The neuropathology of alcohol-specific brain damage, or does alcohol damage the brain?

The aim of this review is to identify neuropathological changes that are directly related to the long-term use of excessive amounts of alcohol (ethanol). There is still debate as to whether alcohol per se causes brain damage. The main problem has been to identify those lesions caused by alcohol itself and those caused by other common alcohol-related factors, principally thiamin deficiency. Careful selection and classification of alcoholic cases into those with and without these complications, together with detailed quantitative neuropathological analyses, has provided us with useful data. There is brain shrinkage in uncomplicated alcoholics which can largely be accounted for by loss of white matter. Some of this damage appears to be reversible. However, alcohol-related neuronal loss has been documented in specific regions of the cerebral cortex (superior frontal association cortex), hypothalamus (supraoptic and paraventricular nuclei), and cerebellum. The data is conflicting for several regions: the hippocampus, amygdala and locus ceruleus. No change is found in the basal ganglia, nucleus basalis, or serotonergic raphe nuclei. Many of the regions that are normal in uncomplicated alcoholics are damaged in those with the Wernicke-Korsakoff syndrome. Dendritic and synaptic changes have been documented in uncomplicated alcoholics and these, together with receptor and transmitter changes, may explain functional changes and cognitive deficits that precede the more severe structural neuronal changes. The pattern of damage appears to be somewhat different and species-specific in animal models of alcohol toxicity. Pathological changes that have been found to correlate with alcohol intake include white matter loss and neuronal loss in the hypothalamus and cerebellum.