between PTSD and cognitive impairment in late life would have enormous global implications in a world facing a rising societal burden of dementia, a shrinking workforce to sustain its economies, and the difficulties of containing human violence.
“Soldiers and other U.S. war veterans are just one of many groups exposed to deeply traumatizing experiences with lifetime effect.”
The research is reported in the Journal of the American Geriatrics Society.