Confabulation, but not executive dysfunction discriminate AD from frontotemporal dementia.

We examined confabulation and performance on frontal/executive tasks in Alzheimer's disease (AD) patients and patients with a diagnosis of probable frontotemporal dementia (FTD). Twenty-two patients with probable AD, 10 patients with probable FTD and 32 normal control subjects entered the study. Executive functions were assessed with the Modified Card Sorting test; a verbal fluency test; the Cognitive Estimation test; and the Stroop test. Confabulations were assessed with a modified version of the Confabulation Battery. The Confabulation Battery included 10 questions tapping each of the following domains: Episodic Memory (memories of personal past episodes), Semantic Memory (knowledge of famous facts and famous people), and Personal Future (personal plans). The results revealed that both AD patients and FTD patients were clearly and equally impaired on tests of executive functions. Both patients' groups confabulated across the three tasks of the Confabulation Battery, but FTD patients confabulated significantly more than AD patients on Episodic Memory and Personal Future. The results failed to provide any evidence of a correlation between the performance on frontal/executive tasks and the tendency to produce confabulatory reports. According to our results, confabulation, more than a deficit of frontal/executive functions, discriminate between AD and FTD. Therefore, screening for confabulation and, possibly, for other types of memory distortions may constitute a useful additional clinical tool in order to discriminate AD from FTD.