Analysis of Clock Drawings for Developmentally Delayed Individuals

The Clock Drawing Test (CDT) is a neuropsychological measure sensitive to detecting changes in both cognitive and functional abilities in older adults. The purpose of this study was to compare scores on the CDT and levels of cognitive functioning (IQ) and adaptive skills (measured by the Scales of Independent Behavior-Revised; SIB-R) in adults with chronic mental illness and impairments in both areas. The sample was comprised of 83 participants living in a residential facility for individuals with impairments in cognitive and adaptive functioning. Subjects ranged from 20 to 70 years old, (M=43.64 years, SD=12.34). Subjects had all participated in a psychological evaluation within the past two years and impairment in cognitive and adaptive functioning was classified as "mild," "moderate," "severe," or "profound." The CDT was scored using the 0 - 20 point scale devised by Mendez et al (1992). One-way analyses of variance were used to explore the relationship between score on the CDT and SIB-R and IQ classification. Strong relationships were found between CDT and IQ classification [F(3,79)=18.427,P=.001)] with IQ classification explaining 41% of the variance, and with the SIB-R classification [F(2,80)=5.510,P=.006]. This suggests that individuals with more cognitive impairment and those with more impairment in adaptive skills had lower scores on the CDT. The correlation between levels of impairment on cognitive and adaptive skills and performance on the Clock Drawing Test suggests that the CDT may be useful as a screening tool for either kind of impairment and warrants further exploration.