Thiamine-dependent enzyme changes in the brains of alcoholics: relationship to the Wernicke-Korsakoff syndrome.

Chronic alcoholism results in thiamine deficiency as a consequence of poor nutrition, impaired absorption, and decreased phosphorylation to the enzyme cofactor form of the vitamin, thiamine pyrophosphate (TPP). Results of this study demonstrate significant reductions of TPP-dependent enzymes [pyruvate dehydrogenase complex, alpha-ketoglutarate dehydrogenase (alpha KGDH), and transketolase] in autopsied cerebellar vermis samples from alcoholic patients with the clinical and neuropathologically confirmed diagnosis of Wernicke-Korsakoff Syndrome (WKS). Enzyme activities in brain samples from alcoholics without WKS were within normal limits and activities of a nonthiamine-dependent enzyme, glutamate dehydrogenase, were not significantly different from control values in brain samples from alcoholics with or without WKS. These findings provide evidence, for the first time, of a direct implication of TPP-related metabolic processes in the pathogenesis of WKS. Decreased activities of alpha KGDH could be the trigger for a sequence of metabolic events resulting in energy compromise, and ultimately neuronal death in this syndrome.