Children of alcoholics (COAs) are at elevated risk to develop alcohol and other substance use disorders. The neurobiological underpinnings of this heightened vulnerability are presently not well understood. This study investigated whether, in humans, COAs have different functioning of the mesolimbic reward circuitry beyond prior substance use confounds, and examined potential group differences in neural response in relation to alcohol use and behavioral risk. We studied twenty 18 to 22 year-old COAs and 20 controls, developmentally well-characterized for substance use and selected to match on sex, age, IQ, lifetime substance use and associated problems, and precursive (age 12–14) externalizing behavioral risk. None met criteria for DSM-IV diagnosis. Neural responses to anticipation of reward and loss were assessed using functional magnetic resonance imaging during a monetary incentive delay task. Overall, COAs showed reduced ventral striatum activation during anticipation of monetary reward and loss compared to controls. However, further analysis revealed that blunted nucleus accumbens (NAcc) response was only observed in COAs who have not demonstrated any problem drinking behavior. In addition, uniquely in COAs, NAcc activation was positively correlated with precursive externalizing risk, as well as current and lifetime alcohol consumption. These findings suggest a multilevel developmental process whereby lower precursive behavioral risk appears protective of later problem alcohol use in COAs, which is further associated with a blunted NAcc response to incentive anticipation, potentially reflecting a resilience mechanism. Moreover, the results suggest a close association between motivational responses, alcohol consumption, and behavioral risk, may underlie addiction vulnerability in COAs.

Recent research has suggested that marijuana use is associated with volumetric and shape differences in subcortical structures, including the nucleus accumbens and amygdala, in a dose-dependent fashion. Replication of such results in well controlled studies is essential to clarify the effects of marijuana. To that end, this retrospective study examined brain morphology in a sample of adult daily marijuana users (n ϭ 29) versus nonusers (n ϭ 29) and a sample of adolescent daily users (n ϭ 50) versus nonusers (n ϭ 50). Groups were matched on a critical confounding variable, alcohol use, to a far greater degree than in previously published studies. We acquired high-resolution MRI scans, and investigated group differences in gray matter using voxel-based morphometry, surface-based morphometry, and shape analysis in structures suggested to be associated with marijuana use, as follows: the nucleus accumbens, amygdala, hippocampus, and cerebellum. No statistically significant differences were found between daily users and nonusers on volume or shape in the regions of interest. Effect sizes suggest that the failure to find differences was not due to a lack of statistical power, but rather was due to the lack of even a modest effect. In sum, the results indicate that, when carefully controlling for alcohol use, gender, age, and other variables, there is no association between marijuana use and standard volumetric or shape measurements of subcortical structures.

Background Altered functional connectivity in critical networks has been associated with chronic alcohol abuse. In turn, changes in connectivity in executive control networks may undermine the ability to control alcohol consumption. It was hypothesized that network connectivity would be reduced in individuals with problematic alcohol use (ALC) compared to controls and that diminished network connectivity would be associated with greater failure to control drinking. Methods Resting state functional magnetic resonance imaging was analyzed to identify fourteen previously identified intrinsic connectivity networks (ICNs) using a priori regions of interest in cases ranging from binge drinkers to those with severe alcohol use disorder, as well as control subjects. Analyses tested for differences in network connectivity strength between 255 ALC cases and 87 age- and gender-matched controls. Further, structural equation analysis, using 383 ALC cases, tested whether functional connectivity strength mediated the relationship between years of regular drinking and alcohol problems. Results The age- and gender-matched analysis showed that ALC had significantly lower network connectivity strength than controls in the left executive control (LECN), basal ganglia (BG) and primary visual (PV) networks. For all ALC, LECN connectivity strength in negatively correlated with failed control and alcohol disorder severity. Edges connecting parietal regions with dorsolateral prefrontal, middle frontal and temporal regions within the LECN drove these relationships. A positive association between years of drinking and severity of alcohol problems was mediated by reduced executive control network connectivity. Conclusions This study reports relationships between network strength and problematic alcohol use, suggesting that chronic drinking negatively impacts brain connectivity, specifically in the left executive control network. Altered functional connectivity, related to chronic alcohol abuse, may contribute to the etiology of alcohol dependence and relapse.

BACKGROUND Differences in fronto-striatal connectivity in problem substance users have suggested reduced influence of cognitive regions on reward-salience regions. Youth with a family history of alcoholism (FH+) have disrupted ventral striatal processing compared with controls with no familial risk (FH−). As sensation-seeking represents an additional vulnerability factor, we hypothesized that functional connectivity during reward anticipation would differ by family history, and would mediate the relationship between sensation-seeking and drinking in high-risk subjects. METHODS Seventy 18–22 year olds (49 FH+/21 FH−) performed a monetary incentive delay task during functional magnetic resonance imaging. Group connectivity differences for incentive (reward/loss) vs. neutral conditions were evaluated with psychophysiological interaction (PPI) analysis, seeded in nucleus accumbens (NAcc). Indirect effects of sensation-seeking on drinking volume through accumbens connectivity were tested. RESULTS NAcc connectivity with paracentral lobule/precuneus and sensorimotor areas was decreased for FH− versus increased for FH+ during incentive anticipation. In FH+, task-related functional coupling between left NAcc and supplementary sensorimotor area (SSMA) and right precuneus correlated positively with sensation-seeking and drinking volume and mediated their relationship. In FH−, left NAcc-SSMA connectivity correlated negatively with sensation-seeking but was not related to drinking. CONCLUSIONS These results suggest preexisting differences in accumbens reward-related functional connectivity in high-risk subjects. NAcc coupling with SSMA, involved in attention and motor networks, and precuneus, a default mode structure, appear to mediate sensation-seeking’s effect on drinking in those most at-risk. Differences in accumbens connectivity with attention/motor/default networks, rather than control systems, may influence the reward system’s role in vulnerability for substance abuse.

Altered functional connectivity has been associated with acute and chronic nicotine use. Connectivity alterations, specifically in the right and left executive control networks (RECN/LECN) and the default mode network (DMN), may contribute to the addiction cycle. The objective of this study was to determine if ECN and DMN connectivity is different between non-smokers and smokers and whether reductions in connectivity are related to chronic cigarette use. The RECN, LECN and DMN were identified in resting state functional magnetic resonance imaging data in 650 subjects. Analyses tested for group differences in network connectivity strength, controlling for age and alcohol use. There was a significant group effect on LECN and DMN connectivity strength with smokers (n=452) having lower network strengths than non-smokers (n=198). Smokers had lower connectivity than non-smokers associated with key network hubs: the dorsolateral prefrontal cortex (DLPFC) and parietal (PAR) nodes within ECNs. Further, ECN connectivity strength was negatively associated with pack years of cigarette use. Our data suggest that chronic nicotine use negatively impacts functional connectivity within control networks that may contribute to the difficulty smokers have in quitting.