Adaptation of dementia screening for vision-impaired older persons: administration of the Mini-Mental State Examination (MMSE).

In epidemiologic field studies on the prevalence and incidence of dementia the problems associated with the cognitive testing of visually impaired individuals are rarely discussed. In the Leipzig Longitudinal Study of the Aged (LEILA 75+) a version of the Mini-Mental State Examination for the visually impaired (MMSE-blind) was employed from which all items requiring image processing had been omitted. To be able to interpret the test results and include vision-impaired individuals in the field study, the scores for the full MMSE were estimated by conducting linear transformation of the scores obtained on the MMSE-blind. The method of linear transformation is based on certain theoretical assumptions that are examined in this article. Linear transformation of scores has proved to be a valid procedure only for individuals with very high or very low cognitive performance. Thus, evaluation of the estimated full MMSE scores based on the norms for the original MMSE is not recommended. A blind version of the MMSE with age- and education-specific norms that has been validated as a screening tool for dementia is therefore presented.