An analysis of the cognitive items of the movement disorders society checklist for the diagnosis of dementia in patients with Parkinson's disease

Objective: Some studies about the Movement Disorders Society checklist for the diagnosis of Parkinson's disease (PD) dementia (PDD) suggested that its accuracy was not totally satisfactory. Our study focused to evaluate the two items of the checklist related to the cognitive assessment.

Methods: We assessed 95 consecutive patients with a diagnosis of PD using the UPDRS, Hoehn and Yahr, Schwab and England scales, Pfeffer Functional Activities Questionnaire, MMSE, Clinical Dementia Rating, clock drawing test, verbal fluency test (animals), digit span, word list battery of CERAD, Frontal Assessment Battery and the 15-item Geriatric Depression Scale The cognitive diagnosis was based on the MDS diagnostic criteria for PDD. The checklist was completed later by a blinded investigator. The data were evaluated using descriptive analysis and calculation of sensitivity, and specificity of the checklist for the diagnosis of PDD.

Results: 33 patients (35%) were diagnosed with PDD. The ROC curve showed that the MMSE cut-off score < 26 had the highest accuracy (sensitivity: 94%, specificity: 55%) for the diagnosis of PDD. Using the checklist with original cut-off scores we found sensitivity of 97% and specificity of 58%. Using an alternative way to interpret the cognitive assessment of the checklist we found sensitivity of 94% and specificity of 89% for the diagnosis of PDD.

Conclusions: Our findings suggest that to improve the accuracy of the checklist, it would be necessary to adjust the way we use and interpret the cut-off scores of the MMSE and of the subtests, without the need to eliminate their use.