Cortical thickness and trait empathy in patients and people at high risk for alcohol use disorders

Patterns of executive functions and theory of mind in adults with a family history of alcohol use disorder: Combined group and single-case analyses

BACKGROUND

Impairments in executive function and social cognition are highly prevalent in individuals with an alcohol use disorder (AUD). Some studies show that similar difficulties are displayed by individuals with a positive family history of AUD (FH+) compared with individuals with a negative family history (FH-). Yet, no studies have jointly investigated cognitive and affective theory of mind at the behavioral level. Moreover, some studies show preserved executive and socioemotional functioning in FH+ participants. One possible explanation for these divergent results is that FH+ individuals are cognitively heterogeneous. In this study, we examined the frequency and co-occurrence of difficulties in executive function and social cognition among FH+ individuals at the individual level.

METHODS

Sixty FH+ and 60 FH- participants matched on age, sex, and education level were included. They completed tasks assessing executive functions (Stroop, Trail Making Test) and affective and cognitive theory of mind (Movie for the Assessment of Social Cognition). They also completed self-report questionnaires measuring impulsivity, alexithymia, and empathy. Single-case analyses assessed the proportion of FH+ participants with difficulties in executive function and/or theory of mind.

RESULTS

FH+ individuals exhibited difficulties in response inhibition and made more errors during theory of mind processing, indicating an absence of mental state representation, compared with FH- individuals. In the FH+ sample, 53.33% had executive function and/or theory of mind difficulties. Those with lower theory of mind scores reported higher alexithymia and lower empathy on self-report measures.

CONCLUSIONS

FH+ individuals display heterogeneous executive function and theory of mind abilities. Given that they mostly occur independently of one another, executive function and theory of mind difficulties may be distinct vulnerability markers in AUD.

Neuroanatomical correlates of aggressiveness: a case-control voxel- and surface-based morphometric study

Aggression occurs across the population ranging on a symptom continuum. Most previous studies have used magnetic resonance imaging in clinical/forensic samples, which is associated with several confounding factors. The present study examined structural brain characteristics in two healthy samples differing only in their propensity for aggressive behavior. Voxel- and surface-based morphometry (SBM) analyses were performed on 29 male martial artists and 32 age-matched male controls. Martial artists had significantly increased mean gray matter volume in two frontal (left superior frontal gyrus and bilateral anterior cingulate cortex) and one parietal (bilateral posterior cingulate gyrus and precuneus) brain clusters compared to controls (whole brain: p < 0.001, cluster level: family-wise error (FWE)-corrected). SBM analyses revealed a trend for greater gyrification indices in martial artists compared to controls in the left lateral orbital frontal cortex and the left pars orbitalis (whole brain: p < 0.001, cluster level: FWE-corrected). The results indicate brain structural differences between martial artists and controls in frontal and parietal brain areas critical for emotion processing/inhibition of emotions as well as empathic processes. The present study highlights the importance of studying healthy subjects with a propensity for aggressive behavior in future structural MRI research on aggression.

Adaptor protein complex 2 in the orbitofrontal cortex predicts alcohol use disorder

Alcohol use disorder (AUD) is a life-threatening disease characterized by compulsive drinking, cognitive deficits, and social impairment that continue despite negative consequences. The inability of individuals with AUD to regulate drinking may involve functional deficits in cortical areas that normally balance actions that have aspects of both reward and risk. Among these, the orbitofrontal cortex (OFC) is critically involved in goal-directed behavior and is thought to maintain a representation of reward value that guides decision making. In the present study, we analyzed post-mortem OFC brain samples collected from age- and sex-matched control subjects and those with AUD using proteomics, bioinformatics, machine learning, and reverse genetics approaches. Of the 4,500+ total unique proteins identified in the proteomics screen, there were 47 proteins that differed significantly by sex that were enriched in processes regulating extracellular matrix and axonal structure. Gene ontology enrichment analysis revealed that proteins differentially expressed in AUD cases were involved in synaptic and mitochondrial function, as well as transmembrane transporter activity. Alcohol-sensitive OFC proteins also mapped to abnormal social behaviors and social interactions. Machine learning analysis of the post-mortem OFC proteome revealed dysregulation of presynaptic (e.g., AP2A1) and mitochondrial proteins that predicted the occurrence and severity of AUD. Using a reverse genetics approach to validate a target protein, we found that prefrontal Ap2a1 expression significantly correlated with voluntary alcohol drinking in male and female genetically diverse mouse strains. Moreover, recombinant inbred strains that inherited the C57BL/6J allele at the Ap2a1 interval consumed higher amounts of alcohol than those that inherited the DBA/2J allele. Together, these findings highlight the impact of excessive alcohol consumption on the human OFC proteome and identify important cross-species cortical mechanisms and proteins that control drinking in individuals with AUD.

Adaptor protein complex 2 in the orbitofrontal cortex predicts alcohol use disorder

Alcohol use disorder (AUD) is a life-threatening disease characterized by compulsive drinking, cognitive deficits, and social impairment that continue despite negative consequences. The inability of individuals with AUD to regulate drinking may involve functional deficits in cortical areas that normally balance actions that have aspects of both reward and risk. Among these, the orbitofrontal cortex (OFC) is critically involved in goal-directed behavior and is thought to maintain a representation of reward value that guides decision making. In the present study, we analyzed post-mortem OFC brain samples collected from age- and sex-matched control subjects and those with AUD using proteomics, bioinformatics, machine learning, and reverse genetics approaches. Of the 4,500+ total unique proteins identified in the proteomics screen, there were 47 proteins that differed significantly by sex that were enriched in processes regulating extracellular matrix and axonal structure. Gene ontology enrichment analysis revealed that proteins differentially expressed in AUD cases were involved in synaptic and mitochondrial function, as well as transmembrane transporter activity. Alcohol-sensitive OFC proteins also mapped to abnormal social behaviors and social interactions. Machine learning analysis of the post-mortem OFC proteome revealed dysregulation of presynaptic (e.g., AP2A1) and mitochondrial proteins that predicted the occurrence and severity of AUD. Using a reverse genetics approach to validate a target protein, we found that prefrontal Ap2a1 expression significantly correlated with voluntary alcohol drinking in male and female genetically diverse mouse strains. Moreover, recombinant inbred strains that inherited the C57BL/6J allele at the Ap2a1 interval consumed higher amounts of alcohol than those that inherited the DBA/2J allele. Together, these findings highlight the impact of excessive alcohol consumption on the human OFC proteome and identify important cross-species cortical mechanisms and proteins that control drinking in individuals with AUD.

Decreased inter-brain synchronization in the right middle frontal cortex in alcohol use disorder during social interaction: An fNIRS hyperscanning study

BACKGROUND

Alcohol use disorder (AUD) is a widespread mental disorder and has thrust a heavy burden on the health system all over the world. Social cognition and function are reported to be impaired in AUD, but its neural mechanism is rarely investigated. The current study attempts to fill this gap.

METHODS

28 subjects with AUD and 36 healthy controls (HC) were recruited in this study and were paired into 14 AUD dyads and 18 HC dyads. The drinking problems, depression, anxiety, and impulsivity of subjects were measured. Each dyad completed cooperation and competition tasks with simultaneous frontal functional near-infrared spectroscopy (fNIRS) hyperscanning recording. The inter-brain synchronization (IBS) in the frontal cortex was calculated for each dyad and compared between AUD and HC. The significantly altered IBS in AUD was correlated with clinical measures to explore possible influencing factors.

RESULTS

The IBS in the right middle frontal cortex was significantly decreased in AUD under both cooperation (t = -2.257, P = 0.028) and competition (t = -2.488, P = 0.016) task. The IBS during the cooperation task in the right middle frontal cortex in AUD was negatively correlated with non-planning impulsivity (r = -0.673, P = 0.006).

LIMITATIONS

This study used cross-sectional data, which limited the causal inference. The synchronization between other brain regions besides the frontal cortex should be further explored in patients with AUD.

CONCLUSION

The current study could provide new insights into the neural mechanism of social dysfunction in AUD and facilitate clinical intervention in future practice.

Meta-analysis of associations between empathy and alcohol use and problems in clinical and non-clinical samples

AIMS

To (1) measure the aggregated effect size of empathy deficits in individuals with alcohol use disorder (AUD) compared with healthy controls, (2) measure the aggregated effect sizes for associations between lower empathy and heavier alcohol consumption and more alcohol problems in non-clinical samples and (3) identify potential moderators on the variability of effect sizes across studies in these meta-analyses.

METHOD

PsycINFO, PubMed and Google Scholar were searched following a pre-registered International Prospective Register of Systematic Reviews (PROSPERO) protocol (CRD42021225392) and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. We meta-analyzed (using random-effects models) mean differences in empathy between individuals with AUD compared with healthy controls and associations between empathy and alcohol consumption and alcohol problems in non-clinical samples. A total of 714 participants were included in the meta-analysis on clinical samples; 3955 were included in the meta-analyses on non-clinical samples.

RESULTS

Individuals with AUD reported significantly lower empathy than healthy controls [Hedges' g = -0.53, 95% confidence interval (CI) = -0.91, -0.16, k = 9, P < 0.01, Q = 40.09, I2  = 80.04]. Study quality [Q = 1.88, degrees of freedom (d.f.) = 1, P = 0.17] and gender (β = -0.006, Z = -0.60, P = 0.55) were not moderators. Increases in age corresponded to an increase in effect size (β = 0.095, Z = 3.34, P < 0.001). Individuals with AUD (versus healthy controls) had significantly lower cognitive (Hedges' g = -0.44, CI = -0.79, -0.10, P < 0.05), but not affective empathy (Hedges' g = -0.19, CI = -0.51, 0.14, P = 0.27), and the difference between these was significant (Z = 2.34, k = 6, P < 0.01). In non-clinical samples, individuals with lower (versus higher) empathy reported heavier alcohol consumption (r = -0.12, CI = -0.15, -0.09, k = 11, P < 0.001, Q = 9.68, I2  = 0.00) and more alcohol problems (r = -0.08, CI = -0.14, -0.01, k = 7, P = 0.021, Q = 6.55, I2  = 8.34). There was no significant heterogeneity across studies.

CONCLUSION

Individuals with alcohol use disorder appear to show deficits in empathy compared with healthy controls. Deficits are particularly pronounced for older individuals and for cognitive (versus affective) empathy. In non-clinical samples, lower empathy appears to be associated with heavier alcohol consumption and more alcohol problems.

Association Between Brain Structure and Alcohol Use Behaviors in Adults: A Mendelian Randomization and Multiomics Study

IMPORTANCE

Past studies have identified associations between brain macrostructure and alcohol use behaviors. However, identifying directional associations between these phenotypes is difficult due to the limitations of observational studies.

OBJECTIVE

To use mendelian randomization (MR) to identify directional associations between brain structure and alcohol use and elucidate the transcriptomic and cellular underpinnings of identified associations.

DESIGN, SETTING, AND PARTICIPANTS

The main source data comprised summary statistics from population-based and case-control genome-wide association studies (GWAS) of neuroimaging, behavioral, and clinical phenotypes (N = 763 874). Using these data, bidirectional and multivariable MR was performed analyzing associations between brain macrostructure and alcohol use. Downstream transcriptome-wide association studies (TWAS) and cell-type enrichment analyses investigated the biology underlying identified associations. The study approach was data driven and did not test any a priori hypotheses. Data were analyzed August 2021 to May 2022.

MAIN OUTCOMES AND MEASURES

Brain structure phenotypes (global cortical thickness [GCT] and global cortical surface area [GCSA] in 33 709 individuals and left-right subcortical volumes in 19 629 individuals) and alcohol use behaviors (alcoholic drinks per week [DPW] in 537 349 individuals, binge drinking frequency in 143 685 individuals, and alcohol use disorder in 8845 individuals vs 20 657 control individuals [total of 29 502]).

RESULTS

The main bidirectional MR analyses were performed in samples totaling 763 874 individuals, among whom more than 94% were of European ancestry, 52% to 54% were female, and the mean cohort ages were 40 to 63 years. Negative associations were identified between genetically predicted GCT and binge drinking (β, -2.52; 95% CI, -4.13 to -0.91) and DPW (β, -0.88; 95% CI, -1.37 to -0.40) at a false discovery rate (FDR) of 0.05. These associations remained significant in multivariable MR models that accounted for neuropsychiatric phenotypes, substance use, trauma, and neurodegeneration. TWAS of GCT and alcohol use behaviors identified 5 genes at the 17q21.31 locus oppositely associated with GCT and binge drinking or DPW (FDR = 0.05). Cell-type enrichment analyses implicated glutamatergic cortical neurons in alcohol use behaviors.

CONCLUSIONS AND RELEVANCE

The findings in this study show that the associations between GCT and alcohol use may reflect a predispositional influence of GCT and that 17q21.31 genes and glutamatergic cortical neurons may play a role in this association. While replication studies are needed, these findings should enhance the understanding of associations between brain structure and alcohol use.

Association between empathy and drinking among a community sample of heavy drinkers: Sex differences and neural correlates

Alcohol use disorder (AUD) is a major health problem, yet most individuals with AUD do not perceive a need for formal treatment and do not receive treatment. The lack of treatment seeking among individuals with AUD may suggest a lack of self-awareness and insight into the seriousness of AUD related problems, as well as lack of empathy for the impact of one's drinking on others. Recent work has suggested that empathy may be impaired among individuals seeking treatment for AUD. Further these impairments may differ by sex such that males with lower empathy reported more drinking consequences and greater drinking intensity, but there was no association between empathy and drinking among females. The current study used regression analyses (alpha = 0.05) to examine the association between empathy (as measured by the four scales of the Interpersonal Reactivity Index), independent components of gray matter volume in regions associated with empathy, and drinking variables among non-treatment seeking drinkers with AUD (N = 136) and also examined these effects by sex. Results showed greater perspective taking was associated with less temporoparietal and frontotemporal gray matter volume (B(SE) = -0.912 (0.043), p = 0.034). An interaction between perspective taking and sex was associated with craving, such that higher perspective taking was associated with less craving for males only (B(SE) = -0.48 (0.243), p = 0.049; R2 = 0.087). Empathic concern was related to lower percent heavy drinking days for both males and females (B(SE) = -1.57 (0.743), p = 0.035; R2 = 0.11). The current study found empathy may be an important predictor of craving for males and frequency of heavy drinking for males and females. Future work should investigate whether empathy predicts treatment seeking.

Probing the role of the right inferior frontal gyrus during Pain-Related empathy processing: Evidence from fMRI and TMS

Recent studies have suggested that the right inferior frontal gyrus (rIFG) may be involved in pain-related empathy. To verify the role of the rIFG, we performed a functional magnetic resonance imaging (fMRI) experiment to replicate previous research and further designed a noninvasive repetitive transcranial magnetic stimulation (rTMS) experiment to probe the causal role of the rIFG in pain-related empathy processing. We assigned 74 volunteers (37 females) to three groups. Group 1 (n = 26) performed a task in which participants were required to perceive pain in others (task of pain: TP) and we used fMRI to observe the activity of the rIFG during pain-related empathy processing. Then, we applied online rTMS to the rIFG and the vertex site (as reference site) to observe the performance of Group 2 (n = 24; performing TP) and Group 3 (n = 24; performing a control task of identifying body parts; task of body: TB). fMRI experiment demonstrated stronger activation in the rIFG than in the vertex during the perception of pain in others (p < .0001, Bonferroni-corrected). rTMS experiment indicated that when the rIFG was temporarily disrupted, participants perceived pain in others significantly more slowly (p < .0001, Bonferroni-corrected) than when the vertex was disrupted. Our results provide evidence that the rIFG is involved in pain-related empathy processing, which yields insights into how the brain perceives pain in others.

Anxiety during abstinence from alcohol: A systematic review of rodent and human evidence for the anterior insula's role in the abstinence network

Alcohol Use Disorder (AUD) is a chronic, relapsing disease that impacts almost a third of Americans. Despite effective treatments for attaining sobriety, the majority of patients relapse within a year, making relapse a substantial barrier to long-term treatment success. A major factor contributing to relapse is heightened negative affect that results from the combination of abstinence-related increases in stress-reactivity and decreases in reward sensitivity. Substantial research has contributed to the understanding of reward-related changes in AUD. However, less is known about anxiety during abstinence, a critical component of understanding addiction as anxiety during abstinence can trigger relapse. Most of what we know about abstinence-related negative affect comes from rodent studies which have identified key brain regions responsible for abstinence-related behaviors. This abstinence network is composed of brain regions that make up the extended amygdala: the nucleus accumbens (NAcc), the central nucleus of the amygdala (CeA), and the bed nucleus of the stria terminalis (BNST). More recently, emerging evidence from rodent and human studies suggests a fourth brain region, the anterior insula, might be part of the abstinence network. Here, we review current rodent and human literature on the extended amygdala's role in alcohol abstinence and anxiety, present evidence for the anterior insula's role in the abstinence network, and provide future directions for research to further elucidate the neural underpinnings of abstinence in humans. A better understanding of the abstinence network is critical toward understanding and possibly preventing relapse in AUD.

Contribution of sleep disturbances to the heterogeneity of cognitive and brain alterations in alcohol use disorder

Cognitive and brain alterations are common in alcohol use disorder and vary importantly from one patient to another. Sleep disturbances are also very frequent in these patients and remain largely neglected even though they can persist after drinking cessation. Sleep disturbances may be the consequence of specific brain alterations, resulting in cognitive impairments. But sleep disruption may also exacerbate alcohol-related brain abnormalities and cognitive deficits through common pathophysiological mechanisms. Besides, sleep disturbances seem a vulnerability factor for the development of alcohol use disorder. From a clinical perspective, sleep disturbances are known to affect treatment outcome and to increase the risk of relapse. In this article, we conducted a narrative review to provide a better understanding of the relationships between sleep disturbances, brain and cognition in alcohol use disorder. We suggest that the heterogeneity of brain and cognitive alterations observed in patients with alcohol use disorder could at least partially be explained by associated sleep disturbances. We also believe that sleep disruption could indirectly favor relapse by exacerbating neuropsychological impairments required in psychosocial treatment and for the maintenance of abstinence. Implications for clinical practice as well as perspectives for future research are proposed.

Emotional processing and social cognition in alcohol use disorder

OBJECTIVE

To review deficits in emotional processing and social cognition potentially contributing to the dysfunctional emotion regulation and difficulties with interpersonal relationships observed in individuals with alcohol use disorder (AUD) and to provide directions for future research.

METHOD

First is presented a review of emotional and social-cognitive impairments in recently detoxified AUD individuals that include alexithymia, difficulties in decoding others' emotions, and reduced theory of mind and empathy skills. Social cognition disorders in AUD pose different issues discussed, such as whether (1) these deficits are consequences of excessive alcohol consumption or premorbid risk factors for addiction, (2) emotional and social impairments impede positive treatment outcome, (3) recovery of social abilities is possible with sustained abstinence, and (4) AUD patients are unaware of their emotional and social dysfunctions. Finally, current knowledge on structural and functional brain correlates of these deficits in AUD are reviewed.

RESULTS

Emotional and social-cognitive functions affected in AUD can potentially compromise efforts to initiate and maintain abstinence by hampering efficacy of clinical treatment. Such dysfunction can obstruct efforts to enable or reinstate higher-order abilities such as emotional self-regulation, motivation to change, success in interpersonal/social interactions, and emotional insight and awareness of social dysfunctions (i.e., accurate metacognition).

CONCLUSIONS

The present review highlights the need to account for emotional processing and social cognition in the evaluation and rehabilitation of alcohol-related neurocognitive disorders and to consider psychotherapeutic treatment involving remediation of emotional and social skills as implemented in psychiatric and neurological disorders. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Altered brain cortical maturation is found in adolescents with a family history of alcoholism

Substance-naïve offspring from high-density alcohol use disorder (AUD) families exhibit altered subcortical brain volumes structurally and altered executive-functioning and emotion-processing functionally, compared with their peers. However, there is a dearth of literature exploring alterations of cortical thickness (CTh) in this population. T1-weighted structural brain MRI was acquired in 75 substance-naïve male offspring of treatment-seeking early onset (<25 years) AUD patients with high familial loading of AUDs (≥2 affected relatives) (FHP) and 65 age-matched substance-naïve male controls with negative family history from the community. Surface-based CTh reconstruction was done using FreeSurfer. Univariate general linear models were implemented at each vertex using SurfStat, controlling for age (linear and quadratic effects), and head size, to examine the main effect of familial AUD risk on CTh and its relationship with externalizing symptom score (ESS). A Johnson-Neyman procedure revealed that the main effect of familial AUD risk on CTh was seen during adolescence, where the FHP group had thicker cortices involving bilateral precentral gyri, left caudal middle frontal gyrus (MFG), bilateral temporo-parietal junction, left inferior-frontal gyrus and right inferior-temporal gyrus. Thicker cortices in left MFG and inferior-parietal lobule were also associated with greater ESS within both groups. More importantly, these group differences diminished with age by young adulthood. Familial AUD risk is associated with age-related differences in maturation of several higher order association cortices that are critical to ongoing development in executive function, emotion regulation and social cognition during adolescence. Early supportive intervention for a delay in alcohol initiation during this critical phase may be crucial for this at-risk population.

Neuroanatomical and Functional Correlates of Cognitive and Affective Empathy in Young Healthy Adults

Neural substrates of empathy are mainly investigated through task-related functional MRI. However, the functional neural mechanisms at rest underlying the empathic response have been poorly studied. We aimed to investigate neuroanatomical and functional substrates of cognitive and affective empathy. The self-reported empathy questionnaire Cognitive and Affective Empathy Test (TECA), T1 and T2^∗-weighted 3-Tesla MRI were obtained from 22 healthy young females (mean age: 19.6 ± 2.4) and 20 males (mean age: 22.5 ± 4.4). Groups of low and high empathy were established for each scale. FreeSurfer v6.0 was used to estimate cortical thickness and to automatically segment the subcortical structures. FSL v5.0.10 was used to compare resting-state connectivity differences between empathy groups in six defined regions: the orbitofrontal, cingulate, and insular cortices, and the amygdala, hippocampus, and thalamus using a non-parametric permutation approach. The high empathy group in the Perspective Taking subscale (cognitive empathy) had greater thickness in the left orbitofrontal and ventrolateral frontal cortices, bilateral anterior cingulate, superior frontal, and occipital regions. Within the affective empathy scales, subjects with high Empathic Distress had higher thalamic volumes than the low-empathy group. Regarding resting-state connectivity analyses, low-empathy individuals in the Empathic Happiness scale had increased connectivity between the orbitofrontal cortex and the anterior cingulate when compared with the high-empathy group. In conclusion, from a structural point of view, there is a clear dissociation between the brain correlates of affective and cognitive factors of empathy. Neocortical correlates were found for the cognitive empathy dimension, whereas affective empathy is related to lower volumes in subcortical structures. Functionally, affective empathy is linked to connectivity between the orbital and cingulate cortices.