Executive control function: A rational basis for the diagnosis of vasculardementia

Problems with diagnostic criteria for vascular dementia (VaD) stem from the inadequacy of the current dementia concept, a paradigm based on amnestic a nd other cortical deficits typical of Alzheimer disease (AD). However, most cases of VaD are due to subcortical lesions such as Binswanger-type perive ntricular white matter ischemia, or strokes causing decreased frontal activ ation and diaschisis-mediated cerebral hypoperfusion. Wie propose a new def inition of dementia based on executive dysfunction and a formal assessment of executive control functions (ECF) for the diagnosis of VaD. The instrume nts proposed are the rapid screening executive clock-drawing task (CLOX; Ro yall et al. J Neurol Neurosurg Psychiatry 1998;64.588-94), and the more com prehensive Executive Interview Test (EXIT25; Royall et al. J Am Geriatr Soc 1992;40:1221-6). Extensive application of these tests in elderly subjects in retirement communities has shown that both are brief, simple to administ er, and more sensitive case-finding tools for cognitively impaired individu als than the Mini-Mental State Examination (MMSE). These three tests (CLOX, EXIT25, MMSE) accurately separate nondemented subjects from those with cor tical or subcortical (frontal system) dementias. In addition, for controlle d clinical trials of VaD, formal evaluation of motor and frontal sphincter functions-usually not considered part of the dementia syndrome-should also be included. Evaluation of gait and falls, timed-walk, manual dexterity, ti med finger-lapping, and frontal bladder control (urge incontinence and noct uria) should improve determination of functional status and disability, and more accurately measure the effects of potential therapies.