Tactile perceptual skill learning and motor skill learning in Alzheimer's disease

We studied capacity of acquiring tactile Hiragana character reading and bi-manual motor coordinated tracing in patients with Alzheimer's disease (AD). Subjects were 47 patients with probable AD based on NINCDS-ADRDA criteria. We also studied 25 normal volunteers matched for age, gender and educational level as controls. Sixteen patients failed to complete the tactile character reading task for various reasons. This group of patients differed significantly from the other 31 patients in severity of the illness, the former including patients with more severe AD. In the task, the speed of reading improved in 14 out of the 31 patients over time. Character recognition memory was below normal in all patients. Among the cognitive tests, only FIQ of WAIS-R correlated with the rate of improvement. In the motor task 28 of the 31 patients who completed the tactile task participated. Twenty of 28 patients improved over time. The task did not correlate with any cognitive tests, or with the results of the tactile task. These results indicate relative independence of the tactile learning process from the motor learning process. Also, the tactile as well as the motor learning process correlated poorly with processes involved in declarative memory.