SOME ASPECTS OF MEMORY DISORDERS CLEARLY DISTINGUISH DEMENTIA OF THE ALZHEIMERS TYPE FROM DEPRESSIVE PSEUDO-DEMENTIA

Two groups of patients affected by mild dementia of the Alzheimer's ty pe (n=42) or by depressive pseudo-dementia (n=26) were given a modifie d version of the Rey's Auditory Verbal Learning Test. The two., groups were roughly matched for overall level of cognitive impairment. The m ain purpose of the research was to determine if some aspects of their memory disorders distinguished the two diagnostic groups. Comparison b etween results obtained on recall and on recognition measures was of l ittle diagnostic usefulness in distinguishing dementia of the Alzheime r's type (DAT) from depressive pseudo-dementia (DPD). A marked prevale nce of the recency over the primacy effect in immediate recall, a high rate of forgetting, and the presence of many intrusion errors on dela yed recall were observed more frequently in DAT than in DPD patients. None of these indices, however, was sensitive and specific enough to a llow a confident diagnostic discrimination at the individual case leve l. The memory measure which best distinguished DAT from DPD patients w as the presence of several false positive errors on delayed recognitio n because DAT patients adopted a very liberal response bias, endorsing many false recognition errors, whereas DPD patients adopted a conserv ative criterion and tended to miss real stimuli, rather than making fa lse recognition errors.