Comparison of the Clock Test and a questionnaire-based test for screening for cognitive impairment in Nigerians

Abstract

Background: Since it is projected that by 2020 seventy percent of the elderly will reside in developing countries, a reliable screening method for dementia and cognitive impairment in general in populations with diverse languages, culture, education and literacy will be needed. We sought to determine if the Clock Test, a screening test for dementia, was suitable for use in a Nigerian population. Study design: Cross-sectional survey of 54 men and 12 women from Northern Nigeria. Researchers administered two dementia screening tools: a questionnaire-based test adapted for use in a Nigerian population and the Clock Test. Results: Overall, 53.0% of the subjects had an abnormal Clock Test whereas 10.6% of the subjects had an abnormal questionnaire score. Only 9.1% of the subjects had abnormal scores on both tests. Subjects with more schooling had a greater probability of having a positive clock concept (understanding that a circle represented a clock). Of these with more than 6 years of schooling, 91.0% had a positive clock concept. Subjects with a negative clock concept were more likely to have an abnormal Clock Test (93.3%) than a questionnaire (26.6%). Conclusions: The main finding of our study was the discrepancy between the results of the Clock Test and the questionnaire. Performance on the Clock Test appeared to have been heavily influenced by education level, indicating the test is not universally applicable across cultures. The questionnaire-based test appears to reduce the effects of illiteracy on assessing dementia in a Nigerian population. Larger studies should be done to control for how education affects the assessment of dementia.