Assessing cognitive impairment in older people: the Watson clock drawing test.

A non-random sample of 331 community-based clients aged 75 years and over, who were being cared for at home, were involved in a longitudinal study to assess cognitive impairment (CI). The clock drawing test (CDT) using the Watson et al (1993) scoring protocol was used to determine its utility as a tool for community nurses to assess CI. In the first phase of the study, 294 CDTs were used in analysis and 58.8% (n = 172) of participants were cognitively impaired. Subsequent assessments at 9 months and 18 months using both the CDT and the Mini-Mental State Examination (MMSE) confirmed the high initial level of cognitive impairment among the sample. Over the course of the study 37 participants who had high CDT scores were admitted to institutional care and their cognitive status continued to decline. Among those who remained in the community, the percentage with some degree of cognitive impairment remained high, and over the course of the study there was a significant linear decline in the mean MMSE score. The CDT takes less time to administer than the MMSE and appears to be a more sensitive tool for detecting early changes in cognition. The CDT could therefore be useful as an initial assessment tool by community mental health nurses to help facilitate early intervention for older clients who are beginning to experience cognitive changes.