Telephone assessment of cognitive function in the late-onset Alzheimer's disease family study.

BACKGROUND Administration of cognitive test batteries by telephone has been shown to be a valid and cost-effective means of assessing cognition, but it remains relatively uncommon in epidemiological research. OBJECTIVES To develop composite cognitive measures and assess how much of the variability in their scores is associated with mode of test administration (ie, in person or by telephone). DESIGN Cross-sectional cohort study. SETTING Late-Onset Alzheimer's Disease Family Study conducted at 18 centers across the United States. PARTICIPANTS A total of 1584 persons, 368 with dementia, from 646 families. MAIN OUTCOME MEASURES Scores on composite measures of memory and cognitive function derived from a battery of 7 performance tests administered in person (69%) or by telephone (31%) by examiners who underwent a structured performance-based training program with annual recertification. RESULTS Based in part on the results of a factor analysis of the 7 tests, we developed summary measures of working memory, declarative memory, episodic memory, semantic memory, and global cognition. In linear regression analyses, mode of test administration accounted for less than 2% of the variance in the measures. In mixed-effects models, variability in cognitive scores due to center was small relative to variability due to differences between individuals and families. CONCLUSIONS In epidemiologic research on aging and Alzheimer disease, assessment of cognition by telephone has little effect on performance and provides operational flexibility and a means of reducing both costs and missing data.