Chronic cigarette smoking is very common in alcohol use disorders (AUD). Nevertheless, the effects of chronic smoking on in-vivo measures of brain injury in alcohol-dependent individuals have not been studied. Thus, it is unknown if the full extent of brain atrophy, cell membrane and microstructural injury, derangement of neurometabolism, low cerebral blood flow, and neurocognitive dysfunction described in alcohol dependence are solely attributable to chronic alcohol use, or if chronic smoking influences these measures. Preliminary results from our ongoing magnetic resonance (MR) and cognitive studies indicate that chronic smoking appears to exacerbate alcohol-induced abnormalities in brain morphology, neurochemistry, and blood flow, and may adversely affect recovery of surrogate markers of neuronal and cell membrane/myelin integrity as well as aspects of neurocognition during short-term abstinence from alcohol. The main goal of this competing continuation is therefore to test in treated alcohol dependent individuals (i) if chronic smoking compounds alcohol-induced neurobiological brain injury, (ii) if chronic smoking effects are functionally significant, and (iii) if chronic smoking influences recovery of alcohol-induced neurobiological and neurocognitive dysfunction during abstinence from alcohol. We will continue to apply an integrative approach of combining information from different MR modalities and neurocognitive testing in the same individual longitudinally to assess the neurobiological and functional consequences of chronic smoking in treated alcohol-dependent individuals. Specifically, we will continue our longitudinal 1.5 Tesla MR studies to quantitate regional brain structure, brain metabolites (reflecting neuronal and myelin viability), and regional cerebral blood flow as well as repeat comprehensive neurocognitive testing. In addition, new MR studies at high magnetic field (4T) will improve the quality of cerebral blood flow and diffusion data, and will measure cortical levels of glutamate and Y-aminobutyric acid, amino acids critically involved in the initiation and maintenance of substance dependence. Relationships of MR-derived and neurocognitive measures will determine the functional relevance of neurobiological measures and their changes over time and test the effects of chronic smoking on functional neurocircuitry in alcoholism. This application is responsive to PA-05-074 in that the proposed research will improve our understanding of the mechanisms underlying alcohol- and smoking induced brain injury and its potential reversibility with abstinence from alcohol. Chronic smoking may have hitherto unrecognized but significant contributions to these neurobiological processes and their cognitive and clinical consequences. The knowledge to be gained from this translational research can be used directly for public education, in new approaches to pharmacologic and behavioral interventions for AUD, and in monitoring treatment outcome.
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