The clinical aspects of memory disorders: contributions from experimental studies of amnesia and dementia.

Many of the standardized memory tests employed by clinical neuropsychologists fail to demonstrate important differences in the memory disorders of amnesic and demented patients. To exemplify this heterogeneity of amnesic symptoms, the anterograde and retrograde amnesias of patients with Huntington's Disease (HD) and of patients with alcoholic Korsakoff's syndrome are compared. While both patient groups have similar MQs, they differ dramatically in their recall and recognition memory and in their ability to acquire procedural (rule-based) information. The Korsakoff patients are impaired in both recall and recognition memory but are able to acquire and retain mirror reading skills. In contrast, the patients with HD are impaired in their acquisition of procedural knowledge and in verbal recall although their recognition memory approaches normality. The importance of such information for the assessment of the patients' memory disorders is discussed.