Presumed structural and functional neural recovery after long-term abstinence from cocaine in male military veterans

Abstract

Cumulative evidence suggests that cocaine use could alter the structure and function of different brain systems. However, the extent to which the altered brain structure and function possibly recover over time after cocaine abstinence remains less clear. The present study examines 39 male military veterans with different stages of cocaine addiction and long-term abstinence (from 1 year up to 30 years) and evaluates plausible changes in brain structure and function of specific brain regions that sub-serve addictions. These include the striatum that is involved in cocaine reward; the lateral prefrontal cortex (especially the dorsolateral PFC) that plays a major role in inhibitory control; the insula, which has been implicated in craving; and the medial orbitofrontal (OFC) and ventromedial prefrontal cortex (VMPFC) shown to play key roles in foresight and decision-making. The results suggest that there are differences in both brain structure (gray matter volume, GMV) and function between cocaine USERS and CONTROLS, with USERS showing plausible relative strengthening in neural systems for processing reward and craving, and relative weakening in neural systems involved in inhibitory control and decision-making. Examination of possible neural changes after abstinence suggests that presumed recovery occurs mostly in neural systems related to reward, craving, and inhibitory control, but to a lesser extent in neural systems related to decision-making. Given the limitations of the data in terms of a small sample size, as well as the lack of certainty about occasional use in the abstinent group, these results may be considered as preliminary. However, they are compelling in that they suggest that male military veterans cocaine USERS are indefinitely at a higher risk compared to CONTROLS for making lapses in judgment and decision-making leading to possible relapse, if reward salience and craving become more intense. Understanding the neurobiology of long-term cocaine abstinence in vulnerable populations and beyond could help devising better therapeutic strategies that prevent relapse.

Keywords: Abstinence; Cocaine addiction; Functional connectivity; VBM; fMRI.