Neurocircuitry of emotion and cognition in alcoholism: contributions from white matter fiber tractography
ABSTRACT Chronic alcoholism is characterized by impaired control over emotionally motivated actions towards alcohol use. Neuropathologically, it is associated with widespread brain structural compromise marked by gray matter shrinkage, ventricular enlargement, and white matter degradation. The extent to which cortical damage itself or cortical disconnection by white matter fiber pathway disruption contribute to deficits in emotion, cognition, and behavior can be investigated with in vivo structural neuroimaging and diffusion tensor imaging (DTI)-based quantitative fiber tracking. Tractography in alcoholism has revealed abnormalities in selective white matter fiber bundles involving limbic fiber tracts (fornix and cingulum) that connect cortico-limbic-striatal nodes of emotion and reward circuits. Studies documenting brain-behavior relationships support the role of alcoholism-related white matter fiber degradation as a substrate of clinical impairment. An understanding of the role of cortico-limbic fiber degradation in emotional dysregulation in alcoholism is now emerging.
SourceAvailable from: Jochem M Jansen[Show abstract] [Hide abstract]
ABSTRACT: Cognitive flexibility has been associated with prefrontal white matter (WM) integrity in healthy controls (HCs), showing that lower WM integrity is associated with worse performance. Although both cognitive flexibility and WM integrity have been found to be aberrant in alcohol-dependent (AD) patients, the relationship between the two has never been tested. In this study, we investigated the association between WM tract density and cognitive flexibility in patients with AD (n = 26) and HCs (n = 22). In order to assess the influence of AD severity, we also included a group of problematic drinkers (PrDs; n = 23) who did not meet the AD criteria. Behavioral responses and brain activity during a cognitive flexibility task were measured during functional magnetic resonance imaging. Probabilistic fiber tracking was performed between the dorsolateral prefrontal cortex and the basal ganglia; two crucial regions for task switching. Finally, the task-related functional connectivity between these areas was assessed. There were no signifi-cant group differences in the task performance. However, compared with HCs, AD patients and PrDs showed decreased WM integrity and increased prefrontal brain activation during task switching. Evidence is presented for a compensatory mechanism, involving recruitment of additional prefrontal resources in order to compensate for WM and neural function impairments in AD patients and PrDs. Although present in both alcohol groups, the PrDs were more successful in invoking this compensatory mechanism when compared to the AD patients. We propose that this may therefore serve as a protective factor, precluding transition from problematic drinking into alcohol dependence.Addiction Biology 12/2014; DOI:10.1111/adb.12199 · 5.91 Impact Factor
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ABSTRACT: Background Previous studies have demonstrated the presence of a social cognition factor as an element of general cognition in healthy control and clinical populations. Recently developed measures of social cognition include the social perception and faces subtests of the Wechsler Advanced Clinical Solutions (ACS) Social Cognition module. While these measures have been validated on various clinical samples, they have not been studied in alcoholics. Alcoholism has been associated with emotional abnormalities and diminished social cognitive functioning as well as neuropathology of brain areas underlying social processing abilities. We used the ACS Social Perception and Faces subtests to assess alcoholism-related impairments in social cognition.Methods Social cognitive functioning was assessed in 77 abstinent alcoholic individuals (37 women) and 59 nonalcoholic control participants (29 women), using measures of the ACS Social Cognition module and subtests of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) that contain a social cognition component (Picture Completion and Comprehension). Group and gender differences in ACS and WAIS-IV performance were assessed, as well as relationships between measures of alcoholism severity and social cognitive functioning.ResultsAlcoholics performed significantly worse than nonalcoholics on the ACS measures of Affect Naming and Faces Content. Alcoholic men were impaired relative to alcoholic women on Prosody Face Matching and Faces Content scores. Among alcoholics, longer durations of heavy drinking were associated with poorer performance on Affect Naming, and a greater number of daily drinks were associated with lower Prosody Face Matching performance. For alcoholic women, a longer duration of abstinence was associated with better performance on Affect Naming.Conclusions Alcoholic men and women showed different patterns of associations between alcoholism indices and clinically validated social cognition assessments. These findings extend into the social cognition domain, previous literature demonstrating the presence of cognitive deficits in alcoholism, their association with alcoholism severity, and variability by gender. Moreover, because impairments in social cognition can persist despite extended abstinence, they have important implications for relapse prevention.Alcoholism Clinical and Experimental Research 12/2014; 38(12). DOI:10.1111/acer.12566 · 3.31 Impact Factor
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ABSTRACT: Abstract Background: Diffusion tensor imaging has been used to explore white matter changes in heroin-dependent patients; however, results have been inconsistent. Objectives: The current study meta-analytically examines the neuroimaging findings of all studies published before 2014 using the novel technique of Effect Size Signed Differential Mapping (ES-SDM). Methods: Two independent investigators searched three databases for whole-brain voxel-based fractional anisotropy morphometric studies involving heroin use without comorbid polysubstance abuse. Of 59 initial primary studies, four met stringent inclusion criteria. Results: Results from this preliminary analysis indicate that heroin abusers may have significant reductions in fractional anisotropy in the bilateral frontal sub-gyral regions extending from the limbic structures to the prefrontal association cortices, implicating damage to the cingulum and superior longitudinal fasciculus. Exploratory moderator analyses indicate that the potential damage in the left cingulate gyrus may increase with longer use and decrease after long-term abstinence. Conclusion: These preliminary findings suggest that heroin abuse is significantly associated with damage to white matter integrity. These results are considered preliminary and analyses should be revisited with more primary studies focusing on either long- or short-term abuse as well as abstinence.The American Journal of Drug and Alcohol Abuse 02/2015; 41(2):1-6. DOI:10.3109/00952990.2014.985829 · 1.47 Impact Factor