Alzheimer's disease and alcoholism: possible interactions.

The purpose of this investigation was to test the hypothesis that chronic exposure to alcohol may accelerate Alzheimer's disease (AD), either by independently adding receptor losses or by accelerating the AD disease process itself. Muscarinic [3H]quinuclidinyl benzilate and benzodiazepine [3H]-flunitrazepam receptor binding in homogenates of human autopsy brains were determined in four nonalcoholic and seven alcoholic AD brains and in histologically normal brains from 20 alcoholics and 20 nonalcoholics. Muscarinic binding was decreased in alcoholic AD compared with nonalcoholic AD in the parahippocampal region of frontal cortex, premotor temporal cortex, and amygdala, but not in the hippocampus. Benzodiazepine receptors were lost from the temporal cortex and amygdala, but the difference in the amygdala was not statistically significant. Plaque counts considered a marker of the severity of AD were not increased in the brains of alcoholics compared with nonalcoholics. Larger receptor losses in some alcoholic AD were associated with low plaque counts. Since all of these patients were severely demented, it is tentatively suggested that the receptor losses resulting from alcoholism may have contributed to the dementia in these AD patients.