Accelerated forgetting in patients with epilepsy: evidence for an impairment in memory consolidation.

Patients with epilepsy frequently complain of memory difficulties yet perform normally on standard neuropsychological tests of memory. It has been suggested that this may be due to an impairment of very long-term memory consolidation processes, beyond those normally assessed in the neuropsychological clinic. We carried out a prospective study of verbal memory over a long-term retention interval of 8 weeks in patients with epilepsy and in controls. Results were compared with performance on conventional tests of memory. Despite normal learning and retention over 30 min, patients with epileptic foci in the left temporal lobe performed disproportionately poorly on the long-term test compared with both patients with epileptic foci in the right temporal lobe and controls. Our findings provide evidence for an extended period of memory consolidation and point to the critical region for this process, at least for verbal material, in the left temporal lobe. The implications of our findings for clinical assessment and therapeutic management of patients with epilepsy are discussed.

Recall and recognition memory in Parkinson's disease.

This study is concerned with recall and recognition memory in patients with Parkinson's disease. The results show that the Parkinson group was significantly impaired on tests of free recall compared to a group of age matched controls. By contrast, when given tests of recognition memory for the same items their performance was practically identical. In recall, significant main effects are reported for serial position and list presentation but no qualitative differences were observed between the two groups on these measures, both of which showed a primacy and recency effect. However, the control subjects recalled significantly more words in their original order of presentation than the patient group, a difference which appears to have occurred at the level of input. It was concluded that although the patient group was able to adopt and use similar strategies to the control subjects, they were less efficient in using these, a difficulty which was attributed to limited capacity due to mental slowness.