Background Deficits in executive cognitive functionering are common in Huntington’s disease (HD).
Aims To investigate the performance of the clock drawing test (CDT) as a screening tool for cognitive impairment in pre-motor symptomatic and motor symptomatic HD mutation carriers.
Methods In 65 HD mutation carriers participating in this study, the performance of the clock drawing test was assessed, using the Mini-Mental State Examination (MMSE), the Symbol Digit Modalities Test, the Verbal Fluency Test and the Stroop Colour-Word tests as comparisons for the evaluation of cognitive functioning. The CDT was rated according to two different schoring methods: Shulman and Freund scoring system. Interrater reliability was assessed and receiver operator characteristic (ROC) analyses were performed for the CDT against the MMSE and a composite variable for executive cognitive functioning (ExCog) to find optimal cut-off scores. Correlations of the CDT with various cognitive tests, and clinical and neuropsychiatric characteristics were analysed.
Results Interrater reliability was high for both the Shulman and Freund scoring methods (ICC = 0.95 and ICC = 0.90, respectively). Using the MMSE and ExCog as criterion standard, the mean sensitivity of the CDT was 0.82 and the mean specificity 0.79. The CDT showed moderate to high correlations (mean r = 0.71) with the other cognitive tests, particularly so with the Stroop tests. Moderately strong correlations were found between the CDT and disease duration, Total Functional Capacity, and the total motor score of the Unified Huntington’s Disease Rating Scale.
Conclusions The CDT is a suitable screening instrument for cognitive dysfunction in HD, since it was shown to be accurate, particularly so with respect to executive cognitive functioning, and is quick and easy to use.
- Huntington’s disease
- clock drawing