By Kevin Jiang, Harvard Medical School
April 9, 2019
Among the most common health-related concerns for returning U.S. combat veterans is worsened cognitive performance, including difficulties with attention, memory, planning, and decision-making, which can make adjusting to civilian life more difficult.
The underlying causes of these deficits, collectively termed cognitive dysfunction, are still unclear, but they have sometimes been attributed to neurological damage from mild traumatic brain injuries or even accelerated physical aging processes related to stress.
However, a new study finds that for veterans of the Afghanistan and Iraq wars there is little to no association between cognitive dysfunction and age, mild traumatic brain injury, or other physiological and neural measures. Instead, cognitive performance issues appear to be strongly associated with psychological distress, including depression, anxiety, and symptoms of post-traumatic stress disorder.
The results of the study, led by researchers at Harvard Medical School and VA Boston Healthcare System, suggest that treatments that address psychological distress can help improve cognitive function for combat veterans and other trauma-exposed populations.
The findings were published online in Neuropsychology on April 4.
“Many veterans who are deployed to combat zones return home with cognitive complaints. They say their memory is worse, that they can’t focus or concentrate, which can cause problems in daily life,” said study author Joseph DeGutis, HMS assistant professor of psychiatry at VA Boston Healthcare.
Often, veterans are led to believe that these issues are due to neurological problems such as mild traumatic brain injuries sustained from a blast or blunt force injury, DeGutis said.
“Our study indicates that those with and without cognitive dysfunction have very similar neural and physiological health but differ in terms of psychological distress and related issues of alcohol consumption, chronic pain, and poor sleep,” he continued. “This suggests that if more veterans were treated for psychological distress, we could see improved outcomes for cognitive dysfunction and associated daily life issues.”
In their study, DeGutis and colleagues examined the psychological and physical profiles of 368 veterans who were exposed to combat during deployments in Iraq and Afghanistan. Study participants were on average 32 years of age and 90 percent were men. All were enrolled through the Translational Research Center for Traumatic Brain Injury and Stress Disorders (TRACTS) at VA Boston Healthcare.
The researchers assessed cognitive performance through a battery of well-validated tests, including multiple measures of attention, memory and executive function—the ability to plan, organize and prioritize tasks. Based on the tests, participants were assigned scores for cognitive performance.
A little over a third of the participants, 129 in total, were identified as having clinically significant cognitive dysfunction, which was defined as a score below a cutoff derived from the American Psychiatric Association’s Diagnostic and Statistical Manual (DSM-5) diagnosis for neurocognitive disorder.
To study the differences between veterans with cognitive dysfunction and those without, DeGutis and colleagues assessed brain health through MRI scans measuring cortical thickness and interviews to determine the participants’ histories of mild traumatic brain injuries and blast exposures.
The researchers evaluated a wide variety of measures for clinical, neural and psychological health. This included self-reported assessments of daily life function, including social participation, communication, self-care, and others. They also examined participants’ premorbid reading ability to assess intellectual functioning before potential exposure to trauma.
The team’s analyses revealed that veterans with cognitive dysfunction had more severe measures of psychological distress, including increased anxiety, depression, PTSD, sleep difficulties, pain and alcohol consumption, compared to those without. These veterans also had lower scores on their premorbid reading ability tests, suggesting that trauma-related psychological distress symptoms may exacerbate existing cognitive dysfunction, according to the study authors.
In contrast, the team found weak or no association between cognitive dysfunction and age, traumatic brain injury, and other physical health and neural measures that they assessed.
While decreased cognitive performance among veterans has been previously reported, the prevalence and the profile of trauma-exposed individuals with clinically significant cognitive dysfunction has remained incompletely characterized. The new findings now shed light on both and provide a clinical and psychological characterization of veterans with cognitive dysfunction. The team is now studying whether cognitive function for combat veterans can be improved through treatments for psychological distress.
“I think as a society, we still have a blind spot. Often, we are more sympathetic towards those with a physical issue like a brain injury than those experiencing psychological distress, particularly in the military,’” DeGutis said.
“These results can help us reframe the conversation we have with combat veterans, because many aspects of psychological distress are treatable,” he said. “It’s clear that issues like depression, drinking, chronic pain or poor sleep can impact both cognitive and daily life functioning, and treating these issues should help improve outcomes.”
Additional authors on the study include Elizabeth Riley, Alex Mitko, Anna Stumps, Meghan Robinson, William Milberg, Regina McGlinchey, and Michael Esterman.
The study was supported by the U.S. Department of Veterans Affairs through the VA Boston Translational Research Center for TBI and Stress Disorders, a VA Rehabilitation Research and Development Traumatic Brain Injury Center of Excellence (B9254-C). DOI: 10.1037/neu0000529