Abstract
Genetic moderation of interpersonal psychotherapy (IPT) efficacy for economically disadvantaged women with major depressive disorder was examined. Specifically, we investigated whether genotypic variation in corticotropin releasing hormone receptor 1 (CRHR1) and the serotonin transporter gene (5-HTT) moderated effects of IPT on depressive symptoms over time. We also tested genotype moderation of IPT mechanisms social adjustment and perceived stress. Nontreatment seeking urban women at or below the poverty level with infants were recruited from the community (N = 126; M age = 25.33; SD = 4.99; 54.0% African-American, 22.2% Caucasian, and 23.8% Hispanic/biracial) and randomized to individual IPT or enhanced community standard (ECS). Results revealed that changes in depressive symptoms over time depended on both intervention group and genotypes (5-HTTLPR and CRHR1). Moreover, multiple-group path analysis indicated that IPT improved depressive symptoms, increased social adjustment and decreased perceived stress at post-treatment among women with the 0 copies of the CRHR1 TAT haplotype only. Finally, improved social adjustment at post-intervention significantly mediated the effect of IPT on reduced depressive symptoms at 8 months post-intervention for women 0 copies of the TAT haplotype only. Post-hoc analyses of 5-HTTLPR were indicative of differential susceptibility, albeit among African-American women only.
Over 26% of Americans ages 18 and older suffer from a diagnosable mental disorder in a given year (Kessler, Chiu, Demler, & Walters, 2005), including enduring conditions such as depression, bipolar disorder, and schizophrenia. Major depressive disorder (MDD) is a significant public health problem that is particularly prevalent in women during their childbearing years (Kessler et al., 1993; Kessler et al., 2003; Regier et al., 1988). Twenty percent of women will experience an episode of MDD at some point during their lives and women residing in poverty are at even greater risk for MDD (Segre, O’Hara, Arndt, & Stuart, 2007; Williams & Colling, 1995). Despite the magnitude of the problem, many economically disadvantaged women do not seek treatment or receive sub-standard treatments that are ineffective (Wang et al., 2005). Of particular concern are findings that racial and ethnic minority groups, many of whom reside in poverty, receive poorer quality healthcare and have worse outcomes when care is received (Smedley, Stith, & Nelson, 2002). Herein we evaluate whether individuals vary in response to the provision of an evidence-based psychosocial treatment for MDD as a function of genetic moderation. In secondary analyses, we explore differential susceptibility in relation to self-reported ethnoracial group status.
