Tranel, D., Rudrauf, D., Vianna, E. P., & Damasio, H. (2008). Does the Clock Drawing Test have focal neuroanatomical correlates? Neuropsychology, 22(5), 553-562.
The authors investigated the neuroanatomical correlates of the clock drawing test (CDT), using 133 patients whose lesions provided effective coverage of most of both hemispheres and underlying white matter. The study was designed to contribute new information about the neuroanatomical correlates of CDT performance.
The neuroanatomical analysis was based on magnetic resonance (MR) data obtained in a 1.5 Tesla General Electric Sigma scanner with a 3D SPGR sequence yielding 1.5 mm contiguous T1 weighted coronal cuts, or, in a few subjects in whom an MR could not be obtained, on computerized axial tomography (CT) data. Some of the patients with left hemisphere lesions were recovered aphasics, but none of them had residual aphasia so severe as to interfere with their basic comprehension of the neuropsychological tasks. The participants were neurological patients with focal brain damage (overall N 133; 77 men, 56 women), selected from the Patient Registry in the Division of Behavioral Neurology and Cognitive Neuroscience at the University of Iowa. Subjects were selected if they had (1) a CDT performance from the chronic epoch (defined as 3 months or more post lesion onset), and (2) a single, focal lesion in one hemisphere.
The authors break down patterns of responses on the CDT into two categories:
- Impaired spatial organization and number placement pattern - gaps in between numbers, errors in hand length/placement. Much more frequent in people with right hemisphere lesions.
- Impaired time setting error pattern - spatial drawing and numbers are relatively accurate, but the time setting is inaccurate. Much more frequent in subjects with left hemisphere lesions.
The study concludes that CDT has reliable neuroanatomical correlates, especially in the right parietal region and left inferior frontoparietal opercular region.
- Clock drawing tests (CDT) may provide some insight into the focal area of damage when neuro-imaging is not readily available.
CDT errors in time setting tended to be related to deficits in language processing.
- CDT errors in spatial organization tended to be related to visuoconstructional and visuospatial processing defects.
- The authors note that there does not currently exist any evidence to imply that different time settings might influence success on this test. They note that a variety of time settings are instructed (with the most common being “ten past eleven”), though the time doesn’t seem to matter- only that a specific time is instructed, rather than just “draw a clock.”