Visual and auditory spatial and nonspatial delayed-response performance by Korsakoff and non-Korsakoff alcoholic and aging individuals.

Thirty-six male alcoholics (13 with Korsakoff's syndrome) and 24 controls performed visual and auditory delayed-response tasks sensitive to prefrontal cortical damage in nonhuman primates. Korsakoff patients were consistently impaired compared with other subjects. Impairments by Korsakoff patients were evident when demands were placed on visual processing time (brief stimulus durations), and the deficits became exaggerated with increased demands on short-term memory. Under the most difficult experimental conditions, controls and non-Korsakoff alcoholics who were over 50 years old performed somewhat worse compared with younger groups 27-49 years old. Age-linked deficits were mild compared with Korsakoffs' deficits, and age-group differences disappeared with easier task demands. The results implicate cortical pathology in alcoholism and normal chronological aging and suggest that prefrontal damage accompanies alcoholic Korsakoff's syndrome.

Matching- and delayed matching-to-sample performance as measures of visual processing, selective attention, and memory in aging and alcoholic individuals.

Visual processing time, selective attention to visual cues, and memory for those cues were measured in groups of normal and alcoholic research participants within three different age ranges: young (35-45 yr), middle (46-59 yr) and older (60-70 yr). Performance across groups also was compared to that of alcoholic Korsakoff patients, known to have processing and attentional abnormalities. The matching-to-sample task was employed in which participants are required to match one of two laterally located response choices with a stimulus displayed in the center between them. Duration of the center sample stimulus varied between 20 and 500 msec, and delay between sample offset and response-choice (match) onset varied between 0 and 30 sec. Complexity of the sample stimulus also was varied, containing one or two dimensions (color and/or form). Levels of performance for all groups improved with increased sample stimulus durations, and were negatively related to a stimulus complexity and length of delay. Significant group differences in accuracy were evident with short stimulus exposures; the Korsakoff and older groups made more errors than the younger groups. Similarly, response times were influenced differentially by stimulus duration, stimulus complexity, and the delay between sample and matching stimuli, with young participants (alcoholics and controls) responding fastest. Results emphasize the contribution of processing deficits to other cognitive impairments in aging and alcoholic individuals, as well as the relative independence of aging and alcoholism.

Comparative neuropsychology and Korsakoff's syndrome. III--Delayed response, delayed alternation and DRL performance.

Performance of alcoholic Korsakoff patients was compared with that of patients with Huntington's disease. Broca's aphasia or alcoholism (without clinical signs of memory impairment) on delayed alternation (DA) and delayed response (DR) tests. Korsakoffs were impaired on both tasks, and Huntington patients were impaired on DA only. In a separate experiment, performance by Korsakoffs was compared to that of alcoholic and normal controls on four DRL schedules. Korsakoffs tended to be overresponsive, making errors of commission early within a schedule, and consequently, obtaining fewer reinforcements than the controls.