Gregg Zoroya

USA TODAY

A survey of several hundred veterans with mild brain injury, most coming in combat and from exposure to blast, shows that 60% reported suffering a neurological condition that involves exaggerated emotional responses such as crying or laughing.

"We were little surprised by the findings for this population," said Regina McGlinchey, director of the Translational Research Center for TBI and Stress Disorders at a VA hospital in Boston. "We didn't expect to see that high of a prevalence."

It is possible that many combat veterans suffer from the affliction but do not talk about it, she said.

The research was a collaboration between the Department of Veterans Affairs and a pharmaceutical company that manufactures a drug to treat the conditions. Findings will be presented Friday at the 10th World Conference on Brain Injury in San Francisco.

Researchers conducted an e-mail survey of 4,283 veterans in the New England area last year who had tested positive for mild traumatic brain injury after being previously screened by the VA. A total of 758 answered the survey, a 19% response rate that researchers say is positive in this type of study.

Six out of 10 of those with mild TBI cases reported suffering from pseudobulbar affect or PBA, a neurological condition that often afflicts those with brain ailments such as TBI, ALS, Alzheimer's or dementia, said Joao Siffert, head of research for the drug company, Avanir Pharmaceuticals Inc.

Avanir produces the drug Nuedexta, which is designed to reduce the frequency of PBA and has been on the market since 2011, Siffert said.

Those with PBA can display involuntary and uncontrolled episodes of crying or laughing, he said.

"This is not a psychiatric issue. It's a neurological issue," McGlinchey said. "The debilitating part is that those outbursts can really occur in socially inappropriate times. It's very difficult on families and obviously on the patients themselves. ... It just gives us another piece of the puzzle and helps us understand a little bit better the range of problems the TBI cohort has."