Associative and recognition memory for novel objects in dementia: implications for diagnosis

It has been demonstrated that patients with dementia of the Alzheimer's type show particular difficulties with a task that measures memory for object locations [R. Swainson et al. (2001) Dement. Geriatr. Cogn. Disord. 12, 265–80]. The present study followed on from this report by asking whether the deficits seen in dementia of the Alzheimer's type were specific to this condition, or whether they would also be seen in another common neurodegenerative syndrome, frontotemporal dementia. To investigate this important issue, we examined memory for object–location pairs and visual recognition memory for novel patterns using two tests, the Paired Associates Learning and Matching to Sample tasks, from the Cambridge Neuropsychological Testing Automated Battery. The performance of a subset of the patients with dementia of the Alzheimer's type described by Swainson et al., selected on the basis of age and education, was compared with matched groups of frontal variant frontotemporal dementia, semantic dementia and control subjects. In contrast to the patients with dementia of the Alzheimer's type, who showed significant impairment on both memory tests, the two frontotemporal dementia groups did not perform significantly poorer compared with control subjects on nearly all memory measures, other than ‘memory score’ from the paired associates learning task. These findings confirm that tests of episodic memory, especially for the location of objects in space, may be useful in the early diagnosis and differentiation of dementia of the Alzheimer's type.