Large-scale application of a telephone-based test of cognitive functioning in older adults

Background: The study of cognitive functioning in large epidemiological settings is hampered by a lack of instruments for the remote assessment of cognitive performance, especially when targeting variability across the full range of adult functioning. The present study examined the practicability of such investigations using a recently developed telephone interview (COGTEL). Methods: A subcohort of an on-going epidemiological study in the elderly German population (ESTHER) was interviewed via telephone by trained personell. These data were combined with socio-demographic information obtained by standardized self-administered questionnaires, and analysed by tabulation, histograms, and regression models. Results: A total of 1,697 interviews could be analysed. The eligible participants had a mean (standard deviation) age of 74.0 (2.8) years. The COGTEL total scores closely followed a normal distribution with no evidence of a ceiling effect. In adjusted regression models, COGTEL total and subcomponent scores were negatively associated with age and strongly positively with higher education, whereas the association with sex was less consistent. Conclusions: The results suggest that COGTEL can readily be administered to large study populations and produces valid results. Education should be considered in all investigations using this instrument and requires further in-depth analyses. Future studies will need to elucidate its associations with risk factors and its prognostic potential for cognitive decline and dementia.