Reduced Functional Connectivity within the Mesocorticolimbic System in Substance Use Disorders: An fMRI Study of Puerto Rican Young Adults

Abstract

Studies of the mesocorticolimbic reward system (MCLS) and its relationship with impulsivity and substance use disorders (SUD) have largely focused on individuals from non-minority backgrounds. This represents a significant gap in the literature particularly for minority populations who are disproportionately affected by the consequences of SUD. Using resting-state functional MRI (fMRI), we examined the coherence of neural activity, or functional connectivity, within the brain's MCLS in 28 young adult Puerto Ricans (ages 25-27) who were part of a population-based cohort study. Half of the sample lived in San Juan, Puerto Rico; the other half lived in the South Bronx, New York. At each of the two sites, half of the sample had a history of a SUD. Relative to those without SUD, individuals with SUD had decreased connectivity between the nucleus accumbens (NAcc) and several regions within the MCLS. This finding was true irrespective of study site (i.e., San Juan or South Bronx). Reduced connectivity within the MCLS was also associated with higher selfreported levels of impulsivity. Path analysis suggested a potential mechanism linking impulsivity, the MCLS, and SUD: impulsivity, potentially by chronically promoting reward seeking behaviors, may contribute to decreased MCLS connectivity, which in turn, may confer vulnerability for SUD. Expanding upon prior studies suggesting that alterations within the MCLS underlie SUD, our findings suggest that such alterations are also related to impulsivity and are present in a high-risk young minority population.

Increased functional connectivity between the default mode and salience networks in unmedicated adults with obsessive-compulsive disorder

“…In other words, a significant relationship between OCD and sustained attention should first be established prior to examining potential mediators of this relationship. However, path can occur regardless of whether a direct effect is statistically significant [Hayes, ; Posner et al, ]. This is particularly true when (a) the power to detect a direct relationship is limited, (b) several mediators may be influencing the direct relationship, and (c) the indirect relationship (i.e., from IV to mediator, and then mediator to DV) is statistically significant [Hayes, ].…”

A critical scoping review about the impact of music in the lives of young adults who use drugs

“…More specifically, problematic PAS use is strongly associated with emotional regulation difficulties and, consequently, with the experience of negative emotions, including depressive symptoms [27]. These severe consequences result from the effect of PAS on users' neuronal pathways, including dopaminergic and endorphin pathways, which become dysregulated upon repeated PAS use [28–31].…”

“…dopaminergic and serotonin) as well as that of the endorphin and opioid pathways, which are involved in the modulation of physical states [48–50]. Hence, it is plausible that music may contribute to improve the global well‐being when it is compromised by the dysregulation of these neuronal pathways, as is the case in individuals who suffer problematic PAS use [28–30]. Yet, research suggest that music may also cause harm, specifically in relation to PAS use, including its initiation, progression and relapse [51–56].…”