Phases of COGA

Funding for COGA began in 1990, with its first participants enrolled in early 1991.  Conducting a study like COGA requires considerable resources, and we have been extremely fortunate to be funded continuously for the last 30 years by the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of the National Institutes for Health (NIH), through at least 2024. To date, there have been 17,836 individuals in 2246 families who have participated in one or more phases of the study.  Over the years, we have focused on different individuals within these families at different phases of the project.  We provide here a brief overview of the various phases, numbers of subjects recruited, and the focus of each phase.

In Phase I, we assessed 9325 adults aged 18 or older, and 1333 children aged 6-17 in 2246 families. Interviews occurred from 1991-1998. We enrolled and interviewed an index person (called the proband), from alcohol treatment facilities, and then invited additional family members of that person to participate in the study. We studied multiple family members, interviewing individuals aged 7 and older at 6 data collection sites across the country (New York, Connecticut, Indiana, Missouri, Iowa, California). Subjects were evaluated in person (some by telephone) with an interview that was created specifically for the study, called the SSAGA, that covered a wide range of health behaviors and problems that may have occurred throughout the lifetime. A smaller number of families (about 1000) were also invited to complete paper and pencil questionnaires, have their brain waves assessed, and provide a sample of blood for genetic analysis.

In Phase II (roughly from 1995-2005), we studied many of those who were originally interviewed in Phase I, re-interviewing them about 5 years after their original interview. We also invited other members of their families to participate who were not invited originally, or who were unable to do so at that time. In this second Phase, we also added a seventh research site, located at Howard University in Washington DC, to increase the racial/ethnic diversity of our family sample by recruiting additional Black families into the study. In this Phase, measures were updated but remained very similar to the Phase I protocol, including the interview, questionnaires, and brain wave assessments. Also, new tests of cognitive performance were added (neuropsychological tests) to evaluate decision-making, memory, attention, and problem solving. For those who hadn’t yet done so, we sought a blood sample for genetic analysis. Altogether, 8800 adults aged 18 and older, and 2501 children aged 7-17, participated in Phase II.

In Phase III (2003 – 2005), a small set of individuals from Phases I and II was followed up approximately 5 years after their Phase II assessment. This phase included 200 adults as well as 272 adolescents and children. All but 2 of the adults were interviewed in Phase II and Phase III (i.e., had two assessments), and 23 of these adults were also seen in Phase I (i.e., had a total of 3 assessments). Phase III was relatively short-lived, with the goal of continuing assessment while COGA prepared for the Prospective Study.

In 2004, the Prospective Study was launched to evaluate younger members of the original COGA families who were now between the ages of 12 and 22. Some had been studied when they were young children in earlier phases of COGA, but others had not. All had at least one parent who participated in the earlier phases of the project. This study involved interviewing participants every two years, to see how behaviors, including alcohol use and problems, developed and changed over time. Throughout this phase, as children turned 12, they were invited to participate. The measures also included studying brain waves and neuropsychological tests to assess cognitive performance. Many of the participants were one or two generations younger than the original COGA probands (e.g., nephews, grandchildren), but all were drawn from the same family lines. The assessment components were similar to those used in prior phases, but updated to target the youthful group being studied, such as asking about school behaviors and friendship groups. This phase was conducted from 2005 through 2019. Altogether, 3715 individuals have been part of the Prospective Study and have been assessed an average of 4 times.

In 2016-2017, we conducted a one-year Pilot Study of 2,174 subjects from Phases I and II, all of whom were at least 50 years of age and had not been seen for an average of 23 years. One purpose of the pilot was to determine how difficult it would be to find these individuals after such a long period of time. A second goal was to determine how many were deceased (524) and to interview as many individuals as possible within the 1 year time frame allotted for data collection. All totaled, 706 subjects were interviewed by telephone regarding their living situation, their physical health, and their current drinking practices and experiences with alcohol. Because many of these subjects were members of families we were still in contact with for the Prospective Study, we were able to find them a goodly proportion of them.. Almost all (99%) agreed to be contacted again in the future, and that encouraging finding led to the design of a more extensive investigation of older COGA individuals, ushering in the Lifespan Phase.

Currently, we are in the Lifespan Phase (2019 – 2024) of our project. We are evaluating two groups of prior COGA participants. The first group consists of individuals from the Prospective Study who are (or will be by 2023) at least 30 years of age (born between 1982-1993). This sample merits research attention due to the lack of studies that have focused on alcohol use and problems in this midlife age group. The second group is composed of participants from Phases I or II who are currently (or will be by 2023) age 50 or older (born before 1974). These individuals were partly drawn from the Pilot sample. We are recruiting them now to enhance currently limited understanding of alcohol use and problems during this “later life” age period. For both of these groups, the protocol includes a single assessment consisting of an interview, questionnaires, coupled with in-person laboratory based tests of cognition, and brain wave assessments.

The COVID-19 Pandemic required changes to the COGA protocol to ensure the health and safety of research participants and staff. These temporary changes included the suspension of all face-to-face evaluations beginning in March 2020, with interviews conducted by telephone and questionnaires filled out either on mailed paper versions or online via smartphone, computer, tablet at a secure website. At several sites, in-person laboratory testing (EEG/brain wave tests, plus computerized tests of planning, emotion, wellbeing, and memory) resumed during periods when local infection rates were acceptably low. Interviews and questionnaires continued to be administered remotely for the most part. As of this writing (June 2022), resumption of the full in person protocol has not occurred because of continuing concerns about COVID.