Objective: To present preliminary discriminative and normative data for a Spanish version of the MIS in a sample of demented patients (dementia and Alzheimer’s disease (AD)) and controls. To assess its usefulness as a screening instrument for memory problems related to primary dementing disorders, foremost AD.
Design: Cross-sectional validation study within a dementia-clinic setting using a Spanish adaptation of the MIS. Control subjects were drawn from the caregivers accompanying the patients. The MIS was administered as part of a comprehensive neuropsychological and neurological evaluation.
Materials and Methods: The MIS was applied to a group of 187 subjects divided into 128 demented subjects according to DSM-IVR criteria and 59 controls, over 50 years. Within the subgroup of demented subjects 86 received a diagnosis of AD according to NINCDS-ADRDA criteria. Subjects received the MIS, a four word memory test using a specific encoding technique and scoring on an 8 point scale, as part of their neuropsychological workup, but this test was not used for diagnostic purposes.
Sensitivity, specificity and positive predictive value (PPV) were calculated for the MIS against the gold–standard of clinical diagnosis by two blinded clinicians. ROC curves for the discrimination between demented subjects and controls, on the one hand, and AD subjects and controls on the other hand were plotted.
Results: Control subjects were significantly younger and better educated than the demented samples (p<0.001). No sex differences could be established between samples. ROC curves demonstrated excellent discriminative validity for the MIS for dementia on a whole (0.968) and even better for AD (0.995). The MIS presents extraordinary results regarding sensitivity and specificity as well as PPV for different base rates of dementia as well as AD, but it seems that the most effective cut-off score lies at £ 5 points. For all demented subjects this cut-off represents a sensitivity of 0.89 and specificity values of 0.93; these results are even higher for AD (0.99 and 0.93). More importantly, PPV values are above 0.6 for assumed base rates of 10% and more for dementia as well whole and AD. Negative predictive values are almost 1 for all assumed base rates.
Conclusion: The Spanish version of the MIS seems to reliably differentiate between normal and demented subjects. Nevertheless one has to consider the small number of the control sample as well as the setting of the study when interpreting the presented results. Future studies will seek to replicate the present one with a larger sample of normal controls as well as considering pre-forms of dementia for the control sample.
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