Neural circuitry associated with risk for alcohol use disorders

Multimodal-based machine learning approach to classify features of internet gaming disorder and alcohol use disorder: A sensor-level and source-level resting-state electroencephalography activity and neuropsychological study

OBJECTIVES

Addictions have recently been classified as substance use disorder (SUD) and behavioral addiction (BA), but the concept of BA is still debatable. Therefore, it is necessary to conduct further neuroscientific research to understand the mechanisms of BA to the same extent as SUD. The present study used machine learning (ML) algorithms to investigate the neuropsychological and neurophysiological aspects of addictions in individuals with internet gaming disorder (IGD) and alcohol use disorder (AUD).

METHODS

We developed three models for distinguishing individuals with IGD from those with AUD, individuals with IGD from healthy controls (HCs), and individuals with AUD from HCs using ML algorithms, including L1-norm support vector machine, random forest, and L1-norm logistic regression (LR). Three distinct feature sets were used for model training: a unimodal-electroencephalography (EEG) feature set combined with sensor- and source-level feature; a unimodal-neuropsychological feature (NF) set included sex, age, depression, anxiety, impulsivity, and general cognitive function, and a multimodal (EEG + NF) feature set.

RESULTS

The LR model with the multimodal feature set used for the classification of IGD and AUD outperformed the other models (accuracy: 0.712). The important features selected by the model highlighted that the IGD group had differential delta and beta source connectivity between right intrahemispheric regions and distinct sensor-level EEG activities. Among the NFs, sex and age were the important features for good model performance.

CONCLUSIONS

Using ML techniques, we demonstrated the neurophysiological and neuropsychological similarities and differences between IGD (a BA) and AUD (a SUD).

Brain volumes in alcohol use disorder: Do females and males differ? A whole-brain magnetic resonance imaging mega-analysis

Emerging evidence suggests distinct neurobiological correlates of alcohol use disorder (AUD) between sexes, which however remain largely unexplored. This work from ENIGMA Addiction Working Group aimed to characterize the sex differences in gray matter (GM) and white matter (WM) correlates of AUD using a whole-brain, voxel-based, multi-tissue mega-analytic approach, thereby extending our recent surface-based region of interest findings on a nearly matching sample using a complementary methodological approach. T1-weighted magnetic resonance imaging (MRI) data from 653 people with AUD and 326 controls was analyzed using voxel-based morphometry. The effects of group, sex, group-by-sex, and substance use severity in AUD on brain volumes were assessed using General Linear Models. Individuals with AUD relative to controls had lower GM volume in striatal, thalamic, cerebellar, and widespread cortical clusters. Group-by-sex effects were found in cerebellar GM and WM volumes, which were more affected by AUD in females than males. Smaller group-by-sex effects were also found in frontotemporal WM tracts, which were more affected in AUD females, and in temporo-occipital and midcingulate GM volumes, which were more affected in AUD males. AUD females but not males showed a negative association between monthly drinks and precentral GM volume. Our results suggest that AUD is associated with both shared and distinct widespread effects on GM and WM volumes in females and males. This evidence advances our previous region of interest knowledge, supporting the usefulness of adopting an exploratory perspective and the need to include sex as a relevant moderator variable in AUD.

Changes of frontal cortical subregion volumes in alcohol dependent individuals during early abstinence: associations with treatment outcome

We previously reported that at 1-and-4 weeks of sobriety, those who relapsed after treatment demonstrated significantly smaller total frontal cortical volume than individuals who maintained abstinence for at least 12 months post treatment. The segmentation method employed did not permit examination of frontal subregions that serve as nodes of the executive, salience and emotional regulation networks; structural abnormalities in these circuits are associated with relapse in those seeking treatment for alcohol use disorders (AUD). The primary goal of this study was to determine if frontal cortical subregion volume recovery during early abstinence is associated with long-term abstinence from alcohol. We compared bilateral components of the dorsal prefrontal cortex, orbitofrontal cortex, anterior cingulate cortex and insula volumes, at 1 and 4 weeks of abstinence, between individuals who resumed drinking within 12 months of treatment (Relapsers) those who showed sustained abstinence over 12 months following treatment (Abstainers) and healthy Controls. At 1 and 4 weeks of sobriety, Relapsers demonstrated significantly smaller volumes than Controls in 15 of 20 regions of interest, while Abstainers only had smaller volumes than Controls in 5 of 20 regions. In Relapsers, increasing volumes over 1 month in multiple frontal subregions and the insula were associated with longer duration of abstinence after treatment. The persistent bilateral frontal and insula volume deficits in Relapsers over 4 weeks from last alcohol use may have implications for neurostimulation methods targeting anterior frontal/insula regions, and represent an endophenotype that differentiates those who respond more favorably to available psychosocial and pharmacological interventions.

Delay discounting and neurocognitive correlates among inner city adolescents with and without family history of substance use disorder

Adolescents with a family history (FH+) of substance use disorder (SUD) are at a greater risk for SUD, suggested to be partly due to the transmission of behavioral impulsivity. We used a delay discounting task to compare impulsivity in decision-making and its associated brain functioning among FH+ and FH - minority adolescents. Participants chose between Smaller Sooner (SS) and Larger Later (LL) rewards. The SS was available immediately (Now trials) or in the future (Not-Now trials), allowing for greater differentiation between impulsive decisions. The FH+ group showed greater impatience by responding SS more frequently than the FH - group, only on the Now trials, and even when the relative reward differences (RRD) increased. Surprisingly, there were no differences in brain activity between the groups. Combined, the groups showed greater reward activity during the Now vs. Not-Now trials in medial prefrontal/anterior cingulate, posterior cingulate, precuneus, and inferior frontal gyrus (i.e., an immediacy effect). As the RRD increased activation in the reward network decreased, including the striatum, possibly reflecting easy decision-making. These results indicate that risk for SUD, seen behaviorally among FH+ adolescents, may not yet be associated with discernable brain changes, suggesting that early intervention has the potential to reduce this risk.

Parietal P3 and midfrontal theta prospectively predict the development of adolescent alcohol use

BACKGROUND

Subclinical adolescent alcohol use is highly prevalent and may have deleterious effects on important psychosocial and brain outcomes. Prior research has focused on identifying endophenotypes of pathological drinking, and the predictors of normative drinking remain understudied. This study investigated the incremental predictive value of two potential psychophysiological endophenotypes, P3 amplitude (an index of decision making) and midfrontal theta power (a correlate of attentional control), for prospectively predicting the expression and initiation of alcohol use emerging in adolescence.

METHODS

A large (N = 594) epidemiological sample was prospectively assessed at ages 11/14/17. Alcohol/substance use was assessed at all ages via a computerized self-report inventory. EEG was recorded at age-14 during a visual oddball task to elicit P3 and theta.

RESULTS

Reduced target-related P3 and theta at age-14 prospectively predicted drinking at age-17 independent of one another. Among alcohol-naive individuals at age-14, attenuated P3 and theta increased the odds of new-onset alcohol behaviors 3 years later. Importantly, the endophenotypes provided significant incremental predictive power of future non-clinical alcohol use beyond relevant risk factors (prior alcohol use; tobacco/illicit drug initiation; parental alcohol use disorder).

CONCLUSIONS

The current report is the first of our knowledge to demonstrate that deviations in parietal P3 and midfrontal theta prospectively predict the emergence of normative/non-pathological drinking. P3 and theta provide modest yet significant explanatory variance beyond prominent self-report and familial risk measures. Findings offer strong evidence supporting the predictive utility of P3 and theta as candidate endophenotypes for adolescent drinking.

Cigarette smoking history is associated with poorer recovery in multiple neurocognitive domains following treatment for an alcohol use disorder

Cigarette smoking is associated with neurocognitive dysfunction in various populations, including those seeking treatment for an alcohol use disorder (AUD). This study compared the rate and extent of recovery on measures of processing speed, executive functions, general intelligence, visuospatial skills and working memory in treatment-seeking alcohol dependent individuals (ALC) who were never-smokers (nvsALC), former-smoker (fsALC), and active smokers (asALC), over approximately 8 months of abstinence from alcohol. Methods: ALC participants were evaluated at approximately 1 month of abstinence (AP1; n = 132) and reassessed after 8 months of sobriety (AP2; n = 54). Never-smoking controls (CON; n = 33) completed a baseline and follow-up (n = 19) assessment approximately 9 months later. Domains evaluated were executive functions, general intelligence, processing speed, visuospatial skills and working memory; a domain composite was formed from the arithmetic average of the foregoing domains. nvsALC showed greater improvement than fsALC, asALC and CON on most domains over the AP1-AP2 interval. fsALC demonstrated greater recovery than asALC on all domains except visuospatial skills; fsALC also showed greater improvements than CON on general intelligence, working memory and domain composite. asALC did not show significant improvement on any domain over the AP1-AP2 interval. At 8 months of abstinence, asALC were inferior to CON and nvsALC on multiple domains, fsALC performed worse than nvsALC on several domains, but nvsALC were not different from CON on any domain. Our results provide robust evidence that smoking status influenced the rate and extent of neurocognitive recovery between 1 and 8 months of abstinence in this ALC cohort. Chronic smoking in AUD likely contributes to the considerable heterogeneity observed in neurocognitive recovery during extended abstinence. The findings provide additional strong support for the benefits of smoking cessation and the increasing clinical movement to offer smoking cessation resources concurrent with treatment for AUD.

Association Between Age and Familial Risk for Alcoholism on Functional Connectivity in Adolescence

OBJECTIVE

Youth with a family history of alcohol use disorder (family history positive [FHP]) are at increased risk for developing maladaptive substance use relative to family history negative (FHN) peers. Building on earlier studies demonstrating morphological differences and distinct patterns of neural activation in FHP, the purpose of the present study was to investigate differential intrinsic functional connectivity among brain networks indexing premorbid risk of developing alcohol use disorder (AUD).

METHOD

The current study examined intrinsic functional connectivity using resting state functional magnetic resonance imaging in 191 adolescents 13 to 18 years of age with and without family history of AUD via independent component analysis, a method enabling data-driven investigation of internetwork and intranetwork connectivity among brain regions at rest.

RESULTS

Analyses revealed significantly lower intranetwork connectivity in FHP compared to FHN participants between the dorsal premotor cortex and other sensorimotor network regions. Reduced intranetwork connectivity in this region was further correlated with the number of biological family members with AUD and mood disorders. Robust differences were also evident in internetwork connectivity as a function of age. However, there was no evidence for family history by age interactions.

CONCLUSION

Intra- but not internetwork connectivity appears to differentiate FHP and FHN adolescents, whereas age differences within adolescence are marked by differences in internetwork connectivity.

P3 Component as a Potential Endophenotype for Control Inhibition in Offspring of Alcoholics

Aims

To assess inhibitory processes and the ongoing event-related potential (ERP) activity of offspring of alcoholics (OA) during a Go/No-Go task, with the purpose of characterizing possible psychophysiological endophenotypes for alcohol-dependent vulnerability.

Short summary

EEG recordings and ERP measurements of young adults with positive and negative family history of alcoholism where obtained while they performed a Go/No-Go task to assess inhibitory processes. Offspring of alcoholics showed a different ERP pattern compared to the control group and exerted greater effort than the control group.

Methods

ERP measurements were obtained by electroencephalogram (EEG) recordings of 65 participants divided into two groups: one group of 30 subjects with positive family history of alcoholism and a control group of 35 subjects with negative family history of alcoholism. They performed a Go/No-Go task, where each individual was required to classify visual stimuli by colour (Go) and inhibit their response to a No-Go signal.

Results

OA have higher P3 amplitudes during the Go condition in all of the regions analysed and higher No-Go P3 amplitudes than control subjects in the frontal region. Unlike controls, OA have no differences between the P3 amplitudes across conditions.

Conclusions

The absence of differences between the P3 Go and No-Go observed in the OA group can be interpreted as a possible alteration related with inhibition, in a way that they may need to recruit similar resources for inhibitory and classificational processes for both conditions. Therefore, the P3 component may be considered as a useful endophenotype and a vulnerability marker to develop addictive behaviour.

Neurophysiological Correlates and Differential Drug Response in Subjects With a Family History of an Alcohol Use Disorder

A family history of an alcohol use disorder (AUD) has been shown to increase one's risk of developing an AUD. Additionally, a positive family history of AUD (family history positive (FHP)) has neurobiological and neuropsychopharmacological consequences, and this review summarizes differential drug response as well as neuroanatomical and neurocognitive correlates. FHP status is related to altered responses to a number of drugs, including substances with abuse liability like alcohol, opioids, amphetamines, and ketamine. FHP individuals demonstrate fewer aversive effects and more rewarding response to both alcohol and subanesthetic dose ketamine. Ketamine is a rapid-acting antidepressant, and several studies have reported that ketamine is more effective for FHP treatment-resistant depressed individuals. In short, the reviewed neurophysiological differences may contribute to ketamine's enhanced antidepressant efficacy in FHP patients. Volumetric differences in the amygdala, nucleus accumbens, neocortex, and cerebellum are commonly reported. Furthermore, FHP has also been associated with altered neurocognitive performance, e.g., increased impulsivity. The imaging and psychological literature supports a neurodevelopmental lag hypothesis in FHP youth. The review will further discuss these findings in depth.

Limitations of lymphoblastoid cell lines for functional analysis of SNPs

OBJECTIVE

Single nucleotide polymorphisms (SNPs) are widely linked to the susceptibility and penetrance of diseases. SNP rs886205 (A/G) located in the aldehyde dehydrogenase 2 (ALDH2) promoter is associated with esophageal carcinoma in alcohol-dependent patients. Previously, we found an interaction of the SNP with the methylation of promoter regions as well as the protein levels of ALDH2 in alcohol-dependent patients. To study the DNA-protein interactions involved in rs886205 mediated regulation of ALDH2, we chose lymphoblastoid cell lines harboring AA/GA/GG genotype and acquired two for each genotype from National Human Genome Research Institute repository. We measured the promoter methylation of ALDH2 by using bisulfite sequencing and quantified protein expression of ALDH2 by western blot to compare the cell lines with the previous findings in patients.

RESULTS

DNA methylation showed significant differences not only based on genotype but also due to the different background of the cells owing to their origin from different individuals. Although ALDH2 protein expression seemed to be driven by the rs886205 genotype, results were not in consensus with data from the patient cohorts. Our findings show the limitations of the usage of lymphoblastoid cell lines due to the unavoidable background genetic differences that may influence the effect of SNP.

Facial emotion recognition in schizophrenia: An exploratory study on the role of comorbid alcohol and substance use disorders and COMT Val158Met

OBJECTIVES

To explore whether facial emotion recognition (FER), impaired in both schizophrenia and alcohol and substance use disorders (AUDs/SUDs), is additionally compromised among comorbid subjects, also considering the role of catechol-O-methyltransferase (COMT) Val158Met.

METHODS

We conducted a cross-sectional study, randomly recruiting 67 subjects with a DSM-IV-TR diagnosis of schizophrenia, and rigorously assessing AUDs/SUDs and COMT Val158Met polymorphism. FER was assessed using the Ekman 60 Faces Test- EK-60F.

RESULTS

As a whole, the sample scored significantly lower than normative data on EK-60F. However, subjects with comorbid AUDs/SUDs did not perform worse on EK-60F than those without, who had a better performance on EK-60F if they carried the COMT Val/Met variant.

CONCLUSIONS

This study is the first to date examining the impact of AUDs/SUDs and COMT variants on FER in an epidemiologically representative sample of subjects with schizophrenia. Our findings do not suggest an additional impairment from comorbid AUDs/SUDs on FER among subjects with schizophrenia, whilst COMT Val158Met, though based on a limited sample, might have a role just among those without AUDs/SUDs. Based on our results, additional research is needed also exploring differential roles of various substances.

Nucleus accumbens functional connectivity at age 20 is associated with trajectory of adolescent cannabis use and predicts psychosocial functioning in young adulthood

AIMS

(1) To identify trajectories of cannabis use across adolescence, (2) to measure the influence of cannabis use characteristics on functional connectivity of the nucleus accumbens (NAcc) and (3) to assess whether patterns of functional connectivity related to cannabis use are associated with psychosocial functioning 2 years later.

DESIGN

The Pitt Mother and Child Project (PMCP) is a prospective, longitudinal study of male youth at high risk for psychopathology based on family income and gender.

SETTING

Participants were recruited between age 6 and 17 months from the Women, Infants and Children Nutritional Supplement program (WIC) in the Pittsburgh, Pennsylvania area.

PARTICIPANTS

A total of 158 PMCP young men contributed functional magnetic resonance imaging (fMRI) and substance use data at age 20 years.

MEASUREMENTS

Latent class growth analysis was used to determine trajectories of cannabis use frequency from age 14 to 19 years. Psychophysiological interaction (PPI) analysis was used to measure functional connectivity between the NAcc and prefrontal cortex (PFC). Adolescent cannabis use trajectory, recent frequency of use and age of initiation were considered as developmental factors. We also tested whether functional connectivity was associated with depressive symptoms, anhedonia and educational attainment at age 22.

FINDINGS

We identified three distinct trajectories of adolescent cannabis use, characterized by stable high, escalating or stable low use. The cannabis use trajectory group had a significant effect on NAcc functional connectivity to the medial PFC (F = 11.32, Z = 4.04, P_{family-wise error-corrected (FWE-corr)}  = 0.000). The escalating trajectory group displayed a pattern of negative NAcc-mPFC connectivity that was linked to higher levels of depressive symptoms (r = -0.17, P < .05), anhedonia (r = -0.19, P < .05) and lower educational attainment (t = -2.77, P < .01) at age 22.

CONCLUSIONS

Pattern of cannabis use frequency across adolescence in US youth could have consequences for mood symptoms and educational attainment in early adulthood via altered function in neural reward circuitry.

Volumetric Differences in Cerebellar Lobes in Individuals from Multiplex Alcohol Dependence Families and Controls: Their Relationship to Externalizing and Internalizing Disorders and Working Memory

Offspring from families with multiple cases of alcohol dependence have a greater likelihood of developing alcohol dependence and related substance use disorders. Greater susceptibility for these disorders may be related to cerebellar morphology. Because posterior regions of the cerebellum are associated with cognitive abilities, we investigated whether high-risk offspring would display regionally specific differences in cerebellar morphology and whether these would be related to working memory performance. The relationship to externalizing and internalizing psychopathology was of interest because cerebellar morphology has previously been associated with a cognitive affective syndrome. A total of 131 participants underwent magnetic resonance imaging (MRI) with volumes of the cerebellar lobes obtained with manual tracing. These individuals were from high-risk (HR) for alcohol dependence families (N = 72) or from low-risk (LR) control families (N = 59). All were enrolled in a longitudinal follow-up that included repeated clinical assessments during childhood and young-adulthood prior to the scan that provided information on Axis I psychopathology. The Working Memory Index of the Wechsler Memory Scale was given at the time of the scan. Larger volumes of the corpus medullare and inferior posterior lobes and poorer working memory performance were found for the HR offspring relative to LR controls. Across all subjects, a significant positive association between working memory and total volume of corpus of the cerebellum was seen, controlling for familial risk. Presence of an internalizing or externalizing disorder interacting with familial risk was also associated with volume of the corpus medullare.

Regional brain volume changes in alcohol-dependent individuals during early abstinence: associations with relapse following treatment

Cross-sectional structural magnetic resonance (MR) imaging studies of individuals with an alcohol use disorder (AUD) report that those who relapse after treatment, relative to individuals who maintain a period of extended abstinence, show greater morphological abnormalities in multiple brain regions near the inception of treatment, particularly in the frontal lobe. However, given the cross-sectional design of previous studies, it is unclear if the baseline morphological differences between future abstainers and relapsers were maintained over the course of early recovery. The primary goal of this study was to determine if frontal lobe tissue volume recovery during early abstinence is associated with long-term abstinence from alcohol. We compared frontal, parietal, temporal and occipital grey matter (GM) and white matter (WM) volumes, at 1 and 4 weeks of abstinence, among individuals who resumed alcohol consumption within 12 months of treatment (Relapsers) and those who showed sustained abstinence over 12 months following treatment (Abstainers). At 1 and 4 weeks of sobriety, both Abstainers and Relapsers demonstrated significantly smaller GM volumes than Controls in the majority of ROIs, but Relapsers exhibited significantly smaller bilateral frontal GM volumes than Abstainers. No significant group differences were observed for any WM region of interest. The persistent bilateral frontal GM volume deficits in Relapsers over 4 weeks from last alcohol use may represent an endophenotype that differentiates those who respond more favorably to the typical psychosocial and pharmacological interventions provided for AUD.

A KCNJ6 gene polymorphism modulates theta oscillations during reward processing

Event related oscillations (EROs) are heritable measures of neurocognitive function that have served as useful phenotype in genetic research. A recent family genome-wide association study (GWAS) by the Collaborative Study on the Genetics of Alcoholism (COGA) found that theta EROs during visual target detection were associated at genome-wide levels with several single nucleotide polymorphisms (SNPs), including a synonymous SNP, rs702859, in the KCNJ6 gene that encodes GIRK2, a G-protein inward rectifying potassium channel that regulates excitability of neuronal networks. The present study examined the effect of the KCNJ6 SNP (rs702859), previously associated with theta ERO to targets in a visual oddball task, on theta EROs during reward processing in a monetary gambling task. The participants were 1601 adolescent and young adult offspring within the age-range of 17-25years (800 males and 801 females) from high-dense alcoholism families as well as control families of the COGA prospective study. Theta ERO power (3.5-7.5Hz, 200-500ms post-stimulus) was compared across genotype groups. ERO theta power at central and parietal regions increased as a function of the minor allele (A) dose in the genotype (AA>AG>GG) in both loss and gain conditions. These findings indicate that variations in the KCNJ6 SNP influence magnitude of theta oscillations at posterior loci during the evaluation of loss and gain, reflecting a genetic influence on neuronal circuits involved in reward-processing. Increased theta power as a function of minor allele dose suggests more efficient cognitive processing in those carrying the minor allele of the KCNJ6 SNPs. Future studies are needed to determine the implications of these genetic effects on posterior theta EROs as possible "protective" factors, or as indices of delays in brain maturation (i.e., lack of frontalization).

Imaging the Addicted Brain: Alcohol

Alcohol use disorder (AUD) represents a major public health issue due to its prevalence and severe health consequences. It may affect several aspects of an individual's life including work and relationships, and it also increases risk for additional problems such as brain injury. The causes and outcomes of AUD are varied; thus, attempting to understand this complex phenomenon requires investigation from multiple perspectives. Magnetic resonance imaging (MRI) is a powerful means to investigate brain anatomical and functional alterations related to AUD. Recent advances in MRI methods allow better investigation of the alterations to structural and functional brain networks in AUD. Here, we focus on findings from studies using multiple MRI techniques, which converge to support the considerable vulnerability of frontal systems. Indeed, MRI studies provide evidence for a "disconnection syndrome" which could be involved in the poor behavioral control observed in AUD.

Serial longitudinal magnetic resonance imaging data indicate non-linear regional gray matter volume recovery in abstinent alcohol-dependent individuals

The trajectory of regional volume changes during the first year of sustained abstinence in those recovering from an alcohol use disorder is unclear because previous research typically employed only two assessment points. To better understand the trajectory of regional brain volume recovery in treatment-seeking alcohol-dependent individuals (ALC), regional brain volumes were measured after 1 week, 1 month and 7.5 months of sustained abstinence via magnetic resonance imaging at 1.5 T. ALC showed significant volume increases in frontal, parietal and occipital gray matter (GM) and white matter (WM), total cortical GM and total lobar WM, thalamus and cerebellum, and decreased ventricular volume over 7.5 months of abstinence. Volume increases in regional GM were significantly greater over 1 week to 1 month than from 1 month to 7.5 months of abstinence, indicating a non-linear rate of change in regional GM over 7.5 months. Overall, regional lobar WM showed linear volume increases over 7.5 months. With increasing age, smoking ALC showed lower frontal and total cortical GM volume recovery than non-smoking ALC. Despite significant volume increases, ALC showed smaller GM volumes in all regions, except the frontal cortex, than controls after 7.5 months of abstinence. ALC and controls showed no regional WM volume differences at any assessment point. In non-smoking ALC only, increasing regional GM and WM volumes were related to improving processing speed. Findings may indicate a differential rate of recovery of cell types/cellular components contributing to GM and WM volume during early abstinence, and that GM volume deficits persist after 7.5 months of sustained sobriety in this ALC cohort.

Adolescents' Neural Processing of Risky Decisions: Effects of Sex and Behavioral Disinhibition

Background

Accidental injury and homicide, relatively common among adolescents, often follow risky behaviors; those are done more by boys and by adolescents with greater behavioral disinhibition (BD).

Hypothesis

Neural processing during adolescents' risky decision-making will differ in youths with greater BD severity, and in males vs. females, both before cautious behaviors and before risky behaviors.

Methodology/Principal Findings

81 adolescents (Patients with substance and conduct problems, and comparison youths (Comparisons)), assessed in a 2 x 2 design (Patients:Comparisons x Male:Female) repeatedly decided between doing a cautious behavior that earned 1 cent, or a risky one that either won 5 or lost 10 cents. Odds of winning after risky responses gradually decreased. Functional magnetic resonance imaging captured brain activity during 4-sec deliberation periods preceding responses. Most neural activation appeared in known decision-making structures. Patients, who had more severe BD scores and clinical problems than Comparisons, also had extensive neural hypoactivity. Comparisons' greater activation before cautious responses included frontal pole, medial prefrontal cortex, striatum, and other regions; and before risky responses, insula, temporal, and parietal regions. Males made more risky and fewer cautious responses than females, but before cautious responses males activated numerous regions more than females. Before risky behaviors female-greater activation was more posterior, and male-greater more anterior.

Conclusions/Significance

Neural processing differences during risky-cautious decision-making may underlie group differences in adolescents' substance-related and antisocial risk-taking. Patients reported harmful real-life decisions and showed extensive neural hypoactivity during risky-or-cautious decision-making. Males made more risky responses than females; apparently biased toward risky decisions, males (compared with females) utilized many more neural resources to make and maintain cautious decisions, indicating an important risk-related brain sexual dimorphism. The results suggest new possibilities for prevention and management of excessive, dangerous adolescent risk-taking.

Psychological and Neurobiological Precursors of Alcohol Use Disorders in High Risk Youth

It has long been known that Alcohol Use Disorders (AUDs) run in families with substantial heritability. Determining the specific genetic underpinnings of these disorders has been challenging because of the clinical heterogeneity and variable expression across the lifespan. The search for endophenotypic biological variation associated with the AUD and related substance use disorder (SUD) phenotypes is based on the belief that an endophenotype is more proximal to the causative gene. Identification of genes conferring increased susceptibility has important implications for treatment through the potential development of medications that target specific genetic pathways. High risk family designs that contrast offspring with and without a familial/genetic background have provided valuable insights into the psychological characteristics (executive control, affective regulation, decision making and social cognition) that differentiate such individuals. The current chapter will review these with a focus on brain morphology of specific regions, the coordinated activity of neural networks, and developmental trajectories of electrophysiological activity.

Brain activity classifies adolescents with and without a familial history of substance use disorders

We aimed to uncover differences in brain circuits of adolescents with parental positive or negative histories of substance use disorders (SUD), when performing a task that elicits emotional conflict, testing whether the brain circuits could serve as endophenotype markers to distinguish these adolescents. We acquired functional magnetic resonance imaging data from 11 adolescents with a positive familial history of SUD (FH+ group) and seven adolescents with a negative familial history of SUD (FH− group) when performing an emotional stroop task. We extracted brain features from the conflict-related contrast images in group level analyses and granger causality indices (GCIs) that measure the causal interactions among regions. Support vector machine (SVM) was applied to classify the FH+ and FH− adolescents. Adolescents with FH+ showed greater activity and weaker connectivity related to emotional conflict, decision making and reward system including anterior cingulate cortex (ACC), prefrontal cortex (PFC), and ventral tegmental area (VTA). High classification accuracies were achieved with leave-one-out cross validation (89.75% for the maximum conflict, 96.71% when combining maximum conflict and general conflict contrast, 97.28% when combining activity of the two contrasts and GCIs). Individual contributions of the brain features to the classification were further investigated, indicating that activation in PFC, ACC, VTA and effective connectivity from PFC to ACC play the most important roles. We concluded that fundamental differences of neural substrates underlying cognitive behaviors of adolescents with parental positive or negative histories of SUD provide new insight into potential neurobiological mechanisms contributing to the elevated risk of FH+ individuals for developing SUD.

Shared genetic factors influence amygdala volumes and risk for alcoholism

Alcohol abuse and dependence (alcohol use disorders, AUDs) are associated with brain shrinkage. Subcortical structures including the amygdala, hippocampus, ventral striatum, dorsal striatum, and thalamus subserve reward functioning and may be particularly vulnerable to alcohol-related damage. These structures may also show pre-existing deficits impacting the development and maintenance of AUD. It remains unclear whether there are common genetic features underlying both subcortical volumes and AUD. In this study, structural brain images were acquired from 872 Mexican-American individuals from extended pedigrees. Subcortical volumes were obtained using FreeSurfer, and quantitative genetic analyses were performed in SOLAR. We hypothesized the following: (1) reduced subcortical volumes in individuals with lifetime AUD relative to unrelated controls; (2) reduced subcortical volumes in individuals with current relative to past AUD; (3) in non-AUD individuals, reduced subcortical volumes in those with a family history of AUD compared to those without; and (4) evidence for common genetic underpinnings (pleiotropy) between AUD risk and subcortical volumes. Results showed that individuals with lifetime AUD showed larger ventricular and smaller amygdala volumes compared to non-AUD individuals. For the amygdala, there were no differences in volume between current vs past AUD, and non-AUD individuals with a family history of AUD demonstrated reductions compared to those with no such family history. Finally, amygdala volume was genetically correlated with the risk for AUD. Together, these results suggest that reduced amygdala volume reflects a pre-existing difference rather than alcohol-induced neurotoxic damage. Our genetic correlation analysis provides evidence for a common genetic factor underlying both reduced amygdala volumes and AUD risk.

Blunted Heart Rate Response as a Potential Endophenotype of Substance Use Disorders: Evidence from High-Risk Youth

BACKGROUND

Children of parents with a substance use disorder (CPSUD) are at increased risk for developing problematic substance use later in life. Endophenotypes may help to clarify the mechanism behind this increased risk. However, substance use and externalizing symptoms may confound the relation between dysregulated physiological stress responding and familial risk for substance use disorders (SUDs).

METHODS

We examined whether heart rate (HR) responses differed between CPSUDs and controls. Participants (aged 11-20 years) were CPSUDs (N = 75) and controls (N = 363), semi-matched on the basis of sex, socioeconomic status, and ethnicity. HR was measured continuously during a psychosocial stress procedure. Substance use and externalizing symptoms were self-reported and mother-reported, respectively.

RESULTS

A piecewise, mixed-effects model was fit for HR across the stress procedure, with fixed effects for HR reactivity and HR recovery. CPSUDs showed a blunted HR recovery. CPSUDs reported drinking more frequently, were more likely to use tobacco daily, were more likely to report ever use of cannabis and used cannabis more frequently, and exhibited more externalizing symptoms. These variables did not confound the relation between familial risk for SUDs and a blunted HR recovery.

CONCLUSION

Our findings suggest dysregulated autonomic nervous system (ANS) responding in CPSUDs and contribute to the accumulating evidence for ANS dysregulation as a potential endophenotype for SUDs.

Amygdala Volume in Offspring from Multiplex for Alcohol Dependence Families: The Moderating Influence of Childhood Environment and 5-HTTLPR Variation

BACKGROUND

The increased susceptibility for developing alcohol dependence seen in offspring from families with alcohol dependence may be related to structural and functional differences in brain circuits that influence emotional processing. Early childhood environment, genetic variation in the serotonin transporter-linked polymorphic region (5-HTTLPR) of the SLCA4 gene and allelic variation in the Brain Derived Neurotrophic Factor (BDNF) gene have each been reported to be related to volumetric differences in the temporal lobe especially the amygdala.

METHODS

Magnetic resonance imaging was used to obtain amygdala volumes for 129 adolescent/young adult individuals who were either High-Risk (HR) offspring from families with multiple cases of alcohol dependence (N=71) or Low-Risk (LR) controls (N=58). Childhood family environment was measured prospectively using age-appropriate versions of the Family Environment Scale during a longitudinal follow-up study. The subjects were genotyped for Brain-Derived Neurotrophic Factor (BDNF) Val66Met and the serotonin transporter polymorphism (5-HTTLPR). Two family environment scale scores (Cohesion and Conflict), genotypic variation, and their interaction were tested for their association with amygdala volumes. Personal and prenatal exposure to alcohol and drugs were considered in statistical analyses in order to more accurately determine the effects of familial risk group differences.

RESULTS

Amygdala volume was reduced in offspring from families with multiple alcohol dependent members in comparison to offspring from control families. High-Risk offspring who were carriers of the S variant of the 5-HTTLPR polymorphism had reduced amygdala volume in comparison to those with an LL genotype. Larger amygdala volume was associated with greater family cohesion but only in Low-Risk control offspring.

CONCLUSIONS

Familial risk for alcohol dependence is an important predictor of amygdala volume even when removing cases with significant personal exposure and covarying for prenatal exposure effects. The present study provides new evidence that amygdala volume is modified by 5-HTTLPR variation in High-Risk families.

Effects of cigarette smoking history on neurocognitive recovery over 8 months of abstinence in alcohol-dependent individuals

BACKGROUND

This study compared the rate and extent of recovery on measures of learning and memory, processing speed, and working memory in treatment-seeking alcohol-dependent individuals (ALC) who were never smokers (nvsALC), former smokers (fsALC), and active smokers (asALC) over the first 8 months of sustained abstinence from alcohol. Assessments after 1 week, 1 month, and 8 months of abstinence in ALC enabled a comparison of the rates of neurocognitive changes from 1 week to 1 month versus 1 to 8 months of abstinence.

METHODS

ALC and never-smoking controls were administered standardized measures of auditory-verbal and visuospatial learning and memory, processing speed, and working memory. Controls completed a baseline assessment and a follow-up approximately 9 months later.

RESULTS

Over 8 months of abstinence, asALC showed poorer recovery than nvsALC on visuospatial learning, and both fsALC and asALC recovered less than nvsALC on processing speed measures. The corresponding recovery rates for the ALC group, as a whole, were greater from 1 week to 1 month than from 1 to 8 months of abstinence; these findings were largely driven by improvements in nvsALC. The recovery levels for fsALC on most measures were similar to those in asALC. Additionally, over 8 months, asALC showed significantly less improvement with increasing age than nvsALC on measures of processing speed and learning and memory. At 8 months of abstinence, asALC were inferior to controls and nvsALC on multiple measures, fsALC performed worse than nvsALC on several tests, but nvsALC were not different from controls on any measure.

CONCLUSIONS

Overall, ALC showed rapid improvement on measures of visuospatial learning and processing speed during the first month of abstinence from alcohol. Results also provide robust evidence that smoking status influenced the rate and level of neurocognitive recovery over 8 months of abstinence in this ALC cohort.

Maladaptive decision making and substance use outcomes in high-risk individuals: preliminary evidence for the role of 5-HTTLPR variation

OBJECTIVE

Individuals with multiple alcohol-dependent (AD) relatives are at increased risk for substance use disorders (SUDs). Prospective, longitudinal studies of high-risk (HR) individuals afford the opportunity to determine potential risk markers of SUDs. The current study assessed the effect of familial risk and genetic variation on Iowa Gambling Task (IGT) performance and tested for an association between IGT performance and SUD outcomes.

METHOD

Individuals from multiplex AD families (n = 63) and low-risk (LR; n = 45) control families, ages 16-34 years, were tested using a computerized version of the IGT. SUD outcomes were assessed at approximately yearly intervals. 5-HTTLPR and COMT genotypes were available for the majority of participants (n = 86).

RESULTS

HR offspring showed poorer performance overall on the IGT and especially poor performance on the final trial block (Block 5), indicating a failure to improve decision making with previous experience. The 5-HTTLPR short-allele homozygote participants performed worse than long-allele carriers, with HR S/S carriers exhibiting particularly poor performance. There was no main effect of COMT on IGT performance and no significant COMT by Risk interaction. Significantly more individuals in the HR than LR group met criteria for SUD. Importantly, disadvantageous performance on IGT Block 5 was significantly associated with an earlier age at SUD onset.

CONCLUSIONS

This is the first study to show that both familial risk of SUD and 5-HTTLPR variation impact performance on the IGT. Poorer IGT performance was associated with earlier onset of SUD, suggesting that HR individuals who fail to appropriately attend to long-term costs and benefits during a decision-making task are especially at risk for developing SUD in adolescence and young adulthood.

The cerebellum and addiction: insights gained from neuroimaging research

Although cerebellar alterations have been consistently noted in the addiction literature, the pathophysiology of this link remains unclear. The cerebellum is commonly classified as a motor structure, but human functional neuroimaging along with clinical observations in cerebellar stroke patients and anatomical tract tracing in non-human primates suggests its involvement in cognitive and affective processing. A comprehensive literature search on the role of the cerebellum in addiction was performed. This review article (1) considers the potential role of the cerebellum in addiction; (2) summarizes the cerebellar structural alterations linked to addiction; (3) presents the functional neuroimaging evidence linking the cerebellum with addiction; and (4) proposes a model for addiction that underscores the role of the cerebellum. The data implicate the cerebellum as an intermediary between motor and reward, motivation and cognitive control systems, as all are relevant etiologic factors in addiction. Furthermore, consideration of these findings could contribute to deeper and more sophisticated insights into normal reward and motivational function. The goal of this review is to spread awareness of cerebellar involvement in addictive processes, and to suggest a preliminary model for its potential role.

Volumetric differences in the anterior cingulate cortex prospectively predict alcohol-related problems in adolescence

RATIONALE

Individual differences in brain structure and function are suggested to exist prior to the onset of alcohol abuse. Cross-sectional studies have demonstrated abnormalities in brain regions underlying affective processes that may form a pathway to the emergence of later alcohol abuse and dependence in vulnerable individuals. However, no prospective studies have examined whether these abnormalities predict later problems with alcohol.

OBJECTIVE

This study aims to examine whether individual differences in affect and brain volume prospectively predict alcohol-related problems in adolescence.

METHOD

Adolescent drinkers (n = 98) were recruited from an ongoing prospective, longitudinal study examining adolescent emotional development. At age 12, participants underwent structural magnetic resonance imaging to obtain volumetric data on the amygdala, hippocampus, orbitofrontal cortex, and anterior cingulate cortex (ACC), and completed a self-report measure of affective temperament. At age 16, participants completed a questionnaire measuring alcohol use, with 39 % reporting alcohol-related problems in the past year.

RESULTS

Pre-existing differences in the left ACC predicted problem drinking. Alcohol-related problems were associated with higher levels of temperamental negative affectivity; however, these were not correlated with anterior cingulate volumes.

CONCLUSIONS

These findings indicate that individual differences in the structural morphology of the anterior cingulate, a region implicated in affective processes, self-control, and drug addiction, predict later alcohol-related problems. Although this finding remained significant after controlling for other substance use and psychopathology, future research is required to test its specificity for alcohol use disorders.

Relationships between reward sensitivity, risk-taking and family history of alcoholism during an interactive competitive fMRI task

Background

Individuals with a positive family history for alcoholism (FHP) have shown differences from family-history-negative (FHN) individuals in the neural correlates of reward processing. FHP, compared to FHN individuals, demonstrate relatively diminished ventral striatal activation during anticipation of monetary rewards, and the degree of ventral striatal activation shows an inverse correlation with specific impulsivity measures in alcohol-dependent individuals. Rewards in socially interactive contexts relate importantly to addictive propensities, yet have not been examined with respect to how their neural underpinnings relate to impulsivity-related measures. Here we describe impulsivity measures in FHN and FHP individuals as they relate to a socially interactive functional magnetic resonance imaging (fMRI) task.

Methods

Forty FHP and 29 FHN subjects without histories of Axis-I disorders completed a socially interactive Domino task during functional magnetic resonance imaging and completed self-report and behavioral impulsivity-related assessments.

Results

FHP compared to FHN individuals showed higher scores (p = .004) on one impulsivity-related factor relating to both compulsivity (Padua Inventory) and reward/punishment sensitivity (Sensitivity to Punishment/Sensitivity to Reward Questionnaire). Multiple regression analysis within a reward-related network revealed a correlation between risk-taking (involving another impulsivity-related factor, the Balloon Analog Risk Task (BART)) and right ventral striatum activation under reward >punishment contrast (p<0.05 FWE corrected) in the social task.

Conclusions

Behavioral risk-taking scores may be more closely associated with neural correlates of reward responsiveness in socially interactive contexts than are FH status or impulsivity-related self-report measures. These findings suggest that risk-taking assessments be examined further in socially interactive settings relevant to addictive behaviors.

Brain proton magnetic resonance spectroscopy of alcohol use disorders

This chapter critically reviews brain proton magnetic resonance spectroscopy ((1)H MRS) studies performed since 1994 in individuals with alcohol use disorders (AUD). We describe the neurochemicals that can be measured in vivo at the most common magnetic field strengths, summarize our knowledge about their general brain functions, and briefly explain some basic human (1)H MRS methods. Both cross-sectional and longitudinal research of individuals in treatment and of treatment-naïve individuals with AUD are discussed and interpreted on the basis of reported neuropathology. As AUDs are highly comorbid with chronic cigarette smoking and illicit substance abuse, we also summarize reports on their respective influences on regional proton metabolite levels. After reviewing research on neurobiologic correlates of relapse and genetic influences on brain metabolite levels, we finish with suggestions on future directions for (1)H MRS studies in AUDs. The review demonstrates that brain metabolic alterations associated with AUDs as well as their cognitive correlates are not simply a consequence of chronic alcohol consumption. Future MR research of AUDs in general has to be better prepared - and supported - to study clinically complex relationships between personality characteristics, comorbidities, neurogenetics, lifestyle, and living environment, as all these factors critically affect an individual's neurometabolic profile. (1)H MRS is uniquely positioned to tackle these complexities by contributing to a comprehensive biopsychosocial profile of individuals with AUD: it can provide non-invasive biochemical information on select regions of the brain at comparatively low overall cost for the ultimate purpose of informing more efficient treatments of AUDs.

Interactive effects of chronic cigarette smoking and age on brain volumes in controls and alcohol-dependent individuals in early abstinence

Chronic alcohol-use disorders (AUDs) have been shown to interact with normal age-related volume loss to exacerbate brain atrophy with increasing age. However, chronic cigarette smoking, a highly co-morbid condition in AUD and its influence on age-related brain atrophy have not been evaluated. We performed 1.5 T quantitative magnetic resonance imaging in non-smoking controls [non-smoking light drinking controls (nsCONs); n = 54], smoking light drinking controls (sCONs, n = 34), and one-week abstinent, treatment-seeking alcohol-dependent (ALC) non-smokers (nsALCs, n = 35) and smokers (sALCs, n = 43), to evaluate the independent and interactive effects of alcohol dependence and chronic smoking on regional cortical and subcortical brain volumes, emphasizing the brain reward/executive oversight system (BREOS). The nsCONs and sALCs showed greater age-related volume losses than the nsALCs in the dorsal prefrontal cortex (DPFC), total cortical BREOS, superior parietal lobule and putamen. The nsALCs and sALCs demonstrated smaller volumes than the nsCONs in most cortical region of interests (ROIs). The sCONs had smaller volumes than the nsCONs in the DPFC, insula, inferior parietal lobule, temporal pole/parahippocampal region and all global cortical measures. The nsALCs and sALCs had smaller volumes than the sCONs in the DPFC, superior temporal gyrus, inferior and superior parietal lobules, precuneus and all global cortical measures. Volume differences between the nsALCs and sALCs were observed only in the putamen. Alcohol consumption measures were not related to volumes in any ROI for ALC; smoking severity measures were related to corpus callosum volume in the sCONs and sALCs. The findings indicate that consideration of smoking status is necessary for a better understanding of the factors contributing to regional brain atrophy in AUD.

Neural correlates of impulsivity in healthy males and females with family histories of alcoholism

Individuals family-history positive (FHP) for alcoholism have increased risk for the disorder, which may be mediated by intermediate behavioral traits such as impulsivity. Given the sex differences in the risk for and clinical presentation of addictive disorders, risk for addiction may be differentially mediated by impulsivity within FHP males and females. FHP (N=28) and family-history negative (FHN, N=31) healthy, non-substance-abusing adults completed an fMRI Go/No-Go task and were assessed on impulsivity and alcohol use. Effects of family history and sex were investigated as were associations between neural correlates of impulse control and out-of-scanner measures of impulsivity and alcohol use. FHP individuals showed greater activation in the left anterior insula and inferior frontal gyrus during successful inhibitions, an effect that was driven primarily by FHP males. Higher self-reported impulsivity and behavioral discounting impulsivity, but not alcohol use measures, were associated with greater BOLD signal in the region that differentiated the FHP and FHN groups. Impulsivity factors were associated with alcohol use measures across the FHP and FHN groups. These findings are consistent with increased risk for addiction among FHP individuals being conferred through disrupted function within neural systems important for impulse control.

Family history of alcohol dependence modulates functional neurophysiology in mood/anxiety disorders

BACKGROUND

A family history (FH) of alcohol dependence (AD) not only increases the risk for AD, but is also associated with an increased risk for mood and anxiety disorders. However, it is unknown how a FH of AD affects neural substrates in patients with mood and anxiety disorders. In this study we examined the effects of an alcoholic FH on cognitive and emotional functions in these patients using functional magnetic resonance imaging (fMRI). Method In a sample of non-alcoholic patients with depressive and/or anxiety disorders from the Netherlands Study of Depression and Anxiety (NESDA) neuroimaging study, patients with a first-degree FH of AD (FH + ; n = 31) were compared with patients without a FH (FH-; n = 77) on performance and brain activation during visuospatial planning and emotional word encoding. Results were compared with those of healthy controls (HCs) without a FH of AD (n = 31).

RESULTS

FH+ patients performed slower during planning with increasing task load, coupled with stronger blood oxygen level-dependent responses in dorsal prefrontal areas compared with FH- patients and HCs. FH was not associated with performance differences during word encoding, but right insula activation during positive word encoding was present in FH+ patients, comparable with HCs, but absent in FH- patients.

CONCLUSIONS

This study demonstrates subtle impairments during planning in FH+ compared with FH- patients and HCs, whereas activation during mood-incongruent stimuli in FH+ patients was similar to HCs but not FH- patients, suggesting that the presence of a FH of AD is a useful marker for the neurophysiological profile in mood/anxiety disorders and possible predictor for treatment success.

A risk variant for alcoholism in the NMDA receptor affects amygdala activity during fear conditioning in humans

People at high risk for alcoholism show deficits in aversive learning, as indicated by impaired electrodermal responses during fear conditioning, a basic form of associative learning that depends on the amygdala. A positive family history of alcohol dependence has also been related to decreased amygdala responses during emotional processing. In the present study we report reduced amygdala activity during the acquisition of conditioned fear in healthy carriers of a risk variant for alcoholism (rs2072450) in the NR2A subunit-containing N-methyl-d-aspartate (NMDA)-receptor. These results indicate that rs2072450 might confer risk for alcohol dependence through deficient fear acquisition indexed by a diminished amygdala response during aversive learning, and provide a neural basis for a weak behavioral inhibition previously documented in individuals at high risk for alcohol dependence. Carriers of the risk variant additionally exhibit dampened insula activation, a finding that further strengthens our data, given the importance of this brain region in fear conditioning.

White matter microstructure, alcohol exposure, and familial risk for alcohol dependence

Offspring from families with alcohol dependence (AD) have been shown to exhibit brain morphological alterations that appear to be related to their familial/genetic risk for AD. Greater susceptibility for developing AD may be related to structural underpinnings of behavioral traits that predispose to AD. We examined white matter (WM) integrity in 81 individuals with either a high density of AD in their families (N=44) or without a family history for either alcohol or drug dependence (N=37). Magnetic resonance images were acquired on a Siemens 3 T scanner with fractional anistropy (FA) and the apparent diffusion coefficient (ADC), along with radial diffusivity (RD) and longitudinal (axial) diffusivity calculated for major white matter tracts in both hemispheres. Extensive personal histories of alcohol and drug use were available from longitudinal collection of data allowing for reliable estimates of alcohol and drug exposure. We found that the interaction of personal exposure to alcohol and familial risk for AD predicts reduction in WM integrity for the inferior longitudinal fasciculus (ILF) and the superior longitudinal fasciculus (SLF) in the left hemisphere and the forceps major tract. Only one tract showed a significant difference for exposure alone, the anterior thalamic radiation.

[Cognitive vulnerability to alcohol dependence: related neuroanatomic endophenotypes]

INTRODUCTION

Executive function impairments and high level of impulsivity may constitute heritable endophenotypes that confer predisposition for alcohol dependence. Brain volume abnormalities have also been reported in young, alcohol-naïve subjects at high risk (HR) for alcohol dependence, and linked to cognitive dysfunction.

METHODS

This paper presents a literature review of magnetic resonance imaging (MRI) studies that examined brain volumes in adolescent/young adult HR offspring from families with multiple cases of alcohol dependence compared to low risk controls with no family history of alcohol or drug misuse. In some of these studies, executive functioning and externalizing symptoms were also assessed.

RESULTS

In HR subjects, local white matter volume deficits were found in the corpus callosum and in the right orbito-frontal cortex, and lower fractional anisotropy in the left inferior longitudinal fasciculus and in the right optic radiation. Altered fronto-cerebellar connectivity has also been reported. Diminished gray matter volume of the cerebellar cortex was found in HR subjects, in the frontal, cyngulate and para-hippocampal gyri, and also in the amygdala, the thalamus and the cerebellum. These structural abnormalities have been associated with higher impulsivity level and executive function impairments, themselves markers of vulnerability to alcoholism. These premorbid cerebral abnormalities may increase the risk for developing an alcohol use disorder in HR subjects through atypical control processing.

CONCLUSION

Brain abnormalities may potentially constitute an abnormal neural network that might underlie the risk towards alcohol dependence. These circuitry abnormalities might contribute to the reward deficiency, as well as impaired response inhibition that predict impulsive spectrum behavior, which are thought to represent the inherited vulnerability to alcohol dependence in HR individuals.

Reduced orbitofrontal cortical thickness in male adolescents with internet addiction

Background

The orbitofrontal cortex (OFC) has consistently been implicated in the pathology of both drug and behavioral addictions. However, no study to date has examined OFC thickness in internet addiction. In the current study, we investigated the existence of differences in cortical thickness of the OFC in adolescents with internet addiction. On the basis of recently proposed theoretical models of addiction, we predicted a reduction of thickness in the OFC of internet addicted individuals.

Findings

Participants were 15 male adolescents diagnosed as having internet addiction and 15 male healthy comparison subjects. Brain magnetic resonance images were acquired on a 3T MRI and group differences in cortical thickness were analyzed using FreeSurfer. Our results confirmed that male adolescents with internet addiction have significantly decreased cortical thickness in the right lateral OFC (p<0.05).

Conclusion

This finding supports the view that the OFC alterations in adolescents with internet addiction reflect a shared neurobiological marker of addiction-related disorders in general.

Chronic cigarette smoking in alcohol dependence: associations with cortical thickness and N-acetylaspartate levels in the extended brain reward system

Chronic smoking in alcohol dependence is associated with abnormalities in brain morphology and metabolite levels in large lobar regions (e.g. frontal lobe). Here, we evaluated if these abnormalities are specifically apparent in several cortical and select subcortical components of the extended brain reward system (BRS), a network that is critically involved in the development and maintenance of all forms of addictive disorders. We studied 33 non-smoking and 43 smoking alcohol-dependent individuals (ALC) with 1 week of abstinence and 42 non-smoking Controls. At 1.5 Tesla, we obtained regional measures of cortical thickness and N-acetylaspartate (NAA; a surrogate marker of neuronal integrity) concentration in major components of the BRS as well as the corresponding measures throughout the cortex. Smoking ALC and non-smoking ALC demonstrated decreased thickness compared with Controls in the dorsolateral prefrontal cortex (DLPFC), insula, orbitofrontal cortex (OFC), the total BRS, total frontal cortex and global cortex. Smoking ALC had significantly decreased thickness compared to non-smoking ALC in the ACC, insula, the total BRS and total frontal cortex. Smoking ALC had also lower NAA concentrations than both non-smoking ALC and Controls in the DLPFC, insula, superior corona radiata and the total BRS. Alcohol consumption and common medical and psychiatric co-morbidities did not mediate differences between smoking and non-smoking ALC. This dual modality magnetic resonance (MR) study indicated that chronic smoking in ALC was associated with significant cortical thinning and NAA abnormalities in anterior brain regions that are implicated in the development and maintenance of addictive disorders.

Caudate Volume in Offspring at Ultra High Risk for Alcohol Dependence: COMT Val158Met, DRD2, Externalizing Disorders, and Working Memory

BACKGROUND

There is emerging evidence that the increased susceptibility to developing alcohol and substance use disorders in those with a family history of Alcohol Dependence (AD) may be related to structural differences in brain circuits that influence the salience of rewards or modify the efficiency of information processing. Externalizing disorders of childhood including Attention Deficit Hyperactivity Disorder, Conduct and Oppositional Disorders are a prominent feature of those with a positive family history. The caudate nuclei have been implicated in both the salience of rewards and in the pathophysiology of alcohol dependence and these often antecedent childhood disorders.

METHODS

Adolescent/young adult high and low-risk for AD offspring (N = 130) were studied using magnetic resonance imaging. Volumes of the caudate nucleus were obtained using manual tracing with BRAINS2 software and neuropsychological functioning determined. Childhood disorders were assessed as part of a long-term longitudinal follow-up that includes young adult assessment. Dopaminergic variation was assessed using genotypic variation in the catechol-O-methyltransferase (COMT) and DRD2 genes.

RESULTS

High-risk subjects showed poorer Working Memory functioning. Cau-date volume did not differ between high and low-risk subjects, but those with externalizing disorders of childhood showed reduced caudate volume. Variation in COMT and DRD2 genes was associated with Working Memory performance and caudate volume.

CONCLUSIONS

Caudate volume is reduced in association with externalizing disorders of childhood/adolescence. Working Memory deficits appear in familial high-risk offspring and those with externalizing disorders of childhood. The dopaminergic system appears to be involved in both working memory performance and externalizing disorders of childhood.

The relationship of appetitive, reproductive and posterior pituitary hormones to alcoholism and craving in humans

A significant challenge for understanding alcoholism lies in discovering why some, but not other individuals, become dependent on alcohol. Genetic, environmental, cultural, developmental, and neurobiological influences are recognized as essential factors underlying a person's risk for becoming alcohol dependent (AD); however, the neurobiological processes that trigger this vulnerability are still poorly understood. Hormones are important in the regulation of many functions and several hormones are strongly associated with alcohol use. While medical consequences are important, the primary focus of this review is on the underlying confluence of appetitive/feeding, reproductive and posterior pituitary hormones associated with distinct phases of alcoholism or assessed by alcohol craving in humans. While these hormones are of diverse origin, the involvement with alcoholism by these hormone systems is unmistakable, and demonstrates the complexity of interactions with alcohol and the difficulty of successfully pursuing effective treatments. Whether alcohol associated changes in the activity of certain hormones are the result of alcohol use or are the result of an underlying predisposition for alcoholism, or a combination of both, is currently of great scientific interest. The evidence we present in this review suggests that appetitive hormones may be markers as they appear involved in alcohol dependence and craving, that reproductive hormones provide an example of the consequences of drinking and are affected by alcohol, and that posterior pituitary hormones have potential for being targets for treatment. A better understanding of the nature of these associations may contribute to diagnosing and more comprehensively treating alcoholism. Pharmacotherapies that take advantage of our new understanding of hormones, their receptors, or their potential relationship to craving may shed light on the treatment of this disorder.

Loss in connectivity among regions of the brain reward system in alcohol dependence

A recently developed measure of structural brain connectivity disruption, the loss in connectivity (LoCo), is adapted for studies in alcohol dependence. LoCo uses independent tractography information from young healthy controls to project the location of white matter (WM) microstructure abnormalities in alcohol-dependent versus nondependent individuals onto connected gray matter (GM) regions. LoCo scores are computed from WM abnormality masks derived at two levels: (1) groupwise differences of alcohol-dependent individuals (ALC) versus light-drinking (LD) controls and (2) differences of each ALC individual versus the LD control group. LoCo scores based on groupwise WM differences show that GM regions belonging to the extended brain reward system (BRS) network have significantly higher LoCo (i.e., disconnectivity) than those not in this network (t = 2.18, P = 0.016). LoCo scores based on individuals' WM differences are also higher in BRS versus non-BRS (t = 5.26, P = 3.92 × 10(-6) ) of ALC. These results suggest that WM alterations in alcohol dependence, although subtle and spatially heterogeneous across the population, are nonetheless preferentially localized to the BRS. LoCo is shown to provide a more sensitive estimate of GM involvement than conventional volumetric GM measures by better differentiating between brains of ALC and LD controls (rates of 89.3% vs. 69.6%). However, just as volumetric measures, LoCo is not significantly correlated with standard metrics of drinking severity. LoCo is a sensitive WM measure of regional cortical disconnectivity that uniquely characterizes anatomical network disruptions in alcohol dependence.

Adolescent brain development, substance use, and psychotherapeutic change

Adolescence is a unique developmental period characterized by major physiological, psychological, social, and brain changes, as well as an increased incidence of maladaptive, addictive behaviors. With the use of MRI techniques, researchers have been able to provide a better understanding of adolescent brain maturation and how neurodevelopment affects cognition and behavior. This review discusses adolescent brain development and its potential influence on psychotherapeutic change. We focus on cognitive-behavioral and mindfulness-based approaches for treating substance use and highlight potential brain mechanisms underlying response to psychotherapy. Finally, we discuss integrative neuroimaging and treatment studies and potential opportunities for advancing the treatment of adolescent addictive behaviors.

ASTN1 and alcohol dependence: family-based association analysis in multiplex alcohol dependence families

A previous genome-wide linkage study of alcohol dependence (AD) in multiplex families found a suggestive linkage result for a region on Chromosome 1 near microsatellite markers D1S196 and D1S2878. The ASTN1 gene is in this region, a gene previously reported to be associated with substance abuse, bipolar disorder and schizophrenia. Using the same family data consisting of 330 individuals with phenotypic data and DNA, finer mapping of a 26 cM region centered on D1S196 was undertaken using SNPs with minor allele frequency (MAF) ≥ 0.15 and pair-wise linkage disequilibrium (LD) of r(2) < 0.8 using the HapMap CEU population. Significant FBAT P-values for SNPs within the ASTN1 gene were observed for four SNPs (rs465066, rs228008, rs6668092, and rs172917), the most significant, rs228008, within intron 8 had a P-value of 0.001. Using MQLS, which allows for inclusion of all families, we find three of these SNPs with MQLS P-values < 0.003. In addition, two additional neighboring SNPs (rs10798496 and rs6667588) showed significance at P = 0.002 and 0.03, respectively. Haplotype analysis was performed using the haplotype-based test function of FBAT for a block that included rs228008, rs6668092, and rs172917. This analysis found one block (GCG) over-transmitted and another (ATA) under-transmitted to affected offspring. Linkage analysis identified a region consistent with the association results. Family-based association analysis shows the ASTN1 gene significantly associated with alcohol dependence. The potential importance of the ASTN1 gene for AD risk may be related its role in glial-guided neuronal migration.

Orbitofrontal volumes in early adolescence predict initiation of cannabis use: a 4-year longitudinal and prospective study

BACKGROUND

There is growing evidence that long-term, heavy cannabis use is associated with alterations in regional brain volumes. Although these changes are frequently attributed to the neurotoxic effects of cannabis, it is possible that some abnormalities might predate use and represent markers of vulnerability. To date, no studies have examined whether structural brain abnormalities are present before the onset of cannabis use. This study aims to determine whether adolescents who have initiated cannabis use early (i.e., before age 17 years) show premorbid structural abnormalities in the amygdala, hippocampus, orbitofrontal cortex, and anterior cingulate cortex.

METHODS

Participants (n = 121) were recruited from primary schools in Melbourne, Australia, as part of a larger study examining adolescent emotional development. Participants underwent structural magnetic resonance imaging at age 12 years and were assessed for cannabis use 4 years later, at age 16 years. At the follow-up assessment, 28 participants had commenced using cannabis (16 female subjects [57%]), and 93 had not (43 female subjects [46%]).

RESULTS

Smaller orbitofrontal cortex volumes at age 12 years predicted initiation of cannabis use by age 16 years. The volumes of other regions (amygdala, hippocampus, and anterior cingulate cortex) did not predict later cannabis use.

CONCLUSIONS

These findings suggest that structural abnormalities in the orbitofrontal cortex might contribute to risk for cannabis exposure. Although the results have important implications for understanding neurobiological predictors of cannabis use, further research is needed to understand their relationship with heavier patterns of use in adulthood as well as later abuse of other substances.

A comprehensive assessment of neurocognition in middle-aged chronic cigarette smokers

BACKGROUND

The majority of studies investigating the neurocognitive consequences of chronic smoking have been conducted with adults 60 years and older. Therefore, the scope of neurocognitive dysfunction associated with chronic cigarette smoking in middle age (i.e., 30-60 age range) has not been fully delineated.

METHODS

Twenty-seven (44±9 years of age; 4 females) non-smoking and 30 smoking (49±8 years of age; 4 females) participants completed a comprehensive neurocognitive battery and measures of fine motor dexterity and postural stability. All participants were free of biomedical or psychiatric conditions that may have influenced neurocognitive and motor function.

RESULTS

Smokers performed significantly worse than non-smokers on the following domains: auditory-verbal and visuospatial learning, visuospatial memory, cognitive efficiency, executive skills, general intelligence, processing speed, fine motor dexterity and postural stability. The differences between smokers and non-smokers evidenced moderate to strong effect sizes and were not mediated by age, education, vocational level, estimated verbal intelligence or alcohol consumption. In smokers, a greater number of lifetime years of smoking was related to poorer performance on measures of cognitive efficiency, processing speed and visuospatial skills.

CONCLUSIONS

Results from this middle-aged cohort replicated previous research and provides novel findings indicating that chronic smoking was associated with inferior performance on measures of general intelligence, visuospatial learning and memory and fine motor dexterity. Research that relates measures of neurobiological function/integrity to neurocognition is needed to better understand the mechanisms contributing to the poorer performance across multiple domains demonstrated by smokers.

White matter integrity as a link in the association between motivation to abstain and treatment outcome in adolescent substance users

Readiness to change constitutes an important treatment target. This study examined white matter (WM) integrity as a possible link in the pathway between motivation to abstain and treatment outcome. Adolescents (age 14-18 years, n = 32) were recruited from intensive outpatient (IOP) substance use treatment and reported on motivation to abstain from alcohol and marijuana shortly after treatment admission (i.e., at baseline). Diffusion tensor imaging data were collected approximately 7 weeks after starting IOP and were used to quantify WM integrity (indexed by fractional anisotropy, FA) using a region of interest (ROI) approach. Treatment outcomes were assessed 6 months after baseline. Indirect effects analyses tested FA in prefrontal, orbitofrontal, and temporal ROIs as a linking variable in the pathway from motivation to abstain to alcohol and marijuana outcomes. Bivariate correlations indicated that greater motivation to abstain from alcohol was associated with lower FA in prefrontal, orbitofrontal, and temporal ROIs and that lower FA in these three ROIs was associated with greater 6-month alcohol problem severity. The indirect effect of FA was significant for the prefrontal ROI in the pathway from motivation to outcome for alcohol. FA values were not associated with motivation to abstain from marijuana or marijuana-related outcomes. Results suggest that lower WM integrity, particularly in the prefrontal brain region, may help to explain greater alcohol problem severity at 6 months despite higher motivation to abstain from alcohol. Interventions that aim to enhance WM integrity warrant attention to improve adolescent treatment outcomes.

Frontal white matter integrity predictors of adult alcohol treatment outcome

BACKGROUND

Previous research has associated abnormalities in frontal lobe functioning with alcohol relapse. In this study, we used diffusion tensor imaging to investigate whether frontal white matter integrity measured at the start of treatment differs between persons with alcohol use disorders (AUD) who sustain treatment gains and those who return to heavy use after treatment.

METHODS

Forty-five treatment-seeking AUD inpatients and 30 healthy control subjects were included in the study. Six months after completing treatment, 16 of the AUD participants had resumed heavy use (RHU) and 29 others remained abstinent or drank minimally (treatment sustainers [TS]). Voxel-wise group comparisons (TS vs. RHU) were performed on fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity maps generated from each subject's diffusion tensor imaging scan at the start of treatment.

RESULTS

We found significantly lower FA and significantly higher RD in the frontal lobes of the RHU group, relative to the TS group. The RHU group data are consistent with previous reports of abnormal frontal white matter tract abnormalities in persons with AUD.

CONCLUSIONS

It is possible that the lower FA and higher RD in the RHU group reflect microstructural injury to frontal circuitries, and these may underlie the reduced cognitive control amid heightened reward sensitivity associated with resumption of heavy drinking.

Remapping the brain to compensate for impairment in recovering alcoholics

Abnormal brain activity may reflect compensation when observed in patients who perform normally on tests requiring functions usually observed as impaired. Operational criteria defining compensation have been described and aid in distinguishing compensatory from chance events. Here, we tested whether previously published functional magnetic resonance imaging data acquired in 15 recovering alcoholics and 15 controls at rest and while performing a spatial working memory task would fulfill criteria defining functional compensation. Multivariate analysis tested how well abnormal activation in the affected group predicted normal performance, despite low or no activation in brain regions invoked by controls to accomplish the same task. By identifying networks that uniquely and positively correlated with good performance, we provide evidence for compensatory recruitment of cerebellar-based functional networks by alcoholics. Whereas controls recruited prefrontal-cerebellar regions VI/Crus I known to subserve working memory, alcoholics recruited 2 other parallel frontocerebellar loops: dorsolateral prefrontal cortex (DLPFC)-cerebellar VIII system during rest and DLPFC-cerebellar VI system while task engaged. Greater synchronous activity between cerebellar lobule VIII and DLPFC at rest and greater activation within cerebellar lobule VI and DLPFC during task predicted better working memory performance. Thus, higher intrinsic cerebellar activity in alcoholics was an adequate condition for triggering task-relevant activity in the frontal cortex required for normal working memory performance.