Objectives: To examine the validity and reliability of a brief cognitive screen instrument, the Neuropsychiatry Unit Cognitive Assessment Tool (NUCOG), in patients with dementia, major psychiatric disorders and neurological disorders, and to compare its performance with the Mini-Mental State Examination (MMSE).
Method: The NUCOG was undertaken with the MMSE on a total of 347 individuals, with 82 subjects in the control group and 265 in the patient group. The patient group consisted of patients with dementia (n=65), non-dementing neurological disorders (n=44) and psychiatric illness (n=156). The patient group was further broken into subgroups of dementing and psychiatric disorders for further analysis. A subgroup of patients (n=22) underwent detailed neuropsychological testing.
Results: The NUCOG and MMSE scores, which correlated strongly, were highest in the control group, and lowest in the dementia group, with psychiatric and neurological patients scoring similarly. Internal consistency and reliability were high. Scores were significantly affected by age and years of education. The NUCOG differentiated the four broad groups and the dementia subgroups more strongly than the MMSE. The NUCOG subscale scores correlated strongly with most neuropsychological subtests undertaken. At a cut-off score of 80/100, sensitivity of the NUCOG for detection of dementia was 0.84 and specificity 0.86.
Conclusions: The NUCOG is a valid and reliable cognitive tool that is sensitive and specific for the detection of dementia. The NUCOG was able to differentiate dementia and psychiatric subgroups which were not able to be discriminated on MMSE scores. The NUCOG appears to be a well-tolerated, reliable and highly useful clinical tool that offers benefits over and above the MMSE.