Cognitive procedural learning in early Alzheimer's disease: Impaired processes and compensatory mechanisms

Introduction. The aim of this study was to study cognitive procedural learning in early Alzheimer's disease (AD). Methods. Cognitive procedural learning was assessed using the Tower of Hanoi (TH) task. In order to take account of possible interactions between different systems during cognitive procedural learning, we also measured non-verbal intellectual functions, working memory, and declarative memory. Results. Our results showed an apparent preservation of cognitive procedural learning in AD and a deleterious effect of the disease on verbal intelligence and declarative memory. Correlational analyses revealed a difference between AD patients and control participants in the type of processing they applied to the task. Conclusion. The non-involvement of declarative memory would appear to be partly responsible for a slowdown in the cognitive procedural dynamics of AD patients. As the AD patients were unable to use their declarative memory, they were still in a problemsolving mode at the end of the learning protocol and had to implement higher order cognitive processes (i. e., compensatory mechanisms) to perform the procedural task.