Digital Clock Drawing: Differentiating “Thinking”versus“Doing” in Younger and Older Adults with Depression

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Abstract
Psychomotor slowing has been documented in depression. The digital Clock Drawing Test (dCDT) provides: (i) a novel technique to assess both cognitive and motor aspects of psychomotor speed within the same task and (ii) the potential to uncover subtleties of behavior not previously detected with non-digitized modes of data collection. Using digitized pen technology in 106 participants grouped by Age (younger/older) and Affect (euthymic/unmedicated depressed), we recorded cognitive and motor output by capturinghowthe clock is drawn rather than focusing on the final product. We divided time to completion (TTC) for Command and Copy conditions of the dCDT into metrics of percent of drawing (%Ink)versusnon-drawing(%Think) time. We also obtained compositeZ-scores of cognition, including attention/information processing (AIP), to explore associations of%Inkand%Thinktimes to cognitive and motor performance. Despite equivalent TTC,%Inkand%ThinkCommand times (Copy n.s.) were significant (AgeXAffect interaction:p=.03)—younger depressed spent a smaller proportion of time drawing relative to thinking compared to the older depressed group. Command%Thinktime negatively correlated with AIP in the older depressed group (r=−.46;p=.02). Copy%Thinktime negatively correlated with AIP in the younger depressed (r=−.47;p=.03) and older euthymic groups (r=−.51;p=.01). The dCDT differentiated aspects of psychomotor slowing in depression regardless of age, while dCDT/cognitive associates for younger adults with depression mimicked patterns of older euthymics. (JINS, 2014,20, 1–9)

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