Incidental learning and verbal memory in individuals with Parkinson disease

Researchers report that nondemented patients with Parkinson disease (PD) are impaired on recall tests, but perform normally on recognition tests. Patients with PD and dementia are impaired on both tests. PD patients with and without dementia also are reported to benefit less from semantic cues presented at recall. These studies used explicit learning in which people are aware they will be tested on the material. In the present study, individuals were presented words in an incidental learning task; they were unaware that their memory would be tested. Eighty-three PD patients with no dementia, 18 PD patients with questionable dementia, 14 PD patients with mild dementia, and 48 elderly controls incidentally learned words in a semantic categorization task. They were later given recognition, free recall, and cued recall tests. In free recall, only the dementia group performed significantly poorer than the control group. In recognition, the dementia group had a higher false alarm rate than the other groups. All participants, including those with dementia, benefitted from category names provided in a cued recall test.