Retrograde memory in cerebrovascular disease and Alzheimer's disease.

Retrograde memory is frequently tested in the mental status examination of patients with stroke or degenerative dementia. The goal of this experiment was to compare gradients of retrograde memory in patients without neurologic disease (n = 26), patients with cerebrovascular disease (n = 43), and patients with probable Alzheimer's disease (n = 27). Patients were asked to recall and then name photographs of the 6 most recent US presidents. The free recall of patients with both cerebrovascular disease and probable Alzheimer's disease formed an exaggeration of the normal forgetting curve seen in control patients, in that the most recent presidents were most likely to be remembered. For photo naming, control patients showed essentially no forgetting, whereas patients with cerebrovascular disease or Alzheimer's disease had substantial memory loss with no temporal gradient. Alzheimer's disease caused significantly worse retrograde memory loss than did cerebrovascular disease, despite the two groups' equivalence in global intellectual functioning. Consistent with the focal or multifocal nature of cerebrovascular disease, stepwise multiple regression of retrograde memory on neuropsychological testing indicated that producing names by free recall was predicted by aphasic deficits, and that photo naming was predicted by visuoperceptual deficits. In Alzheimer's disease, free recall was predicted primarily by deficits in verbal new learning, consistent with amnesia, whereas photo naming was predicted by loss of general knowledge, consistent with dementia. The results are consistent with the idea that free recall of names from the past is a form of episodic memory, whereas naming of famous faces from the past is a form of semantic memory.