Lifetime Opioid Exposure and Neurocognitive Performance Among a Sample of Combat Veterans With and Without Mild Traumatic Brain Injury

Abstract

Introduction: Veterans with traumatic brain injuries (TBIs) may have a heightened risk of neurocognitive impairment and early onset of neurodegenerative diseases. Exposure to opioid analgesics may also be associated with a reduction in neurocognitive function. To understand the potential interplay between TBI and opioid exposure on neurocognitive performance, we measured associations between lifetime opioid exposure and neurocognitive performance and examined potential interaction/effect measure modification by Veterans' mild TBI (mTBI) history.

Materials and methods: Participants included combat Veterans enrolled at the Veterans Affairs Portland Health Care System site of the Long-term Impact of Military-Relevant Brain Injury Consortium/Chronic Effects of Neurotrauma Consortium (LIMBIC-CENC) prospective longitudinal study. Lifetime opioid exposure was measured using survey responses and prescription data and was categorized as moderate/high versus low/no. Neurocognitive performance was measured using 9 neuropsychological component test scores. Associations between lifetime opioid exposure and neurocognitive performance were estimated using bivariable and multivariable linear regression models; multivariable models controlled for demographic, military, and clinical characteristics. Stratified analyses were performed to examine associations by mTBI history.

Results: Of 282 participants, 84 (29.8%) had moderate or high lifetime opioid exposure and 198 (70.2%) had low or no lifetime opioid exposure; 31.3% had deployment-related mTBI history, 45.7% non-deployment-related mTBI, and 33.0% no mTBI. There were no associations between lifetime opioid exposure and neurocognitive performance. However, among participants with deployment-related mTBI, those with moderate or high lifetime opioid exposure demonstrated improved performance on executive functioning neuropsychological component tests compared to those with low or no lifetime opioid exposure.

Conclusions: Although lifetime opioid exposure did not appear to be significantly associated with neurocognitive performance among this sample of Veterans, there are indications that the relationship between opioid exposure and neurocognitive function is modified by deployment-related mTBI history. Continued research exploring the interplay between mTBI and opioid exposure on neurocognitive performance is needed.