Neural and cognitive biomarkers of binge and heavy drinking

BACKGROUND: Theories suggest two motivations that drive people to consume alcohol at pathological levels: (1) seeking of short-term pleasurable effects and (2) alleviation of unpleasant states. The former is associated with binge drinking (BD; i.e. high intake during fewer occasions) and the latter with heavy drinking (HD; substantial intake during more occasions). Although direct comparisons have not been made, BD has been associated with impairments in top-down executive control (related to frontal-parietal regions) and HD has been linked to bottom-up changes in internal mentation (related to the default mode network anatomical structure and function). This dissertation compares the two drinking patterns with the goal of testing for differential neurocognitive and neuroanatomical characteristics that would be indicative of two disorder subtypes. METHODS: The sample consisted of adult participants with a history of adolescent onset: BD (N = 16), HD (N = 15), and Healthy Controls (HC; N = 21). All groups were equated on age, education, amount of lifetime alcohol consumed (BD and HD groups), as well as other factors. The study compared group performance on an affective go/no go task and group differences in brain volume and cortical thickness based on structural MRI. RESULTS: Behavioral results showed a higher number of errors for the HD group, in comparison to other groups. Volumetric results indicated a smaller bilateral ventral diencephalon in both BD and HD, in comparison to the HC, and smaller bilateral globus pallidus in BD only. Cortical thickness analyses revealed a thinner left superior parietal region (overlapping with the dorsal attention and fronto-parietal networks) in BD, whereas a left medial occipito-parietal region was thicker in HD (overlapping mainly with the visual network). CONCLUSION: These data, interpreted in the context of prior studies, suggest that BD findings might be indicative of an executive control dysregulation that could contribute to continued BD. HD findings might be indicative of tissue damage due to frequent drinking. Prior research has found the occipital region to have the highest concentration γ-Aminobutyric acid receptors that are affected by alcohol, which might explain the thicker occipital region findings in the HD group

Effects of OEF/OIF-Related Physical and Emotional Co-Morbidities on Associative Learning: Concurrent Delay and Trace Eyeblink Classical Conditioning

This study examined the performance of veterans and active duty personnel who served in Operation Enduring Freedom and/or Operation Iraqi Freedom (OEF/OIF) on a basic associative learning task. Eighty-eight individuals participated in this study. All received a comprehensive clinical evaluation to determine the presence and severity of posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI). The eyeblink conditioning task was composed of randomly intermixed delay and trace conditioned stimulus (CS) and unconditioned stimulus (US) pairs (acquisition) followed by a series of CS only trials (extinction). Results revealed that those with a clinical diagnosis of PTSD or a diagnosis of PTSD with comorbid mTBI acquired delay and trace conditioned responses (CRs) to levels and at rates similar to a deployed control group, thus suggesting intact basic associative learning. Differential extinction impairment was observed in the two clinical groups. Acquisition of CRs for both delay and trace conditioning, as well as extinction of trace CRs, was associated with alcoholic behavior across all participants. These findings help characterize the learning and memory function of individuals with PTSD and mTBI from OEF/OIF and raise the alarming possibility that the use of alcohol in this group may lead to more significant cognitive dysfunction

A structural MRI study of differential neuromorphometric characteristics of binge and heavy drinking

Background: Alcohol misuse often manifests in two different patterns of drinking; Binge Drinking (BD; ≥4 (women) or ≥ 5 (men) drinks/day, ≤12 days/month) or Heavy Drinking (HD; ≥3 (women) or ≥4 (men) drinks/day, ≥16 days/month). Although direct comparisons have not been made, structural MRI studies indicate that the two types of drinking behaviors might be associated with different neuromorphometric characteristics. Methods: This study used a cross-sectional design to compare brain structure (using MRI derived subcortical volume and cortical thickness measures) between participants with histories of BD (N = 16), HD (N = 15), and Healthy Controls (HC; N = 21). Whole-brain analyses were used to quantify group differences in subcortical volume and cortical thickness. Resulting cortical thickness clusters were quantified for their areas of overlap with resting-state network parcellations. Results: BD was associated with decreased volumes of the bilateral global pallidus and decreased cortical thickness within the left superior-parietal cluster (p < .05). This cortical cluster overlapped in surface area with the dorsal-attention (50.86%) and the fronto-parietal network parcellations (49.14%). HD was associated with increased cortical thickness in the left medial occipito-parietal cluster (p < .05). This cluster primarily overlapped with the visual network parcellation (89%) and, to a lesser extent, with a widespread number of network parcellations (dorsal-attention: 3.8%; fronto-parietal: 3.5%; default-mode: 3.2%). Conclusions: These data indicate that histories of BD and HD patterns are associated with distinct neuromorphometric characteristics. BD was associated with changes within the executive control networks and the globus pallidus. HD was associated with widespread changes, that are primarily localized within the visual network. Keywords: Alcohol, Cortical thickness, Brain volume, Binge drinking, Heavy drinkin