Word list versus story memory in Alzheimer disease and frontotemporal dementia

Memory impairment, characterized by a pattern of rapid forgetting, is the hallmark deficit in Alzheimer's disease (AD). Memory deficits have also been reported in frontotemporal dementia (FTD), and are thought to reflect diminished organizational and attentional abilities leading to a pattern of decreased acquisition of new information. The present study compared patients with AD, the behavioral variant of FTD, and cognitively intact elderly control subjects on two types of memory tests: story memory and word list recall. The percent of information recalled immediately (encoded), after a delay, and the percent retention between these conditions was calculated for both tests. The results showed that FTD patients encoded and recalled more information from the story than AD patients. No difference was found between FTD and AD patients for encoding of the word list. However, FTD patients recalled more words after a delay than AD patients. Percent retention on both tasks was also greater for the FTD group. The results suggest that patterns of performance on different tests of memory, and, in particular, measures of retention, can be useful in differentiating memory impairment in AD from that of FTD on cognitive testing.