Premorbid IQ influence on screening tests' scores in healthy patients and patients with cognitive impairment.

Cognitive screening tests are well-established tools for detecting cognitive impairment, but concerns regarding the influence of premorbid intelligence on patient's performance and cognitive status classification remain. Risk of inaccurate assessment especially affects the elders with high or low premorbid intelligence (who are more likely to be misclassified). The present study examines the influence of premorbid intelligence assessed by the TeLPI (an irregular words reading test) on 2 cognitive screening tests, the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA), in healthy participants and patients with cognitive impairments (mild cognitive impairment and Alzheimer disease). Results show that premorbid IQ influences the MMSE and the MoCA scores in both the groups, predicting variance from 8.4% to 33.2%, according to test and group analyzed. Hence, we propose that whenever the MMSE or the MoCA is used, premorbid IQ evaluation should also be considered to ensure correct interpretation and classification.