Assessing the sensitivity and specificity of cognitive screening measures for people with Parkinson's disease

While cognitive impairment is a recognised feature of Parkinson's disease (PD), few studies have evaluated the validity of brief cognitive screening measures compared to a comprehensive neuropsychological assessment. This studies aim was to evaluate the sensitivity and specificity of the Mini-Mental State Examination (MMSE), Modified Mini-Mental State Examination and Dementia Rating Scale (DRS-2) to detect cognitive impairment in individuals with PD.

Fifty-eight participants were administered the MMSE, 3MS, DRS-2 and a neuropsychological battery. ROC analyses were conducted to assess their effectiveness in classifying cognitive impairment.

None of the three measures demonstrated good sensitivity or specificity to detect single domain cognitive impairment. For detecting impairment on two or more cognitive domains, the MMSE and DRS-2 yielded excellent sensitivity (88%) and specificity (78% and 76% respectively), at cut-off scores of 28 and 136 respectively. The 3MS demonstrated excellent sensitivity (88%) and good specificity (60%) at cut off score of 94.

The MMSE and DRS-2 have excellent discriminant ability to classify multi-domain cognitive impairment in PD, however, their ability to detect more focal cognitive impairment is limited. Given that focal domain may be an indicator that could be useful in early detection of cognitive impairment for people with PD, this finding has implication for the use of these measures as screening tools in clinical practice.