Mapping brain volumetric abnormalities in never-treated pathological gamblers

Neuronal activation of nucleus accumbens by local methamphetamine administration induces cognitive impairment through microglial inflammation in mice

More than half of methamphetamine (METH) users present with cognitive impairment, making it difficult for them to reintegrate into society. However, the mechanisms of METH-induced cognitive impairment remain unclear. METH causes neuronal hyperactivation in the nucleus accumbens (NAc) by aberrantly releasing dopamine, which triggers dependence. In this study, to clarify the involvement of hyperactivation of NAc in METH-induced cognitive impairment, mice were locally microinjected with METH into NAc (mice with METH (NAc)) and investigated their cognitive phenotype. Mice with METH (NAc) exhibited cognitive dysfunction in behavioral analyses and decreased long-term potentiation in the hippocampus, with NAc activation confirmed by expression of FosB, a neuronal activity marker. In the hippocampus of mice with METH (NAc), activated microglia, but not astroglia, and upregulated microglia-related genes, Il1b and C1qa were observed. Finally, administration of minocycline, a tetracycline antibiotic with suppressive effect on microglial activation, to mice with METH (NAc) ameliorated cognitive impairment and synaptic dysfunction by suppressing the increased expression of Il1b and C1qa in the hippocampus. In conclusion, activation of NAc by injection of METH into NAc elicited cognitive impairment by facilitating immune activation in mice. This study suggests that immunological intervention could be a therapeutic strategy for addiction-related cognitive disturbances.

Brain morphometry in adults with gambling disorder

Little is known regarding the brain substrates of Gambling Disorder, including surface brain morphometry, and whether these are linked to the clinical profile. A better understanding of the brain substrates will likely help determine targets to treat patients. Hence, the aim of this study was two-fold, that is to examine surface-based morphometry in 17 patients with gambling disorder as compared to norms of healthy individuals (2713 and 2790 subjects for cortical and subcortical anatomical scans, respectively) and to assess the clinical relevance of morphometry in patients with Gambling Disorder. This study measured brain volume, surface and thickness in Gambling Disorder. We compared these measures to those of a normative database that controlled for factors such as age and sex. We also tested for correlations with gambling-related behaviors, such as gambling severity and duration, impulsivity, and depressive symptoms (assessed using the South Oaks Gambling Screen, years of gambling, Barratt Impulsiveness Scale, and Beck Depression Inventory, respectively). Patients displayed thinner prefrontal and parietal cortices, greater volume and thickness of the occipital and the entorhinal cortices, and greater volume of subcortical regions as compared to the norms of healthy individuals. There were positive correlations between surface area of occipital regions and depressive symptoms. This work contributes to better characterize the brain substrates of Gambling Disorder, which appear to resemble those of substance use disorders and Internet Gaming Disorder.

The neural basis of gambling disorder: An activation likelihood estimation meta-analysis

Previous imaging studies suggested that impairments of prefrontal-striatal and limbic circuits are correlated to excessive gambling. However, the neural underpinnings of gambling disorder (GD) continue to be the topic of debate. The present study aimed to identify structural changes in GD and differentiate the specific brain activity patterns associated with decision-making and reward-processing. We performed a systematic review complemented by Activation likelihood estimation (ALE) meta-analyses on morphometric and functional studies on neural correlates of GD. The ALE meta-analysis on structural studies revealed that patients with GD showed significant cortical grey-matter thinning in the right ventrolateral and ventromedial prefrontal cortex compared to healthy subjects. The ALE meta-analyses on functional studies revealed that patients with GD showed a significant hyperactivation in the medial prefrontal cortex and in the right ventral striatum during decision-making and gain processing compared to healthy subjects. These findings suggest that GD is related to an alteration of brain mechanisms underlying top-down control and appraisal of gambling-related stimuli and provided indications to develop new interventions in clinical practice.

Gray Matter Volume Differences in Impulse Control and Addictive Disorders-An Evidence From a Sample of Heterosexual Males

BACKGROUNDS

The classification of addictions and impulse control disorders is changing as reflected in the 11th version of International Classification of Disorders (WHO, 2018). However, studies focusing on direct comparison of structural brain differences in behavioral and substance addictions are limited.

AIM

Here, we contrast gray matter volumes (GMVs) across groups of individuals with compulsive sexual behavior disorder (CSBD), gambling disorder (GD), and alcohol use disorder (AUD) with those with none of these disorders (healthy controls participants; HCs).

METHODS

Voxel-based morphometry was used to study brain structure, and severities of addiction symptoms were assessed with questionnaires. To identify brain regions related to severities of addictions, correlations between questionnaire scores and GMVs were computed.

MAIN OUTCOME

We collected magnetic resonance imaging (GMVs) data from 26 patients with CSBD, 26 patients with GD, 21 patients with AUD, and 25 HC participants (all heterosexual males; age: 24-60; mean = 34.5, standard deviation = 6.48).

RESULTS

Affected individuals (CSBD, GD, AUD) compared with HC participants showed smaller GMVs in the left frontal pole, specifically in the orbitofrontal cortex. The most pronounced differences were observed in the GD and AUD groups, and the least in the CSBD group. In addition, a negative correlation was found between GMVs and disorder severity in the CSBD group. Higher severity of CSBD symptoms was correlated with decreased GMVs in the right anterior cingulate gyrus.

CLINICAL IMPLICATIONS

Our findings suggest similarities between CSBD and addictions.

STRENGHS AND LIMITIATIONS

This study is the first showing smaller GMVs in 3 clinical groups of CSBD, GD, and AUD. But the study was limited only to heterosexual men. Longitudinal studies should examine the extent to which ventral prefrontal decrements in volume may represent preexisting vulnerability factors or whether they may develop with disorder progression.

CONCLUSIONS

Our research extends prior findings in substance use disorders of lower GMVs in prefrontal cortical volumes among 3 clinical groups of patients with specific impulse control (CSBD) and behavioral (GD) and substance (AUD) addictive disorders. The negative correlation between CSBD symptoms and GMV of right anterior cingulate gyrus suggests a link with clinical symptomatology. Draps M, Sescousse G, Potenza MN, et al. Gray Matter Volume Differences in Impulse Control and Addictive Disorders-An Evidence From a Sample of Heterosexual Males. J Sex Med 2020;17:1761-1769.

Common neurobiological and psychological underpinnings of gambling and substance-use disorders

Both psychological and neurobiological studies in gambling disorder have increased in the past 10-15 years. This review examines the current state of the literature, with a focus on recent magnetic resonance imaging (MRI) studies in gambling disorder. The review compares and contrasts findings across gambling and substance-use disorders. Additionally, features with arguably particular relevance to gambling disorder (e.g., "near-miss" processing) are described, as well as their relationship to choice behaviors. More broadly, the review informs on how these studies advance our understanding of brain-behavior relationships relating to decision-making and key features of addictive disorders.

Deficient Decision Making in Pathological Gamblers Correlates With Gray Matter Volume in Medial Orbitofrontal Cortex

Individuals suffering from pathological gambling (PG) show impaired decision making, but it is still not clear how this impairment is related to other traits and neuroanatomical characteristics. In this study, we investigated how the influence of PG on decision making (1) is connected to different impulsivity facets and (2) how it is related to gray matter volume (GMV) in various brain regions. Twenty-eight diagnosed PG patients and 23 healthy controls completed the cups task to measure decision making. In this task, participants had to decide between safe and risky options, which varied in expected value (EV) between risk advantageous, equal EV, and risk disadvantageous choices. A delay discounting task and the Barrant Impulsiveness Scale were applied to assess multiple impulsivity facets. In addition, structural magnetic resonance images were acquired. In comparison to the control group PG patients demonstrated more deficits in decision making, indicated by less EV sensitivity, but there was no significant difference in number of overall risky choices. Also, PG patients showed increased impulsivity in nearly every dimension. Results revealed (1) a positive correlation between decision making impairments and non-planning impulsivity but no significant relation to other impulsivity facets. Although we found no GMV differences between PG patients and controls, (2) a regions of interest analysis showed a correlation between medial orbitofrontal GMV and EV sensitivity in PG patients. Our findings showed that (1) the association between decision making and impulsivity can also be found in PG patients, but only for certain impulsivity facets. This suggests that it is essential to consider measuring different dimensions, when investigating impulsivity in a PG sample. Secondly, our findings revealed that (2) dysfunctional decision making-particularly the component of risk evaluation-is related to decreased GMV in the medial orbitofrontal cortex, a brain region concerned with processing of rewards. Interestingly, we did not find more risky choices for PG patients, and thus, we assume that decision making deficits in PG are primarily related to risk evaluation, not risk seeking, which is in line with our GMV findings.

Abnormalities of striatal morphology in gambling disorder and at-risk gambling

OBJECTIVE

The clinical phenotype of gambling disorder (GD) is suggestive of changes in brain regions involved in reward and impulse suppression, notably the striatum. Studies have yet to characterize striatal morphology (shape) in GD and whether this may be a vulnerability marker.

AIMS

To characterize the morphology of the striatum in those with disordered gambling (at-risk gambling and GD) versus controls.

METHOD

Individuals aged 18-29 years were classified a priori into those with some degree of GD symptoms (at-risk gambling and GD) or controls. Exclusion criteria were a current mental disorder (apart from GD), history of brain injury, or taking psychoactive medication within 6 weeks of enrollment. History of any substance use disorder was exclusionary. Participants completed an impulsivity questionnaire and structural brain scan. Group differences in volumes and morphology were characterized in subcortical regions of interest, focusing on the striatum.

RESULTS

Thirty-two people with GD symptoms (14 at-risk and 18 GD participants) and 22 controls completed the study. GD symptoms were significantly associated with higher impulsivity and morphological alterations in the bilateral pallidum and left putamen. Localized contraction in the right pallidum strongly correlated with trait impulsivity in those with GD symptoms.

CONCLUSIONS

Morphologic abnormalities of the striatum appear to exist early in the disease trajectory from subsyndromal gambling to GD and thus constitute candidate biological vulnerability markers, which may reflect differences in brain development associated with trait impulsivity. Striatal morphology and associated impulsivity might predispose to a range of problematic repetitive behaviors.

Altered orbitofrontal sulcogyral patterns in gambling disorder: a multicenter study

Gambling disorder is a serious psychiatric condition characterized by decision-making and reward processing impairments that are associated with dysfunctional brain activity in the orbitofrontal cortex (OFC). However, it remains unclear whether OFC functional abnormalities in gambling disorder are accompanied by structural abnormalities. We addressed this question by examining the organization of sulci and gyri in the OFC. This organization is in place very early and stable across life, such that OFC sulcogyral patterns (classified into Types I, II, and III) can be regarded as potential pre-morbid markers of pathological conditions. We gathered structural brain data from nine existing studies, reaching a total of 165 individuals with gambling disorder and 159 healthy controls. Our results, supported by both frequentist and Bayesian statistics, show that the distribution of OFC sulcogyral patterns is skewed in individuals with gambling disorder, with an increased prevalence of Type II pattern compared with healthy controls. Examination of gambling severity did not reveal any significant relationship between OFC sulcogyral patterns and disease severity. Altogether, our results provide evidence for a skewed distribution of OFC sulcogyral patterns in gambling disorder and suggest that pattern Type II might represent a pre-morbid structural brain marker of the disease. It will be important to investigate more closely the functional implications of these structural abnormalities in future work.

Neuroimaging of reward mechanisms in Gambling disorder: an integrative review

Gambling disorder (GD) was reclassified as a behavioral addiction in the DSM-5 and shares clinical and behavioral features with substance use disorders (SUDs). Neuroimaging studies of GD hold promise in isolating core features of the addiction syndrome, avoiding confounding effects of drug neurotoxicity. At the same time, a neurobiologically-grounded theory of how behaviors like gambling can become addictive remains lacking, posing a significant hurdle for ongoing decisions in addiction nosology. This article integrates research on reward-related brain activity (functional MRI) and neurotransmitter function (PET) in GD, alongside the consideration of structural MRI data as to whether these signals more likely reflect pre-existing vulnerability or neuroadaptive change. Where possible, we point to qualitative similarities and differences with established markers for SUDs. Structural MRI studies indicate modest changes in regional gray matter volume and diffuse reductions in white matter integrity in GD, contrasting with clear structural deterioration in SUDs. Functional MRI studies consistently identify dysregulation in reward-related circuitry (primarily ventral striatum and medial prefrontal cortex), but evidence is mixed as to the direction of these effects. The need for further parsing of reward sub-processes is emphasized, including anticipation vs outcome, gains vs. losses, and disorder-relevant cues vs natural rewards. Neurotransmitter PET studies indicate amplified dopamine (DA) release in GD, in the context of minimal differences in baseline DA D2 receptor binding, highlighting a distinct profile from SUDs. Preliminary work has investigated further contributions of opioids, GABA and serotonin. Neuroimaging data increasingly highlight divergent profiles in GD vs. SUDs. The ability of gambling to perpetually activate DA (via maximal uncertainty) may contribute to neuroimaging similarities between GD and SUDs, whereas the supra-physiological DA effects of drugs may partly explain differences in the neuroimaging profile of the two syndromes. Coupled with consistent observations of correlations with gambling severity and related clinical variables within GD samples, the overall pattern of effects is interpreted as a likely combination of shared vulnerability markers across GD and SUDs, but with further experience-dependent neuroadaptive processes in GD.

Gray-matter relationships to diagnostic and transdiagnostic features of drug and behavioral addictions

Alterations in neural structure have been reported in both cocaine-use disorder and gambling disorder, separately, suggesting similarities across addiction diagnoses. Individual variation in neural structure has also been associated with impulsivity, a dimensional construct implicated in addictions. This study combines categorical (diagnosis-based) and dimensional (transdiagnostic) approaches to identify neural structural alterations linked to addiction subtypes and trait impulsivity, respectively, across individuals with gambling disorder (n = 35), individuals with cocaine-use disorder (n = 37) and healthy comparison individuals (n = 37). High-resolution T1-weighted data were analyzed using modulated voxel-based morphometry (VBM). Statistical analyses were conducted using whole-brain general-linear models, corrected for family-wise error (pFWE < .05). Categorical analyses indicated a main effect of diagnostic group on prefrontal (dorsal anterior cingulate and ventromedial prefrontal cortex) gray matter volumes (GMVs), involving decreased GMVs among cocaine-use disorder participants only. Dimensional analyses indicated a negative association between trait impulsivity and cortical (insula) and subcortical (amygdala and hippocampus) GMVs across all participants. Conjunction analysis indicated little anatomical overlap between regions identified as differentiating diagnostic groups and regions covarying with impulsivity. These data provide first evidence of neural structural differences between gambling disorder and an illicit substance-use disorder. They further indicate dissociable effects of diagnostic groupings and trait impulsivity on neural structure among individuals with behavioral and drug addictions. Study findings highlight the importance of considering both categorical and dimensional (e.g. Research Domain Criteria; RDoC) analysis approaches within the context of addictions research.

Frontal cortex gray matter volume alterations in pathological gambling occur independently from substance use disorder

Neuroimaging in pathological gambling (PG) allows studying brain structure independent of pharmacological/neurotoxic effects occurring in substance addiction. Because of high comorbidity of PG with substance use disorder (SUD), first results on structural deficits in PG are controversial. The current investigation is the first to examine gray matter (GM) volume alterations in PG controlling for the impact of SUD by comparing non-comorbid (PG_PURE ) and two comorbid (PG_ALCOHOL and PG_POLY ) groups. Two hundred and five individuals were included in the analysis: 107 patients diagnosed with PG and 98 healthy controls (HCs). We employed voxel-based morphometry to look for GM volume differences between the groups controlling for age, smoking and depression. GM decreases in the superior medial and orbital frontal cortex occur independently of substance use in PG_PURE compared with HCs. The frontal pattern of GM decrease was comparable with PG_ALCOHOL group where additionally GM volume was decreased in the anterior cingulate but increased in the amygdala. Moreover, regions in PG_{ALCOHOL + POLY} with reduced GM volume were the medial frontal, anterior cingulate and occipital lobe regions. PG_{ALCOHOL + POLY} not only exhibited structural deficits in comparison with HCs but also relative to PG_PURE in the precuneus and post-central gyrus. We demonstrated specific frontal cortex GM deficits in PG without SUD comorbidities. Whereas some target regions reported in earlier studies might result from comorbid substance abuse, there seems to be a core set of frontal alterations associated with addicted gambling behaviour independent of toxic substance effects.

A biopsychological review of gambling disorder

The present review is an overview of previous experimental work on biopsychological aspects of gambling disorder. It includes the topics 1) gambling disorder from the neuroimaging and electroencephalography (EEG) perspective, 2) cognitive, executive functioning, and neuropsychological aspects of gambling disorder, and 3) rodent models of gambling disorder. Penalties and losses in gambling can differ in terms of brain activity. Also, specific patterns of brain activity, brain anatomical traits, EEG responses, and cognitive and executive performance can discriminate pathological gamblers from nonpathological gamblers. Also, pathological gamblers can display dysfunction in such brain areas as the insula, frontal lobe, and orbitofrontal cortex. Pathological gambling is a heterogeneous disorder that can vary depending on the severity of cognition, the style of gambling (strategic or not), the prospect of recovery, proneness to relapse, and proneness to treatment withdrawal. Finally, based on rodent models of gambling, the appropriateness of gambling decision is influenced by the presence of cues, the activity of dopamine receptors, and the activity of some brain areas (infralimbic, prelimbic, or rostral agranular insular cortex). Pathological gamblers differed in terms of frontoparietal brain activation compared to nonpathological gamblers (if winning or losing a game). Pathological gamblers had dysfunctional EEG activity. The severity of gambling was linked to the magnification and content of cognitive distortions. The insula was fundamental in the distortion of cognitions linked to result analysis during gambling activity.