There is considerable variability in the neuroradiological signs of neuropathology of alcoholism; some individuals have massive brain shrinkage and others little demonstrable effect. A relationship between total lifetime alcohol dose and brain tissue volume shrinkage or CSF space expansion is typically elusive and does not account for a substantial portion of the dysmorphology. Autopsy incidence of Wernicke's encephalopathy (WE) associated lesions, undetected in life, suggests an under appreciation of the high prevalence of nutritional deficiency (especially thiamine) among alcoholics. Further, the neuroradiological findings of uncomplicated (i.e., nonamnesic) alcoholics appear as a graded version of those seen when WE progresses to the amnesic Korsakoff syndrome (KS or WKS). The human literature is sprinkled with references to the """"""""neurotoxicity of alcohol"""""""" but with little direct support for this assertion and with the following questions begged: is alcohol neurotoxic if nutrition is adequate, or do repeated bouts of subclinical nutritional deficiency underlie human alcoholic neuropathology? Animal models demonstrate acute neuronal necrosis after binge alcohol, but at very high doses in alcohol naive animals, sometimes with significant mortality. Alcohol effects are primarily described in the hippocampal-entorhinal-olfactory circuit, known for its neuroplasticity, neurogenesis and unique susceptibility to environmental insult. Thiamine deficiency studies in rodents consistently produce substantial brain pathology, including white matter and cortical lesions, typical of human alcoholics in vivo and at autopsy, but also have a signature lesion pattern involving the mammillothalamic tract, including the mammillary bodies, fornix, anterior thalamic nuclei, in addition to the superior and inferior colliculi and anterior superior vermis. We propose to develop a translational animal model, using high resolution structural magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) to examine thiamine deficiency, modeled as controlled dietary plus pyrithiamine-induced thiamine deficiency (PITD), acute binge ethanol treatment and their interaction in rats. We will also study WKS-at-risk alcoholics with repeated sustained binge drinking and historical reporting of poor nutrition during the binges. The overarching hypothesis is that nutritional deficiency makes as great or greater contribution than alcohol per se to the observed neuropathology, and the combination is synergistically damaging. We propose four specific aims:
Specific Aim 1 : Measure the development, extent, location and recovery of neuroradiologically-detectable brain damage with repeated bouts of PITD in rats.
Specific Aim 2 : Measure the effects on the hippocampus and fimbria of repeated 5-day, acute alcohol binge in rats.
Specific Aim 3 : Model human drinking in rats with combined alcohol binges plus thiamine deficiency.
Specific Aim 4 : Translation from rats to humans: Identify neuroradiological signs of nutritional deficiency compounding alcoholism-related dysmorphology in human alcoholics. ? ? ?
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