Learning, retention and generalization of a mirror tracing skill in Alzheimer's disease

The present study examined the ability of 12 patients with probable Alzheimer's disease (AD) and 12 age- and education-matched normal control (NC) subjects to learn and retain the visuomotor skills necessary to efficiently trace a pattern (e.g., a 4- or 6-pointed star) seen only in mirror-reversed view. Those AD (N=6) and NC (N=7) subjects who were able to initially perform the basic mirror tracing task did not differ significantly in initial level of performance, learning over trials, retention of the skill over a 30-min delay interval, and generalization of the skill to a new figure or to the opposite direction of tracing. The AD patients who were unable to initially perform the mirror tracing task were significantly worse than those who could perform the task on several neuropsychological measures sensitive to deficits in problem solving and executive functions, but not on tests of global cognitive decline, memory, language, or visuoperceptual functioning. These results indicate that acquisition and retention of a complex visuomotor skill can proceed normally in the early stages of AD in those individuals who can initially perform the basic task, and that inability to perform the basic task may be related to the frontal lobe dysfunction that is often prominent in the disorder.