Researchers differ in their explanations of how and why particular neuropsychological deficits are displayed in alcoholics. One theory proposes that alcoholics may fall into subgroups distinguished by whether their brains are vulnerable to the direct neurotoxic effects of alcohol, to thiamine deficiency, or to both factors (Lishman 1990). According to this viewpoint, alcoholics who are susceptible to alcohol toxicity alone may develop permanent or transient cognitive deficits associated with cortical shrinkage. Those alcoholics who are susceptible to thiamine deficiency alone will develop a mild or short-lived KS state with anterograde amnesia as a salient feature. Alcoholics who suffer from a combination of alcohol neurotoxicity and thiamine deficiency (i.e., have dual vulnerability) will experience widespread damage to large regions of the cerebral cortex as well as to structures deep within the brain. These people will exhibit severe anterograde amnesia as well as other cognitive impairments.
