Brandon Barton, MD, a neurologist at the Jesse Brown VA Medical Center in Chicago, and colleagues analyzed data for 105,193 US veterans with Parkinson’s disease. “VA databases are large, well organized, and provide access to subject identification and health history in a unique way that is not otherwise available in other health care systems,” stated Dr. Barton. “We hypothesized that veterans with Parkinson’s disease have a high prevalence of cognitive deficits, and that those with any of the three target exposures [Agent Orange, TBI, and PTSD] have more frequent cognitive diagnoses than those without exposure.”
According to the investigators, cognitive-related diagnoses varied widely among the veterans with Parkinson’s disease. About 60% of cases were attributable to nonspecific disorder (ie, mental disorder, not otherwise specified), Alzheimer’s disease, or senile dementia. Veterans with Parkinson’s disease who also had PTSD, Agent Orange exposure, or a history of TBI had a higher prevalence of cognitive diagnosis, compared with veterans without a similar history.Veterans were eligible for inclusion if they had more than two diagnostic codes of Parkinson’s disease between 2003 and 2012. Cognitive diagnoses were based on the list of all possible cognitive ICD-9 diagnoses. Participating veterans served in World War II, Korea, Vietnam, or in post-Vietnam wars. Their average age was 74, 87.9% were Caucasian, and 98.4% were male.
Dr. Barton pointed out that “Parkinson’s disease dementia” was not an available code during the study period and that Parkinson’s disease–related cognitive deficits were coded in various ways.
“Future analysis of the [effects of] comorbidities on cognitive symptoms and cognitive factors related to wartime exposures is warranted,” Dr. Barton commented.