Characterizing mood disorders in the AFFECT study: a large, longitudinal, and phenotypically rich genetic cohort in the US
Authors: Dalby Maria , Vitezic Morana , Plath Niels , Hammer-Helmich Lene , Jiang Yunxuan , Tian Chao , Dhamija Devika , Wilson Catherine H. , Hinds David ,   23andMe Research Team, Aslibekyan Stella , Auton Adam , Babalola Elizabeth , Bell Robert K. , Bielenberg Jessica , Bryc Katarzyna , Bullis Emily , Coker Daniella , Partida Gabriel Cuellar , Das Sayantan , Elson Sarah L. , Filshtein Teresa , Fletez-Brant Kipper , Fontanillas Pierre , Freyman Will , Faaborg Anna , Fuller Shirin T. , Gandhi Pooja M. , Granka Julie M. , Heilbron Karl , Hernandez Alejandro , Hicks Barry , Jewett Ethan M. , Kukar Katelyn , Lin Keng-Han , Lowe Maya , McCreight Jey C. , McIntyre Matthew H. , Micheletti Steven J. , Moreno Meghan E. , Mountain Joanna L. , Nandakumar Priyanka , Noblin Elizabeth S. , O’Connell Jared , Huang Yunru , Kim Joanne S. , Lane Vanessa , Petrakovitz Aaron A. , Poznik G. David , Schumacher Morgan , Shastri Anjali J. , Shelton Janie F. , Shi Jingchunzi , Shringarpure Suyash , Tchakouté Christophe Toukam , Tran Vinh , Tung Joyce Y. , Wang Xin , Wang Wei , Wilton Peter , Wong Corinna , Sullivan Patrick F. , Buckholtz Joshua W. , Smoller Jordan W. 
Published: March 2022

There has recently been marked progress in identifying genetic risk factors for major depression (MD) and bipolar disorder (BD); however, few systematic efforts have been made to elucidate heterogeneity that exists within and across these diagnostic taxa. The Affective disorders, Environment, and Cognitive Trait (AFFECT) study presents an opportunity to identify and associate the structure of cognition and symptom-level domains across the mood disorder spectrum in a prospective study from a diverse US population.

Participants were recruited from the 23andMe, Inc research participant database and through social media; self-reported diagnosis of MD or BD by a medical professional and medication status data were used to enrich for mood-disorder cases. Remote assessments were used to acquire an extensive range of phenotypes, including mood state, transdiagnostic symptom severity, task-based measures of cognition, environmental exposures, personality traits. In this paper we describe the study design, and the demographic and clinical characteristics of the cohort. In addition we report genetic ancestry, SNP heritability, and genetic correlations with other large cohorts of mood disorders.

A total of 48,467 participants were enrolled: 14,768 with MD, 9864 with BD, and 23,835 controls. Upon enrollment, 47% of participants with MD and 27% with BD indicated being in an active mood episode. Cases reported early ages of onset (mean = 13.2 and 14.3 years for MD and BD, respectively), and high levels of recurrence (78.6% and 84.9% with >5 episodes), psychotherapy, and psychotropic medication use. SNP heritability on the liability scale for the ascertained MD participants (0.19–0.21) was consistent with the high level of disease severity in this cohort, while BD heritability estimates (0.16–0.22) were comparable to reports in other large scale genomic studies of mood disorders. Genetic correlations between the AFFECT cohort and other large-scale cohorts were high for MD but not for BD. By incorporating transdiagnostic symptom assessments, repeated measures, and genomic data, the AFFECT study represents a unique resource for dissecting the structure of mood disorders across multiple levels of analysis. In addition, the fully remote nature of the study provides valuable insights for future virtual and decentralized clinical trials within mood disorders.