A pilot study investigating cognitive impairment associated with opioid overdose

Abstract

Background: In 2021, while overdose (OD) deaths were at the highest in recorded history, it is estimated that >80% of ODs do not result in a fatality. While several case studies have indicated that opioid-related ODs can result in cognitive impairment, the possible association has not yet been systematically investigated.

Methods: 78 participants with a history of OUD who reported experiencing an OD in the past year (n=35) or denied a lifetime history of OD (n=43) completed this study. Participants completed cognitive assessments including the Test of Premorbid Functioning (TOPF) and the NIH Toolbox Cognition Battery (NIHTB-CB). Comparisons were made between those who experienced an opioid-related OD in the past year versus those who denied a lifetime OD history while controlling for factors including age, premorbid functioning, and number of prior ODs.

Results: When comparing those who experienced an opioid-related OD within the past year to those without a history of OD, uncorrected standard scores were generally comparable; however, differences emerged in the multivariable model. Specifically, compared to those without a history of OD, those who experienced a past year OD evidenced significantly lower total cognition composite scores (coef. = -7.112; P=0.004), lower crystalized cognition composite scores (coef. = -4.194; P=0.009), and lower fluid cognition composite scores (coef. = -7.879; P=0.031).

Conclusions: Findings revealed that opioid-related ODs may be associated with, or contribute to, reduced cognition. Extent of the impairment appears contingent upon individuals' premorbid intellectual functioning and the cumulative number of past ODs. While statistically significant, clinical significance may be limited given that performance differences (∼4 - 8 points) were not particularly robust. More rigorous investigation is warranted, and future studies must also account for the many other variables possibly contributing to cognitive impairment.

Keywords: Cognition; Cognitive impairment; Opioid use disorder; Overdose; Substance toxicity.