We will evaluate the performance of healthy older participants (N = 300, age range 60 to 89 years) for three days at enrollment and then at 6-month intervals for three years thereafter. The goal is to characterize changes in performance to aging and task experience in a group of older subjects.

We will compare the performance of normal participants (N = 100, age range 18 to 89) on computerized and manually administered cognitive tasks.

We will gather normative data from participants across the age range (N = 100, ages 18 to 89) for three days at enrollment, to better characterize test-retest reliability scores on Day 1 tasks.

We will evaluate the performance of healthy older participants (N = 1200, age range 50 to 89 years) for three days at enrollment and then at 6-month intervals for three years thereafter. In the aim of better understanding health disparities in cognitive testing, this group will be divided into four cohorts: 300 African American participants; 300 Asian American participants; 300 Latino English-speaking participants; and 300 Latino Spanish-speaking participants, who will complete a Spanish translation of our computerized cognitive tests.

The California Cognitive Assessment Battery (CCAB) is a collection of computerized cognitive tests that will be telemedically administered to participants in their homes using a tablet computer and accessories provided by the research team. Testing may also occur in research laboratories. Previous versions of CCAB tests have been described in 16 manuscripts which describe (a) the psychometric characteristics of normative data collected in large participant populations (300 to 2,300 subjects for different tests) and (b) the sensitivity of CCAB tests for detecting performance abnormalities in patients with traumatic brain injury (TBI) and in control participants simulating the cognitive deficits that follow mild TBI.

Multiple behavioral outcome measures will be obtained from each cognitive test including measures of response time (in milliseconds) and accuracy (in percent correct). Recordings of subject's verbal responses will also be analyzed phonologically and automatically transcribed to permit the lexical, syntactic, and semantic analysis of speech output. Questionnaire data will be used to identify factors that may influence performance on the cognitive tests. The primary outcome measures are the scores obtained during enrollment testing that predict a decline in longitudinal performance.