Frequencies and Neuropsychological Characteristics of Errors in the Clock Drawing Test

Few studies have investigated associations between types of clock drawing test (CDT) errors and cognitive impairment.

To explore associations of qualitative errors in the CDT with comprehensive neurocognitive assessment scores and clinical diagnosis.

Outpatients at a memory clinic were enrolled. Frequencies of errors determined by Cahn's method were explored according to cognitive status (cognitively normal [CN] (n = 279), mild cognitive impairment [MCI] (n = 321), and Alzheimer's disease [AD]) (n = 575). Neuropsychological assessment scores were compared between participants with and without errors.

Stimulus-bound response (SB) was relatively rare (6.8%) in the CN group but was markedly more common in the MCI (23.4%) and AD (33.2%) groups. Conceptual deficit (CD) was found in more than 20%of CN individuals, as well as about 50%of AD patients. Planning deficit (PD) frequencies were relatively similar among the groups. SB in both of CN and MCI individuals, and CD in both of CN and MCI individuals were associated with lower scores in several neuropsychological assessments. Meanwhile, PD was not associated with lower assessment scores in any of CN, MCI, or AD individuals.

The frequencies of SB and CD increased from CN, MCI, to AD but showed somewhat different patterns. Both SB and CD were associated with lower cognition in all three cognitive stages.