Intrusion errors in the figural memory of patients with Alzheimer's and Huntington's disease.

The tendency of patients with dementia of the Alzheimer type (DAT) and Huntington's disease (HD) to produce prior-item intrusion errors on a figural memory task was assessed. Patients' and elderly control subjects' immediate recall of figures from the Visual Reproduction Test (VRT) of the Wechsler Memory Scale (WMS) was scored for the presence of prior-figure intrusion errors (i.e., characteristics unique to one figure included in the reproduction of a subsequent figure). Results indicate that both patient groups produced more prior-figure intrusion errors than did the NC group, and that DAT patients made significantly more intrusion errors in their reproductions than did HD patients matched for overall severity of dementia. These data suggest that prior-item intrusion errors are evident on figural as well as on verbal memory tasks and that DAT patients are more likely to produce such errors than are equally demented patients with a "subcortical" dementia.