Use of the cognitive estimations test to discriminate frontotemporal dementia from Alzheimer's disease.

This study investigated the cognitive estimations test (CET) in patients with frontotemporal dementia (FTD) and Alzheimer's disease (AD). The CET consists of questions which reflect judgment and reasoning. FTD patients, who have predominant frontotemporal atrophy, may give more extreme estimates on the CET compared toAD patients, who have greater temporoparietal pathology. The CET was administered to 31 FTD and 31 AD patients of comparable dementia severity plus 31 normal elderly controls. Both dementia groups gave significantly more extreme estimates on the CET than did the controls, and, contrary to expectations, AD patients gave more extreme estimates than did FTD patients. Extreme CET scores correlated with poor savings and calculations scores on neuropsychological tests. In conclusion, the CET may be particularly impaired in AD because it reflects impaired memory and numerical ability as well as disturbed judgment and reasoning. The CET may also be helpful in discriminating some patients in moderate stages of AD from those with FTD.