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

Regional cortical thickness recovery with extended abstinence after treatment in those with alcohol use disorder

Several cross-sectional investigations reported widespread cortical thinning in those with alcohol use disorder (AUD). The few longitudinal studies investigating cortical thickness changes during abstinence are limited to the first month of sobriety. Consequently, cortical thickness changes during extended abstinence in those with AUD is unclear. In this study, AUD participants were studied at approximately 1 week (n = 68), 1 month (n = 88), and 7.3 months (n = 40) of abstinence. Forty-five never-smoking controls (CON) completed a baseline study, and 15 were reassessed after approximately 9.6 months. Participants completed magnetic resonance imaging studies at 1.5T, and cortical thickness for 34 bilateral regions of interest (ROI) was quantitated with FreeSurfer. AUD participants demonstrated significant linear thickness increases in 25/34 ROI over 7.3 months of abstinence. The rate of change from 1 week to 1 month was greater than 1 month to 7.3 months in 19/34 ROIs. Proatherogenic conditions were associated with lower thickness recovery in anterior frontal, inferior parietal, and lateral/mesial temporal regions. After 7.3 months of abstinence, AUD participants were statistically equivalent to CON on cortical thickness in 24/34 ROIs; the cortical thickness differences between AUD and CON in the banks superior temporal gyrus, post central, posterior cingulate, superior parietal, supramarginal, and superior frontal cortices were driven by thinner cortices in AUD with proatherogenic conditions relative to CON. In actively smoking AUD, increasing pack-years was associated with decreasing thickness recovery primarily in the anterior frontal ROIs. Widespread bilateral cortical thickness recovery over 7.3 months of abstinence was the central finding for this AUD cohort. The longitudinal and cross-sectional findings for AUD with proatherogenic suggests alterations in perfusion or vascular integrity may relate to structural recovery in those with AUD. These results support the adaptive and beneficial effects of sustained sobriety on brain structural recovery in people with AUD.

Regional cortical brain volumes at treatment entry relates to post treatment WHO risk drinking levels in those with alcohol use disorder

BACKGROUND

Abstinence following treatment for alcohol use disorder (AUD) is associated with significant improvements in psychiatric and physical health, however, recent studies suggest resumption of low risk levels of alcohol use can also be beneficial. The present study assessed whether post-treatment levels of alcohol use were associated with cortical brain volumedifferences at treatment entry.

METHODS

Individuals seeking treatment for AUD (n=75) and light/non-drinking controls (LN, n=51) underwent 1.5T magnetic resonance imaging. The volumes of 34 bilateral cortical regions of interest (ROIs) were quantitated via FreeSurfer. Individuals with AUD were classified according to post-treatment alcohol consumption using the WHO risk drinking levels (abstainers: AB; low risk: RL; or higher risk: RH). Regional volumes for AB, RL and RH, at treatment entry, were compared to LN.

RESULTS

Relative to LN, AB demonstrated smaller volumes in 18/68 (26%), RL in 24/68 (35%) and RH in 34/68 (50%) ROIs with the largest magnitude volume differences observed between RH and LN. RH and RL reported a higher frequency of depressive disorders than AB. Among RH and RL, level of depressive and anxiety symptomatology were associated with daily number of drinks consumed after treatment.

CONCLUSIONS

Volumetric differences, at treatment entry, in brain regions implicated in executive function and salience networks corresponded with post-treatment alcohol consumption levels suggesting that pre-existing differences in neural integrity may contribute to treatment outcomes. Depressive and anxiety symptomatology was also associated with brain morphometrics and alcohol use patterns, highlighting the importance of effectively targeting these conditions during AUD treatment.

BDNF rs6265 Met carriers with alcohol use disorder show greater age-related decline of N-acetylaspartate in left dorsolateral prefrontal cortex

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is implicated in neuronal and glial cell growth and differentiation, synaptic plasticity, and apoptotic mechanisms. A single-nucleotide polymorphism of the BDNF rs6265 gene may contribute to the pattern and magnitude of brain metabolite abnormalities apparent in those with an Alcohol Use Disorder (AUD). We predicted that Methionine (Met) carriers would demonstrate lower magnetic resonance spectroscopy (MRS) measures of N-acetylaspartate level (NAA) and greater age-related decline in NAA than Valine (Val) homozygotes.

METHODS

Veterans with AUD (n=95; 46±12 years of age, min = 25, max = 71) were recruited from VA Palo Alto residential treatment centers. Single voxel MRS, at 3 Tesla, was used to obtain NAA, choline (Cho) and creatine (Cr) containing compounds from the left dorsolateral prefrontal cortex (DLPFC). Metabolite spectra were fit with LC Model and NAA and Cho were standardized to total Cr level and NAA was also standardized to Cho.

RESULTS

Val/Met (n=35) showed markedly greater age-related decline in left DLPFC NAA/Cr level than Val/Val (n=60); no differences in mean metabolite levels were observed between Val/Met and Val/Val. Val/Met demonstrated greater frequency of history of MDD and higher frequency of cannabis use disorder over 12 months prior to study.

CONCLUSIONS

The greater age-related decline in left DLPFC NAA/Cr and the higher frequency of MDD history and Cannabis Use disorder in BDNF rs6265 Met carriers with AUD are novel and may have implications for non-invasive brain stimulation targeting the left DLFPC and other psychosocial interventions typically utilized in the treatment of AUD.

Associations between right inferior frontal gyrus morphometry and inhibitory control in individuals with nicotine dependence

BACKGROUND

The hyperdirect pathway - a circuit involved in executing inhibitory control (IC) - is dysregulated among individuals with nicotine dependence. The right inferior frontal gyrus (rIFG), a cortical input to the hyperdirect circuit, has been shown to be functionally and structurally altered among nicotine-dependent people who smoke. The rIFG is composed of 3 cytoarchitecturally distinct subregions: The pars opercularis, pars triangularis, and pars orbitalis. The present study assessed the relationship between rIFG subregion morphometry and inhibitory control among individuals with nicotine dependence.

METHODS

Behavioral and magnetic resonance brain imaging (MRI) data from 127 nicotine-dependent adults who smoke (MFTND = 5.4, ± 1.9; MCPD = 18.3, ± 7.0; Myears = 25.04, ± 11.97) (Mage = 42.9, ± 11.1) were assessed. Brain morphometry was assessed from T1-weighted MRIs using Freesurfer. IC was assessed with a response-inhibition Go/Go/No-Go (GGNG) task and a smoking relapse analog task (SRT).

RESULTS AND CONCLUSIONS

Vertex-wise analyses revealed that GGNG task scores were positively associated with cortical thickness and volume in the right pars triangularis (cluster-wise p = 0.006, 90% CI = 0.003 - 0.009; cluster-wise p = 0.040, 90% CI = 0.032 - 0.048), and the ability to inhibit ad lib smoking during the SRT was positively associated with cortical thickness in the right pars orbitalis (cluster-wise p = 0.011, 90% CI = 0.007 - 0.015). Our results indicate that cortical thickness of distinct rIFG subregions may serve as biomarkers for unique forms of IC deficits.

Effect of Aerobic Exercise on Intestinal Microbiota with Amino Acids and Short-Chain Fatty Acids in Methamphetamine-Induced Mice

This study aimed to investigate the changes in intestinal homeostasis and metabolism in mice after methamphetamine (MA) administration and exercise intervention. In this study, male C57BL/B6J mice were selected to establish a model of methamphetamine-induced addiction, and the gut microbiota composition, short-chain fatty acids (SCFAs), and amino acid levels were assessed by 16S rRNA, liquid chromatography–tandem mass spectrometry, and gas chromatography–tandem mass spectrometry, respectively. The results showed that 23 dominant microbiota, 12 amino acids, and 1 SCFA were remarkably higher and 9 amino acids and 6 SCFAs were remarkably lower in the exercise model group than in the control group. Among the top 10 markers with opposite trends between the exercise intervention group and model group, the differential microbiomes included Oscillibacter, Alloprevotella, Colidextribacter, Faecalibaculum, Uncultured, Muribaculaceae, and Negativibacillus; amino acids included proline; and SCFAs included isovaleric acid and pentanoic acid. Proline was negatively correlated with Negativibacillus and positively correlated with pentanoic acid. The results suggested that moderate-intensity aerobic exercise may modulate changes in the composition of the gut microbiota and the levels of amino acids and SCFAs induced by MA administration.

Cortical thickness and curvature abnormalities in patients with major depressive disorder with childhood maltreatment: Neural markers of vulnerability?

BACKGROUND

Childhood maltreatment has been related to various disadvantageous lifetime outcomes. However, the brain structural alterations that occur in major depressive disorder (MDD) patients with childhood maltreatment are incompletely investigated.

METHODS

We extensively explored the cortical abnormalities including cortical volume, surface area, thickness, sulcal depth, and curvature in maltreated MDD patients. Twoway ANOVA was performed to distinguish the effects of childhood maltreatment and depression on structural abnormalities. Partial correlation analysis was performed to explore the relationship between childhood maltreatment and cortical abnormalities. Moreover, we plotted the receiver operating characteristic curve to examine whether the observed cortical abnormalities could be used as neuro biomarkers to identify maltreated MDD patients.

RESULTS

We reach the following findings: (i) relative to MDD without childhood maltreatment, MDD patients with childhood maltreatment existed increased cortical curvature in inferior frontal gyrus; (ii) compared to HC without childhood maltreatment, decreased cortical thickness was observed in anterior cingulate cortex and medial prefrontal cortex in MDD patients with childhood maltreatment; (iii) we confirmed the inseparable relationship between cortical curvature alterations in inferior frontal gyrus as well as childhood maltreatment; (iv) cortical curvature abnormality in inferior frontal gyrus could be applied as neural biomarker for clinical identification of MDD patients with childhood maltreatment.

CONCLUSIONS

Childhood maltreatment have a significant effects on cortical thickness and curvature abnormalities involved in inferior frontal gyrus, anterior cingulate cortex and medial prefrontal cortex, constituting the vulnerability to depression.

Sex-dependent risk factors for PTSD: a prospective structural MRI study

Female individuals are more likely to be diagnosed with PTSD following trauma exposure than males, potentially due, in part, to underlying neurobiological factors. Several brain regions underlying fear learning and expression have previously been associated with PTSD, with the hippocampus, amygdala, dorsal anterior cingulate cortex (dACC), and rostral ACC (rACC) showing altered volume and function in those with PTSD. However, few studies have examined how sex impacts the predictive value of subcortical volumes and cortical thickness in longitudinal PTSD studies. As part of an emergency department study completed at the Grady Trauma Project in Atlanta, GA, N = 93 (40 Female) participants were enrolled within 24 h following a traumatic event. Multi-echo T1-weighted MRI images were collected one-month post-trauma exposure. Bilateral amygdala and hippocampal volumes and rACC and dACC cortical thickness were segmented. To assess the longitudinal course of PTSD, the PTSD Symptom Scale (PSS) was collected 6 months post-trauma. We investigated whether regional volume/thickness interacted with sex to predict later PTSD symptom severity, controlling for PSS score at time of scan, age, race, and trauma type, as well as intracranial volume (ICV) for subcortical volumes. There was a significant interaction between sex and rACC for 6-month PSS, such that right rACC thickness was positively correlated with 6-month PSS scores in females, but not in males. In examining PTSD symptom subtypes and depression symptoms, greater rACC thickness in females predicted greater avoidance symptoms, while smaller rACC thickness in males predicted greater depression symptoms. Amygdala and hippocampus volume and dACC thickness showed no main effect or interaction with sex. The current findings provide evidence for sex-based differences in how brain volume predicts future PTSD severity and symptoms and supports the rACC as being a vital region regarding PTSD. Gender differences should be assessed in future longitudinal PTSD MRI studies for more accurate identification of future PTSD risk following trauma.

The impact of smoking status on cognition and brain morphology in schizophrenia spectrum disorders

BACKGROUND

Cigarette smoking is associated with worse cognition and decreased cortical volume and thickness in healthy cohorts. Chronic cigarette smoking is prevalent in schizophrenia spectrum disorders (SSD), but the effects of smoking status on the brain and cognition in SSD are not clear. This study aimed to understand whether cognitive performance and brain morphology differed between smoking and non-smoking individuals with SSD compared to healthy controls.

METHODS

Data were obtained from the Australian Schizophrenia Research Bank. Cognitive functioning was measured in 299 controls and 455 SSD patients. Cortical volume, thickness and surface area data were analysed from T1-weighted structural scans obtained in a subset of the sample (n = 82 controls, n = 201 SSD). Associations between smoking status (cigarette smoker/non-smoker), cognition and brain morphology were tested using analyses of covariance, including diagnosis as a moderator.

RESULTS

No smoking by diagnosis interactions were evident, and no significant differences were revealed between smokers and non-smokers across any of the variables measured, with the exception of a significantly thinner left posterior cingulate in smokers compared to non-smokers. Several main effects of smoking in the cognitive, volume and thickness analyses were initially significant but did not survive false discovery rate (FDR) correction.

CONCLUSIONS

Despite the general absence of significant FDR-corrected findings, trend-level effects suggest the possibility that subtle smoking-related effects exist but were not uncovered due to low statistical power. An investigation of this topic is encouraged to confirm and expand on our findings.

Cortical surface variation in individuals with excessive smartphone use

Excessive smartphone use has been repeatedly related to adverse effects on mental health and psychological well-being in young adults. The continued investigation of the neurobiological mechanism underlying excessive smartphone use - sometimes also referred to as "smartphone addiction" (SPA) - is considered a top priority in system neuroscience research. Despite progress in the past years, cortical morphology associated with SPA is still poorly understood. Here, we used structural magnetic resonance imaging (MRI) at 3 T to investigate two cortical surface markers of distinct neurodevelopmental origin such as the complexity of cortical folding (CCF) and cortical thickness (CTh) in individuals with excessive smartphone use (n = 19) compared to individuals not fulfilling SPA criteria (n-SPA; n = 22). SPA was assessed using the Smartphone Addiction Inventory (SPAI). CCF and CTh were investigated using the Computational Anatomy Toolbox (CAT12). SPA individuals showed lower CCF in the right superior frontal gyrus as well as in the right caudal (cACC) and rostral anterior cingulate cortex (rACC) compared to n-SPA individuals (TFCE, uncorrected at p < 0.001). Following a dimensional approach, across the entire sample CCF of the right cACC was significantly associated with SPAI total score, as well as with distinct SPAI subdimensions, particularly time spent with the device, compulsivity, and sleep interference in all participants (n = 41; p < 0.05, FDR-corrected). Collectively, these findings suggest that SPA is associated with aberrant structural maturation of regions important for cognitive control and emotional regulation. This article is protected by copyright. All rights reserved.

Longitudinal Structural Brain Changes in Bipolar Disorder: A Multicenter Neuroimaging Study of 1232 Individuals by the ENIGMA Bipolar Disorder Working Group

BACKGROUND

Bipolar disorder (BD) is associated with cortical and subcortical structural brain abnormalities. It is unclear whether such alterations progressively change over time, and how this is related to the number of mood episodes. To address this question, we analyzed a large and diverse international sample with longitudinal magnetic resonance imaging (MRI) and clinical data to examine structural brain changes over time in BD.

METHODS

Longitudinal structural MRI and clinical data from the ENIGMA (Enhancing Neuro Imaging Genetics through Meta Analysis) BD Working Group, including 307 patients with BD and 925 healthy control subjects, were collected from 14 sites worldwide. Male and female participants, aged 40 ± 17 years, underwent MRI at 2 time points. Cortical thickness, surface area, and subcortical volumes were estimated using FreeSurfer. Annualized change rates for each imaging phenotype were compared between patients with BD and healthy control subjects. Within patients, we related brain change rates to the number of mood episodes between time points and tested for effects of demographic and clinical variables.

RESULTS

Compared with healthy control subjects, patients with BD showed faster enlargement of ventricular volumes and slower thinning of the fusiform and parahippocampal cortex (0.18 <d < 0.22). More (hypo)manic episodes were associated with faster cortical thinning, primarily in the prefrontal cortex.

CONCLUSIONS

In the hitherto largest longitudinal MRI study on BD, we did not detect accelerated cortical thinning but noted faster ventricular enlargements in BD. However, abnormal frontocortical thinning was observed in association with frequent manic episodes. Our study yields insights into disease progression in BD and highlights the importance of mania prevention in BD treatment.

Alcohol and Vaporized Nicotine Co-Exposure During Adolescence Contribute Differentially to Sex-Specific Behavioral Effects in Adulthood

INTRODUCTION

Co-occurrence of e-cigarette use and alcohol consumption during adolescence is frequent. Here, we examined whether adolescent co-exposure to alcohol drinking and vaporized nicotine would impact reward- and cognition-related behaviors in adult male and female rats during adulthood.

METHODS

Four groups of male and female Sprague Dawley rats (n=8-11/group/sex) received either nicotine (JUUL 5% nicotine pods) or vehicle vapor for 10 minutes daily between postnatal days 30-46, while having continuous voluntary access to ethanol and water during this time in a two-bottle preference design. Upon reaching adulthood, all rats underwent behavioral testing (i.e., Pavlovian conditioned approach testing, fear conditioning and a two-bottle alcohol preference).

RESULTS

A sex-dependent effect, not related to adolescent nicotine or alcohol exposure, on alcohol drinking in adulthood was found, such that females had a higher intake and preference for alcohol compared to males; both male and female adult rats also had greater alcohol preference compared to their alcohol preference as adolescents. Male rats exposed to vaporized nicotine with or without alcohol drinking during adolescence exhibited altered reward-related learning in adulthood, evidenced by enhanced levels of sign-tracking behavior. Male rats that drank alcohol with or without nicotine vapor in adolescence showed deficits in associative fear learning and memory as adults. In contrast, these effects were not seen in female rats exposed to alcohol and nicotine vapor during adolescence.

CONCLUSIONS

The present study provides evidence that co-exposure to alcohol and vaporized nicotine during adolescence in male, but not female, rats produces long-term changes in reward- and cognition-related behaviors.

IMPLICATIONS

These findings enhance our understanding of the effects of alcohol drinking and nicotine vapor exposure in adolescence. Moreover, they highlight potential sex differences that exist in the response to alcohol and nicotine vapor, underscoring the need for follow-up studies elucidating the neurobiological mechanisms that drive these sex differences, as well as the long-term effects of alcohol and nicotine vapor use.

Genetic risk for bipolar disorder and schizophrenia predicts structure and function of the ventromedial prefrontal cortex

BACKGROUND

Bipolar disorder is highly heritable and polygenic. The polygenic risk for bipolar disorder overlaps with that of schizophrenia, and polygenic scores are normally distributed in the population. Bipolar disorder has been associated with structural brain abnormalities, but it is unknown how these are linked to genetic risk factors for psychotic disorders.

METHODS

We tested whether polygenic risk scores for bipolar disorder and schizophrenia predict structural brain alterations in 98 patients with bipolar disorder and 81 healthy controls. We derived brain cortical thickness, surface area and volume from structural MRI scans. In post-hoc analyses, we correlated polygenic risk with functional hub strength, derived from resting-state functional MRI and brain connectomics.

RESULTS

Higher polygenic risk scores for both bipolar disorder and schizophrenia were associated with a thinner ventromedial prefrontal cortex (vmPFC). We found these associations in the combined group, and separately in patients and drug-naive controls. Polygenic risk for bipolar disorder was correlated with the functional hub strength of the vmPFC within the default mode network.

LIMITATIONS

Polygenic risk is a cumulative measure of genomic burden. Detailed genetic mechanisms underlying brain alterations and their cognitive consequences still need to be determined.

CONCLUSION

Our multimodal neuroimaging study linked genomic burden and brain endophenotype by demonstrating an association between polygenic risk scores for bipolar disorder and schizophrenia and the structure and function of the vmPFC. Our findings suggest that genetic factors might confer risk for psychotic disorders by influencing the integrity of the vmPFC, a brain region involved in self-referential processes and emotional regulation. Our study may also provide an imaging-genetics vulnerability marker that can be used to help identify individuals at risk for developing bipolar disorder.

Gut dysbiosis associated with the rats' responses in methamphetamine-induced conditioned place preference

Methamphetamine (MA) is a potent stimulant and notoriously addictive. Individuals respond to MA effects differently and thus have a varying susceptible risk of developing MA use disorder. Cumulative evidence has indicated that gut dysbiosis contributes to behavioral response to drug effects. However, the role of gut microbiota in the susceptible risk of developing MA use disorder has remained elusive. Using an MA-induced conditioned place preference (CPP) rat model, we administrated the same dose of MA to rats, which then showed distinct preferences in drug-related place, indicating their different responses to MA. From all of the MA-exposed rats, the eight with the highest CPP scores were labeled as group high CPP (H-CPP), and the eight with the lowest were labeled as group low CPP (L-CPP). By 16S ribosomal RNA (rRNA) sequencing, we found that the gut microbiota compositions differed between H-CPP and L-CPP. Specifically, Akkermansia was significantly higher in H-CPP and positively correlated with the CPP scores. Notably, H-CPP and L-CPP differed in the gut microbiota composition prior to the CPP training; Ruminococcus was the dominant phylotype in H-CPP at baseline. More importantly, rats pretreated by antibiotics showed a significantly stronger MA-induced CPP than did the controls. Our study demonstrates that the gut dysbiosis was associated with the MA-induced CPP, indicating that the gut microbiota might be important modulators for MA-induced behavior and vulnerability to MA use disorder.

Daily and intermittent smoking are associated with low prefrontal volume and low concentrations of prefrontal glutamate, creatine, myo-inositol, and N-acetylaspartate

Cigarette smoking is still the largest contributor to disease and death worldwide. Successful cessation is hindered by decreases in prefrontal glutamate concentrations and gray matter volume due to daily smoking. Because nondaily, intermittent smoking also contributes greatly to disease and death, understanding whether infrequent tobacco use is associated with reductions in prefrontal glutamate concentrations and gray matter volume may aid public health. Eighty-five young participants (41 nonsmokers, 24 intermittent smokers, 20 daily smokers, mean age ~23 years old), underwent ¹ H-magnetic resonance spectroscopy of the medial prefrontal cortex, as well as structural magnetic resonance imaging (MRI) to determine whole-brain gray matter volume. Compared with nonsmokers, both daily and intermittent smokers exhibited lower concentrations of glutamate, creatine, N-acetylaspartate, and myo-inositol in the medial prefrontal cortex, and lower gray matter volume in the right inferior frontal gyrus; these measures of prefrontal metabolites and structure did not differ between daily and intermittent smokers. Finally, medial prefrontal metabolite concentrations and right inferior frontal gray matter volume were positively correlated, but these relationships were not influenced by smoking status. This study provides the first evidence that both daily and intermittent smoking are associated with low concentrations of glutamate, creatine, N-acetylaspartate, and myo-inositol and low gray matter volume in the prefrontal cortex. Future tobacco cessation efforts should not ignore potential deleterious effects of intermittent smoking by considering only daily smokers. Finally, because low glutamate concentrations hinder cessation, treatments that can normalize tonic levels of prefrontal glutamate, such as N-acetylcysteine, may help intermittent and daily smokers to quit.

The gray matter structural connectome and its relationship to alcohol relapse: Reconnecting for recovery

Gray matter (GM) atrophy associated with alcohol use disorders (AUD) affects predominantly the frontal lobes. Less is known how frontal lobe GM loss affects GM loss in other regions and how it influences drinking behavior or relapse after treatment. The profile similarity index (PSI) combined with graph analysis allows to assess how GM loss in one region affects GM loss in regions connected to it, ie, GM connectivity. The PSI was used to describe the pattern of GM connectivity in 21 light drinkers (LDs) and in 54 individuals with AUD (ALC) early in abstinence. Effects of abstinence and relapse were determined in a subgroup of 36 participants after 3 months. Compared with LD, GM losses within the extended brain reward system (eBRS) at 1-month abstinence were similar between abstainers (ABST) and relapsers (REL), but REL had also GM losses outside the eBRS. Lower GM connectivities in ventro-striatal/hypothalamic and dorsolateral prefrontal regions and thalami were present in both ABST and REL. Between-networks connectivity loss of the eBRS in ABST was confined to prefrontal regions. About 3 months later, the GM volume and connectivity losses had resolved in ABST, and insula connectivity was increased compared with LD. GM losses and GM connectivity losses in REL were unchanged. Overall, prolonged abstinence was associated with a normalization of within-eBRS connectivity and a reconnection of eBRS structures with other networks. The re-formation of structural connectivities within and across networks appears critical for cognitive-behavioral functioning related to the capacity to maintain abstinence after outpatient treatment.

Magnetic resonance spectroscopy studies of substance use disorders: Current landscape and potential future directions

Over 200 in vivo magnetic resonance spectroscopy (MRS) studies of substance use and related disorders (SUD) were published this past decade. The large majority of this work used proton (¹H)-MRS to characterize effects of acute and chronic exposures to drugs of abuse on human brain metabolites including N-acetylaspartate, choline-containing metabolites, creatine plus phosphocreatine, glutamate, and GABA. Some studies used phosphorus (³¹P)-MRS to quantify biomarkers of cerebral metabolism including phosphocreatine and adenosine triphosphate. A few studies used carbon (¹³C)-MRS to quantify intermediary metabolism. This Mini-review discusses select studies that illustrate how MRS can complement neurocircuitry research including by use of multimodal imaging strategies that combine MRS with functional MRI (fMRI) and/or diffusion tensor imaging (DTI). Additionally, magnetic resonance spectroscopic imaging (MRSI), which enables simultaneous multivoxel MRS acquisitions, can be used to better understand and interpret whole-brain functional or structural connectivity data. The review discusses some limitations in MRS methodology and then highlights important knowledge gaps and areas for potential future investigation, including the use of ¹H- and ³¹P-MRS to quantify cerebral metabolism, oxidative stress, inflammation, and brain temperature, all of which are associated with SUD and all of which can influence neurocircuitry and behavior.

Factors Associated with Depressive Symptoms Among Rural Residents from Remote Areas

This study aimed to investigate the risk factors for depressive symptoms among rural residents in Brazil. A representative sample of two hundred eighty-eight volunteers aged from 18 to 65 years was included and determining factors for high BDI-II score were investigated through a multivariate logistic model. Sadness, loss of pleasure, crying, worthlessness and loss of interest in sex are more likely to be observed in females, and risk factors to this high depression score among rural residents were shown to be: female gender, tobacco use, pesticide application, poor self-perceived health and presence of chronic disease. These data contribute to the knowledge of factors determining depressive symptoms among rural residents and may help to expand health policies to improve quality of rural life on these communities and others with similar characteristics.

Medical Conditions Linked to Atherosclerosis Are Associated With Magnified Cortical Thinning in Individuals With Alcohol Use Disorders

AIMS

Magnetic resonance imaging (MRI) studies report widespread cortical thinning in individuals with alcohol use disorder (AUD), but did not consider potential effects of pro-atherogenic conditions such as hypertension, type 2 diabetes mellitus, hepatitis C seropositivity and hyperlipidemia on cortical thickness. The conditions are associated with regional cortical thinning in those without AUD. We predicted that individuals with concurrent AUD and pro-atherogenic conditions demonstrate the greatest regional cortical thinning in areas most vulnerable to decreased perfusion.

METHODS

Treatment-seeking individuals with AUD (n = 126) and healthy controls (CON; n = 49) completed a 1.5 T MRI study. Regional cortical thickness was quantitated via FreeSurfer. Individuals with AUD and pro-atherogenic conditions (Atherogenic+), AUD without pro-atherogenic conditions (Atherogenic-) and CON were compared on regional cortical thickness.

RESULTS

Individuals with AUD showed significant bilateral cortical thinning compared to CON, but Atherogenic+ demonstrated the most widespread and greatest magnitude of regional thinning, while Atherogenic- had reduced thickness primarily in anterior frontal and posterior parietal lobes. Atherogenic+ also showed a thinner cortex than Atherogenic- in lateral orbitofrontal and dorso/dorsolateral frontal cortex, mesial and lateral temporal and inferior parietal regions.

CONCLUSIONS

Our results demonstrate significant bilateral cortical thinning in individuals with AUD relative to CON, but the distribution and magnitude were influenced by comorbid pro-atherogenic conditions. The magnitude of cortical thinning in Atherogenic+ strongly corresponded to cortical watershed areas susceptible to decreased perfusion, which may result in morphometric abnormalities. The findings indicate that pro-atherogenic conditions may contribute to cortical thinning in those seeking treatment for AUD.

Sex/gender differences in brain function and structure in alcohol use: A narrative review of neuroimaging findings over the last 10 years

Over the last 10 years, rates of alcohol use disorder (AUD) have increased in women by 84% relative to a 35% increase in men. Rates of alcohol use and high-risk drinking have also increased in women by 16% and 58% relative to a 7% and 16% increase in men, respectively, over the last decade. This robust increase in drinking among women highlights the critical need to identify the underlying neural mechanisms that may contribute to problematic alcohol consumption across sex/gender (SG), especially given that many neuroimaging studies are underpowered to detect main or interactive effects of SG on imaging outcomes. This narrative review aims to explore the recent neuroimaging literature on SG differences in brain function and structure as it pertains to alcohol across positron emission tomography, magnetic resonance imaging, and functional magnetic resonance imaging modalities in humans. Additional work using magnetic resonance spectroscopy, diffusion tensor imaging, and event-related potentials to examine SG differences in AUD will be covered. Overall, current research on the neuroimaging of AUD, alcohol consumption, or risk of AUD is limited, and findings are mixed regarding the effect of SG on neurochemical, structural, and functional mechanisms associated with AUD. We address SG disparities in the neuroimaging of AUD and propose a call to action to include women in brain imaging research. Future studies are crucial to our understanding of the neurobiological underpinnings of AUD across neural systems and the vulnerability for AUD among women and men.

Longitudinal Cortical Thickness Changes in Bipolar Disorder and the Relationship to Genetic Risk, Mania, and Lithium Use

BACKGROUND

Bipolar disorder (BD) is a highly heritable psychiatric disorder characterized by episodes of manic and depressed mood states and associated with cortical brain abnormalities. Although the course of BD is often progressive, longitudinal brain imaging studies are scarce. It remains unknown whether brain abnormalities are static traits of BD or result from pathological changes over time. Moreover, the genetic effect on implicated brain regions remains unknown.

METHODS

Patients with BD and healthy control (HC) subjects underwent structural magnetic resonance imaging at baseline (123 patients, 83 HC subjects) and after 6 years (90 patients, 61 HC subjects). Cortical thickness maps were generated using FreeSurfer. Using linear mixed effects models, we compared longitudinal changes in cortical thickness between patients with BD and HC subjects across the whole brain. We related our findings to genetic risk for BD and tested for effects of demographic and clinical variables.

RESULTS

Patients showed abnormal cortical thinning of temporal cortices and thickness increases in visual/somatosensory brain areas. Thickness increases were related to genetic risk and lithium use. Patients who experienced hypomanic or manic episodes between time points showed abnormal thinning in inferior frontal cortices. Cortical changes did not differ between diagnostic BD subtypes I and II.

CONCLUSIONS

In the largest longitudinal BD study to date, we detected abnormal cortical changes with high anatomical resolution. We delineated regional effects of clinical symptoms, genetic factors, and medication that may explain progressive brain changes in BD. Our study yields important insights into disease mechanisms and suggests that neuroprogression plays a role in BD.

Cerebellar Morphometry and Cognition in the Context of Chronic Alcohol Consumption and Cigarette Smoking

BACKGROUND

Cerebellar atrophy (especially involving the superior-anterior cerebellar vermis) is among the most salient and clinically significant effects of chronic hazardous alcohol consumption on brain structure. Smaller cerebellar volumes are also associated with chronic cigarette smoking. The present study investigated effects of both chronic alcohol consumption and cigarette smoking on cerebellar structure and its relation to performance on select cognitive/behavioral tasks.

METHODS

Using T1-weighted Magnetic Resonance Images (MRIs), the Cerebellar Analysis Tool Kit segmented the cerebellum into bilateral hemispheres and 3 vermis parcels from 4 participant groups: smoking (s) and nonsmoking (ns) abstinent alcohol-dependent treatment seekers (ALC) and controls (CON) (i.e., sALC, nsALC, sCON, and nsCON). Cognitive and behavioral data were also obtained.

RESULTS

We found detrimental effects of chronic drinking on all cerebellar structural measures in ALC participants, with largest reductions seen in vermis areas. Furthermore, both smoking groups had smaller volumes of cerebellar hemispheres but not vermis areas compared to their nonsmoking counterparts. In exploratory analyses, smaller cerebellar volumes were related to lower measures of intelligence. In sCON, but not sALC, greater smoking severity was related to smaller cerebellar volume and smaller superior-anterior vermis area. In sALC, greater abstinence duration was associated with larger cerebellar and superior-anterior vermis areas, suggesting some recovery with abstinence.

CONCLUSIONS

Our results show that both smoking and alcohol status are associated with smaller cerebellar structural measurements, with vermal areas more vulnerable to chronic alcohol consumption and less affected by chronic smoking. These morphometric cerebellar deficits were also associated with lower intelligence and related to duration of abstinence in sALC only.

Brain Structure Alterations in Poly-Drug Use: Reduced Cortical Thickness and White Matter Impairments in Regions Associated With Affective, Cognitive, and Motor Functions

Substance use disorders (SUDs) are defined by obsessive and uncontrolled consumption, which is related to neurobiological changes. Based on previous work, this study investigated potential alterations in brain structure in poly-drug use disordered (PUD) patients in comparison to controls from the normal population. This study involved a sample of 153 right-handed men aged between 18 and 41 years, comprising a clinical group of 78 PUD and a group of 75 healthy controls. Group differences in gray matter (GM) and white matter (WM), as well as cortical thickness (CT), were investigated by means of diffusion tensor imaging using automated fiber quantification (AFQ) and voxel-based morphometry. We observed significant WM impairments in PUD, especially in the bilateral corticospinal tracts and the inferior longitudinal fasciculi. Furthermore, we found reduced CT in the PUD group especially in the left insular and left lateral orbitofrontal cortex. There were no group differences in GM. In addition, PUD exhibited a higher amount of psychiatric symptoms (Brief Symptom Inventory) and impairments in cognitive functions (Wonderlic Personnel Test). In line with previous research, this study revealed substantial impairments in brain structure in the PUD group in areas linked with affective, cognitive, and motor functions. We therefore hypothesize a neurologically informed treatment approach for SUD. Future studies should consequently explore a potential positive neuroplasticity in relation to a better therapeutic outcome.

Associations Between Drinking and Cortical Thickness in Younger Adult Drinkers: Findings From the Human Connectome Project

BACKGROUND

Previous neuroimaging studies examining relations between alcohol misuse and cortical thickness have revealed that increased drinking quantity and alcohol-related problems are associated with thinner cortex. Although conflicting regional effects are often observed, associations are generally localized to frontal regions (e.g., dorsolateral prefrontal cortex [DLPFC], inferior frontal gyrus [IFG], and anterior cingulate cortex). Inconsistent findings may be attributed to methodological differences, modest sample sizes, and limited consideration of sex differences.

METHODS

This study examined neuroanatomical correlates of drinking quantity and heavy episodic drinking in a large sample of younger adults (N = 706; Mage  = 28.8; 51% female) using magnetic resonance imaging data from the Human Connectome Project. Exploratory analyses examined neuroanatomical correlates of executive function (flanker task) and working memory (list sorting).

RESULTS

Hierarchical linear regression models (controlling for age, sex, education, income, smoking, drug use, twin status, and intracranial volume) revealed significant inverse associations between drinks in past week and frequency of heavy drinking and cortical thickness in a majority of regions examined. The largest effect sizes were found for frontal regions (DLPFC, IFG, and the precentral gyrus). Follow-up regression models revealed that the left DLPFC was uniquely associated with both drinking variables. Sex differences were also observed, with significant effects largely specific to men.

CONCLUSIONS

This study adds to the understanding of brain correlates of alcohol use in a large, gender-balanced sample of younger adults. Although the cross-sectional methodology precludes causal inferences, these findings provide a foundation for rigorous hypothesis testing in future longitudinal investigations.

Association Between Reduced Brain Glucose Metabolism and Cortical Thickness in Alcoholics: Evidence of Neurotoxicity

BACKGROUND

Excessive alcohol consumption is associated with reduced cortical thickness (CT) and lower cerebral metabolic rate of glucose (CMRGlu), but the correlation between these 2 measures has not been investigated.

METHODS

We tested the association between CT and cerebral CMRGlu in 19 participants with alcohol use disorder (AUD) and 20 healthy controls. Participants underwent 2-Deoxy-2-[18F]fluoroglucose positron emission tomography to map CMRGlu and magnetic resonance imaging to assess CT.

RESULTS

Although performance accuracy on a broad range of cognitive domains did not differ significantly between AUD and HC, AUD had widespread decreases in CT and CMRGlu. CMRGlu, normalized to cerebellum (rCMRGlu), showed significant correlation with CT across participants. Although there were large group differences in CMRGlu (>17%) and CT (>6%) in medial orbitofrontal and BA 47, the superior parietal cortex showed large reductions in CMRGlu (~17%) and minimal CT differences (~2.2%). Though total lifetime alcohol (TLA) was associated with CT and rCMRGlu, the causal mediation analysis revealed significant direct effects of TLA on rCMRGlu but not on CT, and there were no significant mediation effects of TLA, CT, and rCMRGlu.

CONCLUSIONS

The significant correlation between decrements in CT and CMRGlu across AUD participants is suggestive of alcohol-induced neurotoxicity, whereas the findings that the most metabolically affected regions in AUD had minimal atrophy and vice versa indicates that changes in CT and CMRGlu reflect distinct responses to alcohol across brain regions.

Region-Specific Changes of Insular Cortical Thickness in Heavy Smokers

Insula plays an essential role in maintaining the addiction to cigarette smoking and smoking-related alterations on the insular volume and density have been reported in smokers. However, less is known about the effects of chronic cigarette smoking on the insular cortical thickness. In this study, we explored the region-specific changes of insular cortical thickness in heavy smokers and their relations with smoking-related variables. 37 heavy smokers (29 males, mean age 47.19 ± 7.22 years) and 37 non-smoking healthy controls (29 males, mean age 46.95 ± 8.45 years) participated in the study. Subregional insular cortical thickness was evaluated and compared between the two groups. Correlation analysis was performed to investigate relationships between the insular cortical thickness and clinical characteristics in heavy smokers. There was no statistical difference on the cortical thickness in the left insula (p = 0.536) between the two groups while heavy smokers had a slightly thinner cortical thickness in the right insula (p = 0.048). In addition, heavy smokers showed a greater cortical thinning in the anterior (p = 0.0084) and superior (p = 0.0054) segment of the circular sulcus of the right insula as well as the inferior (p = 0.012) segment of the circular sulcus of the left insula. Moreover, the cortical thickness of the superior segment of the circular sulcus of the left insula was correlated negatively with nicotine severity (r = −0.423; p = 0.009) and the longer cigarette exposure was associated with the cortical thinning in the long insular gyrus and central sulcus of the right insula (r = −0.475; p = 0.003). Our findings indicate that chronic cigarette use is associated with region-specific insular thinning, which has the potential to improve our understanding of the specific roles of insular subregions in nicotine addiction.

Grey matter structural differences in alcohol-dependent individuals with and without comorbid depression/anxiety-an MRI study

Although depression and anxiety disorders are common comorbid conditions in alcohol dependence, few structural brain imaging studies have compared alcohol-dependent subjects with and without such comorbidity. In the current study, brain scans of 35 alcohol-dependent with and 40 individuals without diagnosis of a comorbid ICD-10 depressive or anxiety disorder receiving detoxification inpatient treatment were evaluated. Thickness and volumes of automatically segmented neuroanatomical structures were measured in FreeSurfer. Furthermore, associations of brain structure with biological markers and clinical severity markers of alcohol dependence were assessed. Despite comparable addiction severity, the non-comorbid group had evidence of higher cytotoxic effects of alcohol use on hepatic and haematological markers, and showed significantly smaller volumes of total cerebral, and cerebellar grey matter. Similarly, they showed unexpected smaller hippocampal and nucleus accumbens volumes, and thinner frontal, temporal and occipital cortices. Smaller brain volumes correlated with increased markers of hepatic and haematological dysfunction, and with longer duration of alcohol dependence in the non-comorbid group. Evidence of higher biomarkers of alcohol use may be indicative of more severe alcohol dependence or higher vulnerability to ethanol toxicity in this group. Furthermore, psychopathology-related drug treatment, which occurred in 53% of the comorbid group over the recent years, or tissue inflammation may have a moderate effect on the grade of cerebral atrophy in alcohol-dependent patients. Longitudinal studies are needed to investigate this issue more fully.

Pulcinelli R, Bandiera S, Caletti G, Bitencourt PER, Quincozes-Santos A, Gomez R. Combined Exposure to Alcohol and Tobacco Smoke Changes Oxidative, Inflammatory, and Neurotrophic Parameters in Different Areas of the Brains of Rats

Devastating effects of exposure to alcohol and tobacco smoke on health are extensively reported in the literature. However, few studies have attempted to elucidate the consequences of their combined use on the central nervous system. Here we studied the effect of this combined use on some oxidative, inflammatory, and neurotrophic parameters in the hippocampus, striatum, and frontal cortex of rats. Adult Wistar rats were allocated into control (CT), alcohol (AL), tobacco smoke (TB), or combined (ALTB) groups. Rats were exposed to environmental air (CT and AL groups) or to the smoke from six cigarettes (TB and ALTB groups) immediately after tap water (CT and TB) or 2 g of alcohol/kg (AL and ALTB) oral gavage administration, twice a day, for 4 weeks. On day 28, rats were euthanized and areas of the brain were dissected to evaluate some cellular redox parameters, pro-inflammatory cytokine levels, and brain-derived neurotrophic factor (BDNF) levels. A one-way analysis of variance showed that the ALTB combined treatment significantly increased oxidative stress levels in the hippocampus. ALTB also increased interleukin-1β levels in the striatum and frontal cortex and tumoral necrosis factor-α levels in the frontal cortex compared with those of AL, TB, and CT rats. Combined treatment also decreased the BDNF levels in the frontal cortex of rats. Oxidative damage was found, more importantly, in the hippocampus, and inflammatory parameters were extended to all areas of the brain that were studied. Our results showed an interaction between alcohol and tobacco smoke according to the area of the brain, suggesting an additional risk of neural damage in alcoholics who smoke.

Body mass index and craving predict 24-month hospital readmissions of alcohol-dependent in-patients following withdrawal

OBJECTIVE

Addictive alcohol drinking, craving, and overeating share common etiopathological mechanisms. We investigated whether body mass index (BMI) and craving predict outcome of alcohol-dependent in-patients.

METHOD

The prospective study included 101 male and 72 female early-abstinent alcohol-dependent in-patients. Craving was quantified by Obsessive-Compulsive Drinking Scale (OCDS) scores. We documented alcohol-related readmissions over 24 months.

RESULTS

In males, a higher BMI was associated with alcohol-related hospital readmission (median 26.1 vs. 23.1 kg/m², P = .007) and correlated with more (ρ = 0.286, P = .004) and earlier readmissions (ρ = -0.256, P = .010). These associations were stronger in the subgroup of active smokers (n = 79; median 25.9 vs. 22.3 kg/m², P = .005; ρ = 0.350, P = .002; ρ = -0.340, P = .002). BMI did not significantly predict outcome in females. Males with at least one readmission reported higher OCDS scores than those without (OCDS-total, OCDS-obsessive, OCDS-compulsive, P < .040), and the OCDS scores correlated with more readmissions (males: OCDS-total, OCDS-obsessive, OCDS-compulsive, ρ > 0.244, P < .014; females: OCDS-compulsive, ρ = 0.341, P = .003) and fewer days to first readmission (males: OCDS-total, OCDS-compulsive, ρ < -0.195, P < .050; females: OCDS-compulsive, ρ = -0.335, P = .004). The OCDS scores explained 9 to 19% of the relationship between BMI and outcome in males.

CONCLUSION

BMI and craving are easily accessible outcome predictors of alcohol-related readmission following in-patient withdrawal treatment. They might be used to individualize relapse prevention in the future.

Signatures of alcohol use in the structure and neurochemistry of insular cortex: a correlational study

RATIONALE

Insular cortex supports the representation of motivational feelings through the integration of interoceptive information concerning bodily physiology. Compromised insular integrity is implicated in alcohol and drug use disorders. Alcohol-associated insular dysfunction may arise through aberrant glutamatergic neurotransmission associated with selective neuronal death and atrophy.

OBJECTIVE

In a sample of alcohol users, we combined magnetic resonance spectroscopy (MRS) with voxel and surface-based morphometry (VBM, SBM) to test the hypothesis that the neurochemical and structural properties of the insula relate to alcohol use.

METHODS

Twenty-three healthy individuals were characterized by measures of alcohol use and subjective craving. Right mid-insula glutamate/glutamine (Glx) and total N-acetylaspartate/N-acetyl-aspartylglutamate (TNAA) concentrations were measured using MRS. Right insular structure was quantified using VBM and SBM parameters. We tested for predictive associations between these neuroimaging and behavioral/psychometric measures using Bayesian statistics.

RESULTS

Reduced insular Glx concentration was associated with increased alcohol compulsions and, to a lesser extent, with greater alcohol use severity. Anecdotal evidence for a negative relationship between alcohol use severity and levels of insular gyrification was also observed.

CONCLUSIONS

This study is, to date, the first characterization of the neurochemical and morphological integrity of insular cortex in alcohol users. Our data seem to reveal a negative relationship between alcohol use and the neurochemical and structural integrity of the insula, a critical substrate for motivational behavior. These neurobiological characteristics might contribute to loss of control toward compulsive drinking with prolonged and excessive alcohol use.

Cigarette smoking is associated with cortical thinning in anterior frontal regions, insula and regions showing atrophy in early Alzheimer's Disease

BACKGROUND

Magnetic resonance imaging studies of cigarette smoking-related effects on human brain structure primarily focused on cortical volumes. Much less is known about the effects of smoking on cortical thickness. Smokers and Non-smokers were compared on regional cortical thickness. We predicted smokers would demonstrate greater age-related thinning localized to anterior frontal regions that serve as nodes for the executive, salience, and emotional regulation networks (ESER regions) and those demonstrating significant atrophy in early Alzheimer's Disease (AD regions).

METHODS

Non-smokers (n = 41) and smokers (n = 41), 22-70 years of age, completed a 4 T MRI study. Regional cortical thickness was quantitated via FreeSurfer. In smokers, associations between smoking severity, decision-making, impulsivity, and regional cortical thickness were examined.

RESULTS

Smokers demonstrated cortical thinning in the medial and lateral OFC, insula, entorhinal, fusiform, middle temporal, and Composite AD regions. In Smokers, greater pack-years were associated with thinner lateral OFC, middle temporal, inferior parietal, fusiform, precuneus, and Composite AD regions. In Smokers, poorer decision-making/greater risk taking was related to thinner cortices in caudal ACC, rostral middle frontal and superior frontal gyri, and Composite ESER. Higher self-reported impulsivity was associated with thinner rostral and caudal ACC.

CONCLUSIONS

This study provides additional evidence that cigarette smoking is associated with thinner cortices in regions implicated in the development and maintenance of substance use disorders and in regions demonstrating significant atrophy in early AD. The novel structure-function relationships in Smokers further our understanding of the neurobiological substrates potentially underlying the neuropsychological abnormalities documented in smokers.

Amygdala volume mediates the relationship between externalizing symptoms and daily smoking in adolescence: A prospective study

The current study examined amygdala and orbitofrontal cortex (OFC) volumes as mediators of the relationship between externalizing symptoms and daily smoking in adolescence. Externalizing behaviors are among the most robust predictors of adolescent smoking, and there is emerging evidence that volume reductions in the amygdala and OFC are associated with risk for substance misuse as well as aggressive, impulsive, and disinhibited tendencies. Using a prospective longitudinal design, we recruited 109 adolescents who provided data on brain volume and externalizing behaviors at age 12, and on smoking at age 18. Daily smoking at age 18 (n = 27) was predicted by externalizing behaviors (measured by the self-report Child Behavior Checklist, CBCL) as well as smaller right amygdala volumes. Right amygdala volumes mediated the relationship between externalizing symptoms and later smoking. These findings provide important insight into the neurobiological risk factors associated with adolescent smoking, and, more generally, into factors that may be associated with vulnerability to substance use disorders and related psychopathology.

Pesticide exposure, tobacco use, poor self-perceived health and presence of chronic disease are determinants of depressive symptoms among coffee growers from Southeast Brazil

The lifestyle and other factors associated with the appearance of several health conditions that affect quality of life in rural zone is an issue that has been increasingly explored. Brazil is the largest coffee-producing nation in the world and has been a considerable consumer of pesticides since 2008. The aim of the present study was to investigate factors that could be contributing to the appearance of depressive symptoms in rural workers. Two hundred twenty male volunteers from nine cities in Southeast Brazil completed the Beck Depression Inventory-II (BDI-II) questionnaire about depressive symptoms and provided other information about socio-demographic characteristics and additional confounding factors. The adjusted multivariate logistic analysis demonstrated that pesticide exposure, tobacco use, poor self-perceived health and the presence of chronic disease contribute as risk factors for the appearance of depressive symptoms at a level above ups and downs considered normal in the BDI-II. This survey contributes to the search for solutions to improve quality of life and mental health in the rural living to the extent that social determinants of depression are being investigated.

Brain GABA and Glutamate Concentrations Following Chronic Gabapentin Administration: A Convenience Sample Studied During Early Abstinence From Alcohol

Gabapentin (GBP), a GABA analog that may also affect glutamate (Glu) production, can normalize GABA and Glu tone during early abstinence from alcohol, effectively treating withdrawal symptoms and facilitating recovery. Using in vivo magnetic resonance spectroscopy, we tested the degree to which daily GBP alters regional brain GABA and Glu levels in short-term abstinent alcohol-dependent individuals. Regional metabolite levels were compared between 13 recently abstinent alcohol-dependent individuals who had received daily GBP for at least 1 week (GBP+) and 25 matched alcohol-dependent individuals who had not received GBP (GBP-). Magnetic resonance spectra from up to five different brain regions were analyzed to yield absolute GABA and Glu concentrations. GABA and Glu concentrations in the parieto-occipital cortex were not different between GBP- and GBP+. Glu levels in anterior cingulate cortex, dorsolateral prefrontal cortex, and basal ganglia did not differ between GBP- and GBP+. However, in a subgroup of individuals matched on age, sex, and abstinence duration, GBP+ had markedly lower Glu in the frontal white matter (WM) than GBP-, comparable to concentrations found in light/non-drinking controls. Furthermore, lower frontal WM Glu in GBP+ correlated with a higher daily GBP dose. Daily GBP treatment at an average of 1,600 mg/day for at least 1 week was not associated with altered cortical GABA and Glu concentrations during short-term abstinence from alcohol, but with lower Glu in frontal WM. GBP for the treatment of alcohol dependence may work through reducing Glu in WM rather than increasing cortical GABA.

Effect of tobacco smoking on frontal cortical thickness development: A longitudinal study in a mixed cohort of ADHD-affected and -unaffected youth

Smoking rates are particularly high during adolescence and young adulthood, when the brain is still undergoing significant developmental changes. Cross-sectional studies have revealed altered brain structure in smokers, such as thinner frontal cortical areas. Attention-deficit/hyperactivity disorder (ADHD) increases the risk of becoming nicotine-dependent, and has also been associated with abnormalities in frontal gray matter structure. The present study examines the relationships between smoking, cortical thickness and ADHD symptoms in a longitudinal design that compares adolescent and young adult smokers (n=44; 35 ADHD-affected) and non-smokers (n=45; 32 ADHD-affected) on frontal cortical thickness. Average frontal cortical thickness was estimated through structural magnetic resonance imaging (MRI) at two time points (mean ages 17.7 and 21.1 years), on average 3.4 years apart. Smokers had a 2.6% thinner frontal cortex than non-smokers and this difference was not explained by ADHD or other confounding factors. The rate of cortical thinning across the 3.4-year MRI measurement interval was similar in the total group of smokers compared to non-smokers. However, speeded thinning did occur in smokers who had started regular smoking more recently, in between the two measurements. These novel regular smokers did not differ significantly from the non-smokers at baseline. This suggests that the thinner frontal cortex was not a predisposing factor but rather a consequence of smoking. Although smokers had more ADHD symptoms overall, smoking did not influence the developmental course of ADHD symptoms.

Effects of abstinence and chronic cigarette smoking on white matter microstructure in alcohol dependence: Diffusion tensor imaging at 4T

BACKGROUND

We previously reported widespread microstructural deficits of brain white matter in alcohol-dependent individuals (ALC) compared to light drinkers in a small 1.5T diffusion tensor imaging study employing tract-based spatial statistics. Using a larger dataset acquired at 4T, the present study is an extension that investigated the effects of alcohol consumption, abstinence from alcohol, and comorbid cigarette smoking on white matter microstructure.

METHODS

Tract-based spatial statistics were performed on 20 1-week-abstinent ALC, 52 1-month-abstinent ALC, and 30 controls. Regional measures of fractional anisotropy (FA) and mean diffusivity (MD) in the significant clusters were compared by Analysis of Covariance. The metrics were correlated with substance use history and behavioral measures.

RESULTS

1-week-abstinent ALC showed lower FA than controls in the corpus callosum, right cingulum, external capsule, and hippocampus. At 1 month of abstinence, only the FA in the body of the corpus callosum of ALC remained significantly different from controls. Some regional FA deficits correlated with more severe measures of drinking and smoking histories but only weakly with mood and impulsivity measures.

CONCLUSION

White matter microstructure is abnormal during early abstinence in alcohol dependent treatment seekers and recovers into the normal range within about four weeks. The compromised white matter was related to substance use severity, mood, and impulsivity. Our findings suggest that ALC may benefit from interventions that facilitate normalization of DTI metrics to maintain abstinence, via smoking cessation, cognitive-based therapy, and perhaps pharmacology to support remyelination.

Structural Neuroimaging in Polysubstance Users

The simultaneous and/or concurrent use of licit and illicit substances (polysubstance use, PSU) is most common today. Structural magnetic resonance imaging (MRI) has been applied extensively to study individuals ostensibly using a single substance. These studies have produced a picture of regional gray matter and white matter alterations with each substance or class of substances. Very few studies measured regional brain morphometry in today's polysubstance users. This limited data suggest morphometric alterations with PSU that are not simply additive but often different from those of monosubstance users. Specifically, subcortical volume enlargements are observed that may be tied to mechanisms that also oppose volume reductions in cortical brain regions, thereby underestimating actual cortical atrophy. The complex actions of polysubstance use on brain structure and function need greater scrutiny with strong methodological approaches to inform more efficient treatment of polysubstance users.

Effects of cigarette smoking on cortical thickness in major depressive disorder

Findings of surface-based morphometry studies in major depressive disorder (MDD) are still inconsistent. Given that cigarette smoking is highly prevalent in MDD and has documented negative effects on the brain, it is possible that some of the inconsistencies may be partly explained by cigarette use. The aim of the current study was to examine the influence of cigarette smoking on brain structure in MDD. 50 MDD patients (25 smokers and 25 non-smokers) and 22 age, education, gender and BMI matched non-smoker healthy controls underwent structural magnetic resonance imaging. Thickness and area of the cortex were measured using surface-based morphometry implemented with Freesurfer (v5.3.0). The non-smoker MDD patients had significantly increased cortical thickness, including in the left temporal cortex (p < 0.001), right insular cortex (p = 0.033) and left pre- and postcentral gyrus (p = 0.045), compared to healthy controls. We also found decreased cortical thickness in MDD patients who smoked compared to non-smoking patients in regions that overlapped with the regions found to be increased in non-smoking patients in comparison to controls. Non-smoker MDD patients had increased surface area in the right lateral occipital cortex (p = 0.009). We did not find any region where cortical thickness or surface area significantly differed between controls and either smoker MDD patients or all MDD patients. The findings of the current study suggest that cigarette smoking is associated with cortical thinning in regions found to be increased in patients with MDD. However, these results should be considered preliminary due to methodological limitations.

Severity of alcohol dependence is negatively related to hypothalamic and prefrontal cortical gray matter density in heavy drinking smokers

BACKGROUND

While research has examined brain structure in individuals who use alcohol or nicotine, heavy drinking smokers comprise a unique subpopulation of substance users for whom less is known about the relationship between alcohol or nicotine use and structural brain abnormalities.

OBJECTIVES

The present study examined gray matter morphometry in a sample of 39 heavy drinking smokers (24 males, 15 females) in relation to alcohol and nicotine dependence and quantity of use.

METHODS

Traditional voxel-based morphometry techniques were employed for preprocessing of imaging data. One multiple regression analysis for alcohol and nicotine dependence severity and another for alcohol and nicotine quantity of use were conducted, while controlling for age, gender, and total intracranial volume (ICV).

RESULTS

Alcohol dependence severity was significantly negatively associated with gray matter density in the hypothalamus (p < 0.001, uncorrected) and the right superior frontal gyrus (p < 0.001, uncorrected), while controlling for nicotine dependence severity, age, gender, and ICV. There were no significant relationships observed with respect to nicotine dependence severity, the quantity of alcohol use, or the quantity of nicotine use variables and gray matter density.

CONCLUSIONS

These findings suggest that within heavy drinking smokers, alcohol dependence severity is significantly related to alterations in brain structure, while this effect is not seen for the quantity of alcohol or nicotine use, or severity of nicotine dependence. The current findings help clarify the contribution of alcohol and nicotine effects on brain structure, which could aid in understanding their neurocognitive consequences in heavy drinking smokers.

Psychiatric, Demographic, and Brain Morphological Predictors of Relapse After Treatment for an Alcohol Use Disorder

BACKGROUND

Relapse in alcohol use disorders (AUD) is related to a complex interplay among multiple biological, psychiatric, psychological, and psychosocial factors, which may change dynamically during and after treatment. At treatment entry for AUD, morphological abnormalities in anterior frontal regions and the insula have been observed in those who ultimately relapse following treatment. The goal of this study was to determine whether anterior frontal and insula measures of brain thickness, surface area, and volume predict posttreatment drinking status (i.e., relapser or abstainer) over an extended period after outpatient treatment for AUD, while concurrently considering common psychiatric, psychological, and psychosocial factors previously associated with relapse.

METHODS

Alcohol-dependent individuals (n = 129) were followed for 18 months after treatment to determine posttreatment drinking status (abstainers [n = 47] or relapsers [n = 82]). Brain morphometrics were derived from FreeSurfer. Receiver operating characteristic (ROC) curve analysis was used to identify the regional brain thickness, surface area, and volume (all scaled to intracranial volume), demographic, psychiatric, other substance use (e.g., cigarette smoking), and alcohol consumption variables, obtained at entry into treatment, that best predicted posttreatment drinking status. Survival analyses determined variables that were related to duration of abstinence after treatment.

RESULTS

ROC analyses indicated that mood disorders, education, and volumes of the right caudal anterior cingulate cortex (ACC), right rostral ACC, and total right frontal gray matter were significant predictors of posttreatment drinking status. Among relapsers, survival analyses showed smokers and individuals with a comorbid medical condition relapsed earlier after treatment. Additionally, a greater frequency of smokers relapsed within 6 months of AUD treatment.

CONCLUSIONS

Results reinforce that relapse in AUD is a function of multiple biological, psychiatric, psychological, and psychosocial factors. Effective treatment of depressive disorders and cigarette smoking concurrent with AUD-focused interventions may promote better treatment outcomes.

Cortical thickness, volume and surface area in patients with bipolar disorder types I and II

BACKGROUND

Bipolar disorder (BD) is a common chronic psychiatric disorder mainly characterized by episodes of mania, hypomania and depression. The disorder is associated with cognitive impairments and structural brain abnormalities, such as lower cortical volumes in primarily frontal brain regions than healthy controls. Although bipolar disorder types I (BDI) and II (BDII) exhibit different symptoms and severity, previous studies have focused on BDI. Furthermore, the most frequently investigated measure in this population is cortical volume. The aim of our study was to investigate abnormalities in patients with BDI and BDII by simultaneously analyzing cortical volume, thickness and surface area, which yields more information about disease- and symptom-related neurobiology.

METHODS

We used MRI to measure cortical volume, thickness and area in patients with BDI and BDII as well as in healthy controls. The large study cohort enabled us to adjust for important confounding factors.

RESULTS

We included 81 patients with BDI, 59 with BDII and 85 controls in our analyses. Cortical volume, thickness and surface area abnormalities were present in frontal, temporal and medial occipital regions in patients with BD. Lithium and antiepileptic drug use had an effect on the observed differences in medial occipital regions. Patients with the subtypes BDI and BDII displayed common cortical abnormalities, such as lower volume, thickness and surface area than healthy controls in frontal brain regions but differed in temporal and medial prefrontal regions, where only those with BDI had abnormally low cortical volume and thickness.

LIMITATIONS

The group differences can be explained by progressive changes, but also by premorbid conditions. They could also have been influenced by unknown factors, such as social, environmental or genetic factors.

CONCLUSION

Our findings suggest diagnosis-related neurobiological differences between the BD subtypes, which could explain distinct symptoms and point to potential biomarkers that could inform the subtype diagnosis of BD.

Effects of cigarette smoking and alcohol use on neurocognition and BDNF levels in a Chinese population

OBJECTIVE

Few studies have examined the potential interactive effect of both smoking and drinking on cognition. Brain-derived neurotrophic factor (BDNF) plays a critical role in cognition. This is the first study to examine the neurocognitive consequences of cigarette smoking combined with chronic alcohol consumption and their relationship to serum BDNF levels in a Chinese Han population.

MATERIALS AND METHODS

We recruited 191 healthy male subjects, including 47 isolated smokers, 31 isolated chronic alcohol users, 58 combined smokers and chronic alcohol users, and 55 non-smokers and non-alcohol users. We then compared the repeatable battery for the assessment of neuropsychological status (RBANS) scores and serum BDNF levels in these four groups.

RESULTS

When compared to the non-smoking + non-alcohol-using group, the smoking group performed worse on immediate memory, attention, language, and RBANS total score. There were no significant differences in the RBANS scores between the alcohol-using group and non-smoking + non-alcohol-using group, or between the smoking group and smoking + alcohol-using group. We did not find an association between BDNF and smoking or drinking status or between BDNF and cognitive performance. In the smoking group, there was a significant correlation between BDNF and carbon monoxide concentration, and between BDNF and the Fagerstrom Test for Nicotine Dependence (FTND) total score.

CONCLUSIONS

Our results suggest that smoking is associated with cognitive decline, but not with BDNF levels in a normal population. However, smoking severity is positively associated with BDNF levels. Concomitant alcohol use does not worsen the cognitive decline caused by smoking.

The Synergistic Impact of Excessive Alcohol Drinking and Cigarette Smoking upon Prospective Memory

The independent use of excessive amounts of alcohol or persistent cigarette smoking have been found to have a deleterious impact upon Prospective Memory (PM: remembering future intentions and activities), although to date, the effect of their concurrent use upon PM is yet to be explored. The present study investigated the impact of the concurrent use of drinking excessive amounts of alcohol and smoking cigarettes (a "Polydrug" group) in comparison to the combined effect of the single use of these substances upon PM. The study adopted a single factorial independent groups design. The Cambridge Prospective Memory Test (CAMPROMPT) is a test of both time-based and event-based PM and was used here to measure PM. The CAMPROMPT was administered to 125 adults; an excessive alcohol user group (n = 40), a group of smokers who drink very little alcohol (n = 20), a combined user group (the "Polydrug" group) who drink excessively and smoke cigarettes (n = 40) and a non-drinker/low alcohol consumption control group (n = 25). The main findings revealed that the Polydrug users recalled significantly fewer time-based PM tasks than both excessive alcohol users p < 0.001 and smokers p = 0.013. Polydrug users (mean = 11.47) also remembered significantly fewer event-based PM tasks than excessive alcohol users p < 0.001 and smokers p = 0.013. With regards to the main aim of the study, the polydrug users exhibited significantly greater impaired time-based PM than the combined effect of single excessive alcohol users and cigarette smokers p = 0.033. However, no difference was observed between polydrug users and the combined effect of single excessive alcohol users and cigarette smokers in event-based PM p = 0.757. These results provide evidence that concurrent (polydrug) use of these two substances has a synergistic effect in terms of deficits upon time-based PM. The observation that combined excessive drinking and cigarette smoking leads to a greater impairment in time-based PM may be of paramount importance, given the key role PM plays in everyday independent living.

Manic episodes are related to changes in frontal cortex: a longitudinal neuroimaging study of bipolar disorder 1

Higher numbers of manic episodes in bipolar patients has, in cross-sectional studies, been associated with less grey matter volume in prefrontal brain areas. Longitudinal studies are needed to determine if manic episodes set off progressive cortical changes, or if the association is better explained by premorbid brain conditions that increase risk for mania. We followed patients with bipolar disorder type 1 for 6 years. Structural brain magnetic resonance imaging scans were performed at baseline and follow-up. We compared patients who had at least one manic episode between baseline and follow-up (Mania group, n = 13) with those who had no manic episodes (No-Mania group, n = 18). We used measures of cortical volume, thickness, and area to assess grey matter changes between baseline and follow-up. We found significantly decreased frontal cortical volume (dorsolateral prefrontal and inferior frontal cortex) in the Mania group, but no volume changes in the No-Mania group. Our results indicate that volume decrease in frontal brain regions can be attributed to the incidence of manic episodes.

Cigarette Smoking and Risk of Alcohol Use Relapse Among Adults in Recovery from Alcohol Use Disorders

BACKGROUND

Individuals in recovery from alcohol use disorders (AUDs) frequently continue to smoke cigarettes. The purpose of this study was to examine the relationship between cigarette smoking status and risk of AUD relapse in adults with remitted AUDs among adults in the United States.

METHODS

Data were drawn from Wave 1 (2001 to 2002) and Wave 2 (2004 to 2005) of the National Epidemiologic Survey on Alcohol and Related Conditions. Analyses included the subsample of respondents who completed both waves of data collection reported a history of alcohol abuse and/or dependence prior to Wave 1 (N = 9,134). Relationships between Wave 1 cigarette smoking status (nonsmoker, daily cigarette smoker, and nondaily cigarette smoker) and Wave 2 alcohol use, abuse, and dependence were examined using logistic regression analyses. Analyses were adjusted for Wave 1 demographics; mood, anxiety, and substance use disorders; nicotine dependence; and AUD severity.

RESULTS

Both daily and nondaily cigarette smoking at Wave 1 were significantly associated with a lower likelihood of alcohol use and a greater likelihood of alcohol abuse and dependence at Wave 2 compared to Wave 1 nonsmoking. These relationships remained significant after adjusting for demographics, psychiatric disorders, substance use disorders, AUD severity, and nicotine dependence.

CONCLUSIONS

Among adults with remitted AUDs, daily and nondaily use of cigarettes was associated with significantly decreased likelihood of alcohol use and increased likelihood of alcohol abuse and alcohol dependence 3 years later. Concurrent treatment of cigarette smoking when treating AUDs may help improve long-term alcohol outcomes and reduce the negative consequences of both substances.

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.

Advances in nicotine research in Addiction Biology

The aim of Addiction Biology is to advance our understanding of the action of drugs of abuse and addictive processes via the publication of high-impact clinical and pre-clinical findings resulting from behavioral, molecular, genetic, biochemical, neurobiological and pharmacological research. As of 2013, Addiction Biology is ranked number 1 in the category of Substance Abuse journals (SCI). Occasionally, Addiction Biology likes to highlight via review important findings focused on a particular topic and recently published in the journal. The current review summarizes a number of key publications from Addiction Biology that have contributed to the current knowledge of nicotine research, comprising a wide spectrum of approaches, both clinical and pre-clinical, at the cellular, molecular, systems and behavioral levels. A number of findings from human studies have identified, using imaging techniques, alterations in common brain circuits, as well as morphological and network activity changes, associated with tobacco use. Furthermore, both clinical and pre-clinical studies have characterized a number of mechanistic targets critical to understanding the effects of nicotine and tobacco addiction. Together, these findings will undoubtedly drive future studies examining the dramatic impact of tobacco use and the development of treatments to counter nicotine dependence.

Comparison of Regional Brain Perfusion Levels in Chronically Smoking and Non-Smoking Adults

Chronic cigarette smoking is associated with numerous abnormalities in brain neurobiology, but few studies specifically investigated the chronic effects of smoking (compared to the acute effects of smoking, nicotine administration, or nicotine withdrawal) on cerebral perfusion (i.e., blood flow). Predominately middle-aged male (47 ± 11 years of age) smokers (n = 34) and non-smokers (n = 27) were compared on regional cortical perfusion measured by continuous arterial spin labeling magnetic resonance studies at 4 Tesla. Smokers showed significantly lower perfusion than non-smokers in the bilateral medial and lateral orbitofrontal cortices, bilateral inferior parietal lobules, bilateral superior temporal gyri, left posterior cingulate, right isthmus of cingulate, and right supramarginal gyrus. Greater lifetime duration of smoking (adjusted for age) was related to lower perfusion in multiple brain regions. The results indicated smokers showed significant perfusion deficits in anterior cortical regions implicated in the development, progression, and maintenance of all addictive disorders. Smokers concurrently demonstrated reduced blood flow in posterior brain regions that show morphological and metabolic aberrations as well as elevated beta amyloid deposition demonstrated by those with early stage Alzheimer disease. The findings provide additional novel evidence of the adverse effects of cigarette smoking on the human brain.

Cigarette smoking is associated with thinner cingulate and insular cortices in patients with severe mental illness

BACKGROUND

Magnetic resonance imaging (MRI) studies show reduced cortical thickness in patients with schizophrenia and bipolar disorder. These subtle brain abnormalities may provide insight into illness mechanisms. However, environmental and lifestyle-related factors, such as cigarette smoking, may contribute to brain structure changes. Cigarette smoking is highly prevalent in patients with severe mental illness. In nonpsychiatric samples, smoking has been associated with reduced thickness in the anterior (ACC) and posterior cingulate cortices, the insular cortex (INS), the dorsolateral prefrontal cortex and the orbitofrontal cortex.

METHODS

We examined MRI scans from patients with schizophrenia, other psychotic disorders or bipolar disorder and healthy controls using FreeSurfer.

RESULTS

We included 506 patients (49% smokers) and 237 controls (20% smokers) in our study. We found reduced cortical thickness in the left rostral ACC and the left INS in smoking patients compared with nonsmoking patients, but this difference was not found among healthy controls. No dose-response relationship was found between amount of smoking and cortical thickness in these regions. Among patients, maps of thickness along the whole cortical surface revealed reduced insular thickness but no effects in other regions. Among healthy controls, similar analyses revealed increased age-related cortical thinning in the left occipital lobe among smokers compared with nonsmokers.

LIMITATIONS

The causal direction could not be determined owing to the cross-sectional design and lack of detailed data on smoking addiction and smoking history.

CONCLUSION

The effect of cigarette smoking should be considered in MRI studies of patients with severe mental illness.

Cigarette smoking and thinning of the brain's cortex

Cigarette smoking is associated with cognitive decline and dementia, but the extent of the association between smoking and structural brain changes remains unclear. Importantly, it is unknown whether smoking-related brain changes are reversible after smoking cessation. We analyzed data on 504 subjects with recall of lifetime smoking data and a structural brain magnetic resonance imaging at age 73 years from which measures of cortical thickness were extracted. Multiple regression analyses were performed controlling for gender and exact age at scanning. To determine dose-response relationships, the association between smoking pack-years and cortical thickness was tested and then repeated, while controlling for a comprehensive list of covariates including, among others, cognitive ability before starting smoking. Further, we tested associations between cortical thickness and number of years since last cigarette, while controlling for lifetime smoking. There was a diffuse dose-dependent negative association between smoking and cortical thickness. Some negative dose-dependent cortical associations persisted after controlling for all covariates. Accounting for total amount of lifetime smoking, the cortex of subjects who stopped smoking seems to have partially recovered for each year without smoking. However, it took ~25 years for complete cortical recovery in affected areas for those at the mean pack-years value in this sample. As the cortex thins with normal aging, our data suggest that smoking is associated with diffuse accelerated cortical thinning, a biomarker of cognitive decline in adults. Although partial recovery appears possible, it can be a long process.

Alcohol use disorder with and without stimulant use: brain morphometry and its associations with cigarette smoking, cognition, and inhibitory control

OBJECTIVE

Little is known about the effects of polysubstance use and cigarette smoking on brain morphometry. This study examined neocortical brain morphometric differences between abstinent polysubstance dependent and alcohol-only dependent treatment seekers (ALC) as well as light drinking controls (CON), the associations of cigarette smoking in these polysubstance users (PSU), and morphometric relationships to cognition and inhibitory control.

METHODS

All participants completed extensive neuropsychological assessments and 4 Tesla brain magnetic resonance imaging. PSU and ALC were abstinent for one month at the time of study. Parcellated morphological data (volume, surface area, thickness) were obtained with FreeSurfer methodology for the following bilateral components: dorso-prefrontal cortex (DPFC), anterior cingulate cortex (ACC), orbitofrontal cortex (OFC), and insula. Regional group differences were examined and structural data correlated with domains of cognition and inhibitory control.

RESULTS

PSU had significantly smaller left OFC volume and surface area and trends to smaller right DPFC volume and surface area compared to CON; PSU did not differ significantly from ALC on these measures. PSU, however, had significantly thinner right ACC than ALC. Smoking PSU had significantly larger right OFC surface area than non-smoking PSU. No significant relationships between morphometry and quantity/frequency of substance use, alcohol use, or age of onset of heavy drinking were observed. PSU exhibited distinct relationships between brain structure and processing speed, cognitive efficiency, working memory and inhibitory control that were not observed in ALC or CON.

CONCLUSION

Polysubstance users have unique morphometric abnormalities and structure-function relationships when compared to individuals dependent only on alcohol and light drinking controls. Chronic cigarette smoking is associated with structural brain irregularities in polysubstance users. Further elucidation of these distinctive characteristics could help inform the development of targeted and thus potentially more effective treatments in this large but understudied population.