TOMMORROW neuropsychological battery: German language validation and normative study

INTRODUCTION: Assessment of preclinical Alzheimer's disease (AD) requires reliable and validated methods to detect subtle cognitive changes. The battery of standardized cognitive assessments that is used for diagnostic criteria for mild cognitive impairment due to AD in the TOMMORROW study have only been fully validated in English-speaking countries. We conducted a validation and normative study of the German language version of the TOMMORROW neuropsychological test battery, which tests episodic memory, language, visuospatial ability, executive function, and attention. METHODS: German-speaking cognitively healthy controls (NCs) and subjects with AD were recruited from a memory clinic at a Swiss medical center. Construct validity, test–retest, and alternate form reliability were assessed in NCs. Criterion and discriminant validities of the cognitive measures were tested using logistic regression and discriminant analysis. Cross-cultural equivalency of performance of the German language tests was compared with English language tests. RESULTS: A total of 198 NCs and 25 subjects with AD (aged 65–88 years) were analyzed. All German language tests discriminated NCs from persons with AD. Episodic memory tests had the highest potential to discriminate with almost twice the predictive power of any other domain. Test-retest reliability of the test battery was adequate, and alternate form reliability for episodic memory tests was supported. For most tests, age was a significant predictor of group effect sizes; therefore, normative data were stratified by age. Validity and reliability results were similar to those in the published US cognitive testing literature. DISCUSSION: This study establishes the reliability and validity of the German language TOMMORROW test battery, which performed similarly to the English language tests. Some variations in test performance underscore the importance of regional normative values. The German language battery and normative data will improve the precision of measuring cognition and diagnosing incident mild cognitive impairment due to AD in clinical settings in German-speaking countries.