To assess the clock drawing testing (CDT) and diffusion tensor magnetic resonance imaging (DT-MRI) differences between probable Alzheimer’s dementia (AD) and vascular dementia (VaD) and the CDT correlation with the DT-MRI.

Elderly patients presenting at the Geriatric outpatient clinic-Ain Shams University Hospitals, Egypt over a period of 6 months were recruited for the study. Tools of assessment including activities of daily living, geriatric depression scale-15 items, Mini-mental status examination, and Clock drawing test using Shulman et al. scoring system were applied to all participants. Diagnosis of dementia and its subtypes was confirmed using DSM-IV criteria. From the assessed subjects, thirty participants; ten cases of probable AD, ten cases of VaD and ten controls, were randomly chosen for assessment using DT-MRI, where apparent diffusion coefficient (ADC), and fractional anisotropy (FA), were evaluated in 15 regions of interest in the cerebral hemispheres.

VaD cases showed significantly worse performance in CDT than AD cases with more prevalence of spacing errors among them. CDT had significant correlation with age, MMSE and ADL. Dementia was associated with increased ADC and decreased FA in DT-MRI. VaD had lower FA than AD. CDT was significantly correlated with white matter integrity of several areas on DT-MRI.

CDT differs among VaD and AD with a range of radiological correlations. DT-MRI is a sensitive and discriminative technique for evaluation of patients with dementia including probable AD and VaD. Larger studies are needed for establishing reference ranges.