Bedside assessment of frontal degeneration: distinguishing Alzheimer's disease from non-Alzheimer's cortical dementia.

Two instruments, the Executive Interview (EXIT) and the Qualitative Evaluation of Dementia (QED), that are useful in the evaluation of frontal system failure are discussed. The ability of these instruments to discriminate frontal-type dementia (FTD) from Alzheimer's disease (AD) and the dementia of major depression (DMD) was examined in 100 consecutive elderly dementia patients presenting to a multidisciplinary geriatric clinic. All groups showed executive impairment by the EXIT, and 46% of the FTD patients were found to be unimpaired by the Mini-Mental State Examination (MMSE). The AD and FTD groups differed significantly from the DMD group on the QED. The QED alone could not distinguish AD from FTD cases. However, mapping of EXIT scores against MMSE (errors) scores revealed that AD and FTD follow very different regression lines.