Temporal gradient in the remote memory impairment of amnesic patients with lesions in the basal forebrain.

Recall and recognition of premorbid public events were studied in four groups of subjects. Dementia patients showed equal losses from all time periods compared to normal controls. In contrast, two groups of amnesic patients showed extensive remote memory losses, which were most marked for the last few years prior to onset. The difference between recall and recognition was similar in the groups. The results indicate that the retrograde amnesia associated with aneurysms of the anterior communicating artery cannot be distinguished from that of amnesia with other etiologies. Implications of the finding of a temporal gradient in the retrograde amnesia of non-alcoholic amnesics are discussed.