Introduction: Many instruments had been designed to screen dementia that their utilities are faced with some limitations. In addition, there is modicum of studies comparing the clinical dementia rating scale and clock drawing test on normal people without diagnosed dementia. The goal of the present study was comparing clinical dementia rating scale and clock drawing test among Iranian people, older than 65.
Method: In this analytical cross-sectional study, 80 over-65 year-old subjects were enrolled by convenient sampling. Demographic and clinical features including; age, sex, education level, medication, and diseases were collected. Then clinical dementia rating scale and clock drawing test were performed for each subject. To test the relationship between variables, independent t-test, Chi2 and exact Fisher test were used and were analyzed with SPSS ver.20.
Results: The age showed a positive correlation with clinical dementia rating score (P=0.00, r=0.36) and a negative correlation with clock drawing test score (P=0.00, r=0.46). But there was no relationship between gender and prevalence of dementia based on neither the clock drawing test nor the clinical dementia rating system. The mean clock drawing test score showed a significant difference between healthy people and those with blood pressure (P=0.02), psychosis (P=0.01) and manic-depression (P=0.03) disorders. Also, the mean clinical dementia rating score revealed a significant difference a between healthy subjects and those suffering from blood pressure (P=0.00), IHD (P=0.00), and COPD (P=0.04) diseases. In subjects suffering from at least one disease, the rate of dementia diagnosis by clock drawing test and clinical dementia rating systems did not significantly differed. However, in people without any disease, the prevalence of dementia diagnosed with clock drawing test was significantly higher than that diagnosed with clinical dementia rating (P=0.00).
Conclusion: based on findings of the present study, the education level as well as suffering from a disease can affect the clock drawing test results. Therefore, it seems that the clock drawing test system in people over 65 years, compared with the conventional clinical dementia rating system, might not be an appropriate diagnostic approach for dementia. However, more studies are needed to be done in future.