Since 2000, more than 300,000 members of the US military have sustained a traumatic brain injury—largely from improvised explosive devices in Iraq and Afghanistan.

Most of them have since come home—to families, communities, and the job market. But approximately 45 percent of them are now unemployed.

That figure comes from a new study led by BU School of Public Health researcher Terri K. Pogoda, a research assistant professor of health policy and management. The study shows that the veterans’ conditions are making it difficult for them to find and retain jobs, suggesting that they need multifaceted help to readjust to civilian life.

The study, published last month in the Journal of Head Trauma Rehabilitation, finds that almost half of veterans evaluated for traumatic brain injury (TBI) at the Department of Veterans Affairs (VA) and diagnosed with a moderate to severe form, were unemployed, compared to about a third of those with mild TBI or no TBI history. Also, more than 80 percent had at least one suspected psychiatric condition, such as post-traumatic stress disorder (PTSD), anxiety, or depression, and 42 percent had two or more such conditions.

Those bleak findings “underscore the need to investigate why unemployment rates are high among this cohort, and what assistance can be provided to address veterans’ multiple needs,” the research team concludes.

Lead author Pogoda, who is also a researcher with the VA Boston’s Center for Healthcare Organization and Implementation Research, notes that the VA offers benefits to veterans who want to pursue academic, training, and vocational rehabilitation programs—services that may be particularly useful to those who have a high school education or less—but that this may not be enough.

“Simultaneously addressing health-related and psychiatric needs may fill a critical gap for helping veterans readjust to civilian life and achieve their academic and vocational potential,” she says.

TBI is a so-called signature injury of the Iraq and Afghanistan wars caused by blasts from improvised explosive devices, but it also results from nonblast injuries such as motor vehicle crashes, falls, or other blunt force traumas. Mild TBI is the most common type, accounting for more than 80 percent of all cases treated. Symptoms of TBI include cognitive and neuropsychological impairment.

The study finds that overall, about a third of 11,000 veterans evaluated for TBI were unemployed—a figure that far surpasses unemployment rates in the civilian workforce. Patients with mild forms of TBI were no more likely to be unemployed than those who screened negative for TBI.

But the veterans who were unemployed and not looking for work, the researchers find, were more likely to have experienced moderate to severe TBI. In addition, they were more likely to have lower education levels, to suffer from suspected PTSD or another psychiatric condition, to be age 40 or older, and to be divorced, separated, or widowed. Also, active-duty veterans were more likely to be unemployed than those who served in the National Guard/Reserves.

The researchers note that PTSD, anxiety, and substance use disorders have all been linked to lower rates of employment among veterans. Traumatic brain injuries may complicate those connections, triggering or aggravating mental health problems.

“Substance use has been documented in a large proportion of individuals who have sustained TBI, and while preinjury substance use is common, there is evidence that TBI may also be a risk factor for this behavior,” according to the study.

Regardless of the timing of the onset of psychiatric conditions, the findings “underscore the importance of assessing and treating these conditions as a means of facilitating veterans in finding and maintaining work,” the researchers write.

The unemployment rate for veterans who have served since 2001 was 9 percent in 2013—down slightly from the year before, but well above the civilian rate of 7 percent, according to the US Labor Department’s Bureau of Labor Statistics, in a report released earlier this year. The youngest veterans, ages 18 to 24, posted an ultrahigh jobless rate of 21.4 percent.

The Labor Department report documents that despite training and job skills acquired in the military, young veterans of recent conflicts have generally encountered more difficulty in finding work than civilians. It also shows that 29 percent of veterans serving since 2001 report having a service-connected disability.

Pagoda’s study concludes that further investigation is required to find “why unemployment rates are high among this cohort,” those with moderate to severe TBIs, and what interventions might best address the veterans’ needs.

In addition to Pogoda, the TBI study team comprised researchers from the BU School of Medicine, Virginia Commonwealth University, the University of Hawaii at Manoa, the Defense Resources Management Institute, and the National Center for Post-traumatic Stress Disorder.