Non-verbal learning is impaired in very mild Alzheimer's disease (CDR 0.5): Normative data from the learning version of the Rey-Osterrieth Complex Figure Test

Mild cognitive impairment (MCI) is a transitional state between normal aging and dementia. Although there have been some studies on the role of verbal memory in learning ability, there have been no reports on the part played by visual memory. In the present study, the Rey-Osterrieth Complex Figure Test (RCFT) was given to healthy subjects and to those with MCI to determine if visual memory was maintained in these two groups. Additionally, normative data from the learning version of the RCFT for Japanese subjects were examined, for purpose of reference. The participants consisted of 381 clinical dementia rating (CDR) 0 subjects and 137 CDR 0.5 subjects who could perform the full set of RCFT tasks. The CDR 0 group had significantly higher scores than the CDR 0.5 group in all trials. The CDR 0 participants also showed a significant step-by-step learning effect, while the CDR 0.5 participants did not show a significant learning effect. These results suggest that the CDR 0 participants maintained intact learning abilities of encoding and retrieval, while the CDR 0.5 participants did not do so; but further studies will be needed to clarify these findings.