Veterans with mild brain injury history show cognitive deficits in line with early Parkinson’s Disease patients

Mar 12

By Conor Gormally. This article was initially published in our Concussion Update newsletter; please consider subscribing.

A study by Vicki A. Nejtek et al., published in PLOS One, conducted cognitive examinations with “age- and IQ-matched veterans with and without mTBI [mild traumatic brain injury history], non-veteran healthy controls, and IQ-matched non-demented early-stage PD [Parkinson’s Disease]” patients. They found that veterans with mTBI history performed significantly worse on 4 of 9 cognitive tests than either the age-matched non mTBI veterans or the healthy controls. Concerningly, the test results for veterans with mTBI showed they were cognitively “at least three decades older.” They performed most closely to the cohort of early-stage Parkinson’s Disease patients.

According to an article in Neurology Today by Dan Hurley, the research team wanted to include early-stage PD patients based on a 2018 finding that veterans with mTBI history had an increased risk of developing PD “within six or seven years.” Average service length was 9.04 +/- 5.6 years for mTBI veterans and 8.13 +/- 3.9 years for non-mTBI veterans.

The primary outcome researchers looked at was the results of the Trail Making Test (TMT A and TMT B), which assesses “cognitive flexibility, attention, processing speed, memory, and inhibitory control.” Longer TMT times indicate poorer cognitive functioning. The researchers found no statistically significant TMT completion time difference between veterans with mTBI and PD patients, with both groups performing significantly worse than veterans without mTBI and civilian controls.

Nejtek et al. observed that “veterans (+) mTBI significantly lagged behind their age- and IQ-matched controls, performed more like older, early-stage PD subjects and presented cognitively as if they were at least three decades older on tests of cognitive flexibility, attention, processing speed, and inhibitory control.” However, they acknowledge that their study is not designed to draw any links between mTBI and PD or capture risk factors for PD development in veterans with mTBI history.