Equating conversion norms for the Mini-Mental State Examination and Montreal Cognitive Assessment in healthy subjects and patients with neurodegenerative disorders

Introduction: The Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) are globally recognized as validated cognitive screening tests widely used. Objective/aim: The present study attempted to provide conversion tables from the MMSE to the MoCA and vice versa, deriving them from a large population of healthy older adults and a representative clinical sample of subjects with different types of cognitive decline within the spectrum of Alzheimer's (AD) and Parkinson's (PD) diseases. Methods: A total of 1423 Italian participants, including healthy adults (n = 1203), individuals with AD (n = 93), and with PD (n = 127) were assessed using the MMSE and MoCA. Conversion tables were developed using log-linear smoothing equipercentile equating (LSEE). The reliability of the conversion was assessed through the Root Mean Square Error (RMSE) in a train-test approach confirmed in the whole sample. Results: The findings demonstrated that the LSEE method enables the development of conversion tables allowing users to identify the corresponding MoCA score for each MMSE score within the studied groups, and vice versa. The estimation error RMSE was 1.8, 2.9, and 3.2 for the conversion of MoCA from MMSE and 1.2, 2.3, and 2.2 for the conversion of MMSE from MoCA in healthy subjects, AD, and PD, respectively. The reliability of the conversion is higher in healthy subjects and for higher values of MoCA and MMSE. Conclusion: Results report easy-to-use conversion norms for transforming raw MMSE score to MoCA and vice versa, highlighting areas were the conversion has a strong or low reliability depending on the score range.