The MMSE is not an adequate screening cognitive instrument in studies of late-life depression

BackgroundThe Mini Mental State Examination (MMSE) is frequently used to assess cognition in studies of late-life depression (LLD). However, its sensitivity and specificity in this population are largely unknown. We undertook an analysis of subjects with LLD and hypothesized that: (1) at the traditional cutoff of 24, the MMSE would have low sensitivity in the detection of cognitive impairment; (2) increasing the cutoff score would improve this sensitivity at the expense of a minimal reduction in specificity.MethodsWe analyzed the MMSE scores of 447 non-demented subjects with LLD using the Dementia Rating Scale (DRS) as the gold standard for cognitive function.ResultsUsing the DRS raw total cutoff of 132 as the “gold standard”, the MMSE at a cutoff of 24 has a sensitivity of 8.0% and a specificity of 99.4% in detecting “cognitively impaired” depressed elders. A receiver operating characteristic curve demonstrates that with an MMSE cutoff of 27 instead of 24, its sensitivity more than quadruples and increases to 37.5% while its specificity decreases minimally from 99.4% to 91.3%.ConclusionsIn our sample almost all of those classified as cognitively impaired by the DRS are mislabelled as “cognitively intact” by the MMSE. By using a higher cutoff score, the sensitivity can be increased with a minimal reduction in specificity. Our findings have significant implications for those who study or treat persons with LLD or other neuropsychiatric disorders.