Temporal ordering and short-term memory deficits in Parkinson's disease.

Previous studies of remote memory function have indicated a dissociability between memory for the content and date of past events and suggested selective deficits of dating capacity in Parkinson's disease (PD). The present study examined the hypothesis that poor dating in PD is linked to a specific deficit in temporal contextual memory which also affects new learning. Patients with PD and patients with Alzheimer's disease (AD) were compared in their ability to perform tasks of content recognition and recency discrimination of words presented sequentially. Compared with AD patients, PD patients were disproportionately impaired in recency discrimination relative to content recognition. When performance was analysed as a function of retention interval, AD patients showed impairment in both tasks at all intervals. PD patients, by contrast, showed deficits in content recognition at the short stimulus-test intervals only, possibly reflecting the clinical phenomenon of bradyphrenia. These results suggest that recency discrimination deficits and impaired short-term memory processing are specific cognitive deficits in PD that may be linked to subcortical deafferentation of the frontal lobes.