In summary, across all data collection waves and case and comparison families, in the 30+ years of the COGA project, 17,878 individuals have been assessed at least once with a comprehensive protocol including interviews and questionnaires that capture behaviors, psychosocial characteristics, family background, life course experiences and outcomes from both lifetime and current perspectives. A snapshot of their characteristics derived from the deep phenotyping in COGA is provided in Table 8. In addition, the table displays attributes of several key subsets of the entire COGA sample that have been the focus of intense study by COGA. These include the GWAS sample (n = 12,009), discussed in greater detail elsewhere in this issue (see 4. Genetics); the sample of individuals who have completed at least one electrophysiological protocol administered during COGA's course (n = 9871) and who are the focus of the companion paper in this issue (see 3. Brain function); and lastly those participants with genetic, neurophysiologic and comprehensive phenotypic data. The sample is middle‐aged, with slightly more female participants, notably diverse with 25%–28% from Black race/ethnic groups and 7%–8%
