Sensitivity of Clock Drawing Test Alone to Screen for Cognitive Impairment in Patients with Parkinson's Disease

Cognitive impairment is a prevalent non-motor symptom of Parkinson's disease (PD), significantly impacting patient quality of life. The Clock Drawing Test (CDT) evaluates cognitive abilities, including planning, organization, and executive functions such as attention, memory, and visuospatial skills. This study aimed to determine the sensitivity of the CDT in diagnosing cognitive impairment in PD.

We reviewed the records of 44 PD patients (16 female, 28 male) diagnosed with dementia (30 patients) or mild cognitive impairment (14 patients) between 2018 and 2022. These patients were compared to 106 visitors to the neurological outpatient clinic, serving as a control group. A separate researcher assessed the patients' CDT scores, maintaining confidentiality of all other patient data except age and education level.

Among the 44 PD patients, two with mild cognitive impairment were rated as normal, while all PD dementia cases were identified solely through the CDT. In the healthy control group, 72 out of 106 individuals reported no cognitive complaints, whereas 34 individuals (32.1%) reported cognitive complaints as assessed by a blind investigator. The CDT demonstrated a positive predictive value of 55.3% and a negative predictive value of 97.3%. Sensitivity was calculated at 95.5%, and specificity was 67.9%.

The findings suggest that the CDT is sensitive in detecting cognitive impairment in PD patients with cognitive deficits. While the CDT serves as an effective rapid screening tool, high scores indicate the absence of cognitive impairment, but low scores alone are insufficient for a definitive diagnosis of dementia. Comprehensive neurological evaluation and detailed cognitive assessment remain essential for confirming dementia diagnoses.