Comparison of the serial position effect in very mild Alzheimer's disease,mild Alzheimer's disease, and amnesia associated with electroconvulsive therapy

Individuals given a series of words to memorize normally show better immedi ate recall for items from the beginning and end of the list than for midlis t items. This phenomenon, known as the serial position effect, is thought t o reflect the concurrent contributions of secondary and primary memory, res pectively, to recall performance. The present study compared the serial pos ition effects produced on Trial 1 of the California Verbal Learning Test (C VLT) in mildly demented (N = 25; M MMSE = 20.0) and very mildly demented (N = 25; M MMSE = 25.5) patients with Alzheimer's disease (AD), and age- and education-matched normal control (NC) participants (N = 50). in addition, t he serial position effects of the very mildly demented AD patients were com pared to those of patients with a transient, circumscribed amnesia arising from a prescribed series of electraconvulsive therapy (ECT) treatments for the relief of depressive illness (N = 11). While the NC group exhibited the typical serial position effect, AD patients recalled significantly fewer w ords than NC participants overall, and exhibited a significantly reduced pr imacy effect (i.e.; recall of the first 2 list items) with a normal recency effect (i.e., recall of the last 2 list items). Patients with circumscribe d amnesia due to ECT were as imp aired as the very mildly demented AD patie nts on most standard CVLT measures of learning and memory, but exhibited pr imacy and recency effects, which were within normal limits. These results s uggest that a reduction in the primacy effect, but not the recency effect, is an early and ubiquitous feature of the memory impairment of AD. It is no r, however, a necessary feature of all causes of memory impairment.