![]() 16 One possible way to reconcile these findings is that frontostriatal circuits may be greatly impaired by the time PD progresses to dementia, resulting in executive-functioning deficits.Ĭonceptual deficits are defined as a loss or impairment in accessing knowledge of the attributes, features, and meaning of a clock. 1, 14, 15 However, contrary results have also been reported, with stimulus-bound errors more common in PD with dementia than in AD. Several studies have reported stimulus-bound errors to be more common in AD than in HD, Parkinson’s disease (PD), or frontotemporal dementia. The hands may be absent or pointed toward “10” and/or “11.” This second type of stimulus-bound error can also be rated as a conceptual error. In the second type of stimulus-bound error, the “1” is written near the “11” or between “10 and 11” on the clock. The patient is “attracted” to the strong stimulus source (i.e., “10”) rather than the appropriate response that involves a more complex operation (i.e., setting the minute hand at “2”). ![]() Usually, the instructions are to set the time at “10 after 11.” In one error, the hands are set for “10 ‘til 11” instead of “10 after 11.” The patient fails to re-code the “10” in “10 after 11” as a “2” in order to set the minute hand. 1Ī stimulus-bound response is the tendency of the drawing to be dominated or guided by a single stimulus, most often related to the time-setting instructions. There is evidence that patients with Alzheimer’s disease (AD) make fewer errors on clock-drawing when asked to copy a clock, presumably because there is less utilization of executive functions and semantic memory. Most formal tests first instruct the patient to draw a clock (i.e., draw-to-command) and then copy a clock (i.e., copy-to-command). Some tests provide a predrawn circle and different time-settings. As noted above, there is also variability in how clock-drawing tests are administered. There is greater emphasis on comparing errors due to stimulus-bound responses, conceptual deficit, spatial and/or planning difficulties, or perseveration. It is important to note that many publications do not include all six qualitative errors. 1 He categorized five types of errors in addition to size of the clock ( Figure 1): 1) graphic difficulties 2) stimulus-bound response 3) conceptual deficit 4) spatial and/or planning deficit and 5) perseveration. The most commonly utilized system of qualitative clock-drawing errors was described by Rouleau. The wide variability in how clock-drawing tests are administered and scored is beyond the scope of this review. The focus of this review is to present the major qualitative clock-drawing errors and the evidence linking performance with neuroanatomy. It also has great educational value for patients’ families and in teaching trainees, as it provides an easily understood demonstration of subtle cognitive deficits sometimes challenging to identify in a routine bedside exam. 5 Documenting the type of clock-drawing errors can contribute to the clinical evaluation of patients with suspected neuropsychiatric disorders and syndromes, both in the initial and subsequent assessments. Shulman’s review, concluding that clock-drawing tests are complementary to the Mini-Mental State Exam (MMSE) and provide a significant advance in the early detection of dementia and monitoring cognitive change, also noted that a simple scoring system with emphasis on the qualitative aspects of clock-drawing should maximize its utility. 10– 12 At least 13 scoring systems have been introduced over the years. For example, recent studies have reported the use of a clock-drawing test for diagnosing and grading the severity of hepatic encephalopathy, predicting rehabilitation outcomes after traumatic brain injury (TBI), and assessing functional status in veterans with deployment-related mild TBI. 7– 9 Although the majority of studies utilize the clock-drawing test to assess cognition in the context of screening for dementia, other conditions have also been evaluated. 5, 6 Although in use since the 1960s, it was made popular in 1983, when Goodglass and Kaplan incorporated it into the Boston Aphasia Battery. ![]() 4 Reviews of the research literature support its use as a reliable screening tool for cognitive dysfunction, particularly for dementia. Clock-drawing is a simple and effective test to include in the neuropsychiatric assessment of patients.
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