The Collaborative Study on the Genetics of Alcoholism: Overview

Abstract

Alcohol use disorders (AUD) are commonly occurring, heritable and polygenic disorders with etiological origins in the brain and the environment. To outline the causes and consequences of alcohol-related milestones, including AUD, and their related psychiatric comorbidities, the Collaborative Study on the Genetics of Alcoholism (COGA) was launched in 1989 with a gene-brain-behavior framework. COGA is a family based, diverse (~25% self-identified African American, ~52% female) sample, including data on 17,878 individuals, ages 7-97 years, in 2246 families of which a proportion are densely affected for AUD. All participants responded to questionnaires (e.g., personality) and the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) which gathers information on psychiatric diagnoses, conditions and related behaviors (e.g., parental monitoring). In addition, 9871 individuals have brain function data from electroencephalogram (EEG) recordings while 12,009 individuals have been genotyped on genome-wide association study (GWAS) arrays. A series of functional genomics studies examine the specific cellular and molecular mechanisms underlying AUD. This overview provides the framework for the development of COGA as a scientific resource in the past three decades, with individual reviews providing in-depth descriptions of data on and discoveries from behavioral and clinical, brain function, genetic and functional genomics data. The value of COGA also resides in its data sharing policies, its efforts to communicate scientific findings to the broader community via a project website and its potential to nurture early career investigators and to generate independent research that has broadened the impact of gene-brain-behavior research into AUD.

Keywords: AUD; EEG; ERP; SSAGA; alcohol dependence; alcohol use disorder; brain; developmental; family; genomics; lifespan; longitudinal; psychiatric.

FIGURE 1

Distribution of family sizes (mean 8.1, range 1–87) in COGA families (2246 families; N = 17,878; age range 7–97).

FIGURE 2

Distribution of density of individuals with alcohol use disorders (AUD) as a percentage of family members in families ascertained for AUD, stratified by broad categories of family size. The original COGA probands were ascertained from treatment facilities, based upon DSM‐IIIR and Feighner alcohol dependence criteria; with consent, additional family members were interviewed. Diagnostic definitions have changed over the decades; thus the data plotted reflect whether an interviewed family member met criteria for DSM‐IIIR or DSM‐IV alcohol abuse or dependence or DSM‐5 AUD (without requirement of clustering of criteria within a 12 months period). The X‐axis provides broad percentage groups of interviewed family members with AUD (e.g., 10%–20% with AUD) while the individual bars on the Y‐axis represent the percentage of families with a given density of interviewed members with AUD. For instance, 29.3% of families with 2–4 individuals interviewed per family (i.e., family size of 2–4) have 41%–50% of their interviewed family members diagnosed with AUD, while nearly 32% of these families (n = 454) have 91%–100% diagnosed with AUD. Note that families with 1 individual are not shown.