FORGETTING FROM LONG-TERM-MEMORY IN DEMENTIA AND PURE AMNESIA - ROLE OF TASK, DELAY OF ASSESSMENT AND ETIOLOGY OF CEREBRAL-DAMAGE

This study investigated the hypothesis that memory disordered patients suffer of an exalted forgetting rate from long-term memory within the first few minutes following acquisition. For this purpose, we adminis tered to groups of Alzheimer's (AD), Multi-infarct demented (MID), pur e amnesic and age-matched normal controls a test involving immediate a nd 15-min delayed word-list recall and a modified version of the Huppe rt and Piercy's procedure (1978) assessing yes/no Recognition for pict ures at 90 sec, 10 min, 1 hr and 24 hr delay intervals. Results showed an abnormal immediate/delayed performance decline for the word-list r ecall in AD and pure amnesic patients. In the same period, however, th eir Recognition score in the Huppert and Piercy's procedure decayed at normal rate. In the following intervals (1 hr and 24 hr), both groups disclosed abnormal forgetting slopes. Vascular demented patients, by contrast, disclosed fury normal forgetting rates both on the word-list recall and on the Huppert and Piercy's procedure. These findings are discussed in the light of cognitive mechanisms and neuroanatomical str uctures presumably underlying memory consolidation.