Can frontotemporal dementia and Alzheimer's disease be differentiated using a brief battery of tests?

Abstract

To compare the performance of patients with frontotemporal dementia (FTD) and Alzheimer's disease (AD) on a range of simple neuropsychological tests. A battery of neuropsychological tests easily applied at the bedside, consisting of traditional tests of memory, attention and executive function, were given together with tests of motor sequencing and examination of frontal release signs. In addition, we devised a theoretically motivated test of dual attention-a story with distraction which also contained a 'social dilemma'. Specialist memory and cognitive disorders clinic. 12 patients with FTD and 12 patients with AD, matched for overall level of dementia on the Mini-Mental State Examination, were selected. In general, the difference in results between FTD and AD patients was small. However, a composite score derived from the presence of a grasp and pout reflex, the number of perseverations during category fluency for animals and response to the social dilemma within the two stories produced a sensitivity of 83.3% and specificity of 91.6%. There was also a highly significant difference between patients with FTD and AD in scores achieved on the Clinical Dementia Rating Scale reflecting the marked change in behaviour that patients with FTD suffer, even at a stage when memory functions are well preserved. Traditional neuropsychological tests were poor at differentiating cases of FTD and AD; however, a composite (SIFTD) score appears potentially useful but requires prospective validation. Better methods of assessing the changes in comportment that characterize the early stages of FTD are required.