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Introduction and aims: There is emerging evidence that heavy long‐term alcohol consumption may alter the neuroimmune profile. We conducted a meta‐analysis of the association between alcohol use disorder (AUD) and the extent of neuroinflammation using cerebrospinal (CSF), PET (Positron Emission Tomography), and postmortem studies. Design and methods: A comprehensive search of electronic databases was conducted using the Preferred Reporting Items for Systematic Review and Meta‐Analysis Protocols (PRISMA‐P) for AUD‐related terms in combination with neuroinflammatory markers and cytokine‐ and chemokine‐related terms for CSF, PET, and postmortem studies. Participants had to meet established criteria for AUD and/or heavy alcohol consumption with dependence features and be compared with healthy controls. Papers retrieved were assessed for inclusion criteria and a critical appraisal was completed using the Newcastle‐Ottawa Scale. A meta‐analysis was conducted on postmortem and PET studies. Results: Eleven papers met the inclusion criteria with CSF, PET, and postmortem studies included in the final analysis. Postmortem studies demonstrate significant heterogeneity (푄 (14) = 62.02, 푝 < 0.001), with the alcohol group showing higher levels of neuroimmune markers than controls (푑 = 1.50 [95% CI 0.56, 2.45]). PET studies demonstrated a lower [11C] PBR28 total volume of distribution (VT) for translocator protein in the hippocampus (g = −1.95 [95% CI −2.72, −1.18], p < 0.001) of the alcohol group compared to controls. Conclusion: There is emerging evidence across multiple diagnostic modalities that alcohol impacts neuroimmune signaling in the human brain. [ABSTRACT FROM AUTHOR]

Background: Postmortem brain tissue provides an important resource to investigate various brain disorders, including those resulting from the effects of alcohol abuse. Unlike the traditionally recognized confounders to tissue quality (e.g., coma, hypoxia), our understanding of the effects of liver disease is incomplete. The aim of this study was to determine the effects of liver pathology, and in particular cirrhosis resulting in hepatic encephalopathy (HE), on 2 postmortem brain tissue quality markers, brain pH and RNA integrity. Methods: We measured tissue quality markers in a cohort of alcohol abuse and control cases collected by the NSW Tissue Resource Centre. Cerebellar tissue was used to evaluate both brain pH and RNA quality (as indicated by the RNA integrity number: RIN). A histological assessment was performed on each case to exclude coexisting pathologies (e.g., cerebrovascular disease, hypoxic encephalopathy, neurodegenerative disease) and to assess the presence or absence of HE. Autopsy reports were reviewed for liver pathology and toxicology. Results: Analysis revealed that cases of alcohol abuse had a lower mean (±SD) brain pH, 6.46 (±0.3) as compared with the control mean 6.64 (±0.2). The mean RIN for the alcohol abuse group was 6.97 (±1.3) and controls 7.66 (±0.5). The severity of liver pathology affected both brain pH ( p < 0.0001) and RIN ( p < 0.0001). The comparison between cirrhotic cases highlighted increased degradation of RNA in cases with cirrhosis resulting in HE ( p = 0.0095). A similar effect was seen on brain pH ( p = 0.0019). Conclusions: The results show that the presence of cirrhosis and, more so, HE reduces the pH and RIN of postmortem brain tissue. [ABSTRACT FROM AUTHOR]