Letter to the Editor: Bias in the measurement of bias. Letter regarding 'Citation bias and selective focus on positive findings in the literature on the serotonin transporter gene (5-HTTLPR), life stress and depression'

Associations of the MAOA uVNTR genotype and 5-HTTLPR/rs25531 haplotype with psychopathic traits

Previous studies have linked polymorphisms of the monoamine oxidase A (MAOA uVNTR) and serotonin transporter gene (5-HTTLPR) to individual differences in the expression of psychopathic traits, but findings remain inconsistent. One possible reason is that these studies have treated psychopathy as a unitary construct when there is accumulating evidence that there are variants or subtypes. We used a variable-centered and a person-centered approach by (a) examining putative genetic correlates of psychopathy across individuals and (b) comparing the frequencies of the MAOA uVNTR genotype and 5-HTTLPR/rs25531 haplotype between empirically derived subtypes of psychopathy, respectively. Notably, we included the often neglected rs25531 polymorphism, which is closely connected to the 5-HTTLPR. Based on data from male offenders and community volunteers, structural equation modeling indicated that the 5-HTTLPR/rs25531 haplotype was specifically associated with interpersonal deficits beyond the overarching psychopathy construct. Latent profile analysis revealed four clusters that were labeled non-psychopaths, sociopaths, callous-conning, and psychopaths. The low-activity variant of the 5-HTTLPR/rs25531 haplotype was significantly more frequent in the callous-conning compared to the non-psychopathic subtype. There were no effects for the MAOA uVNTR. The results illustrate that psychopathy should not be treated as a unitary construct but that there are variants with specific profiles of psychopathic traits, and that the 5-HTTLPR/rs25531 haplotype plays a role in the manifestation of interpersonal deficits from a variable-centered as well as from a person-centered view.

Stress sensitization to depression following childhood adversity: Moderation by HPA axis and serotonergic multilocus profile scores

Childhood adversity appears to sensitize youth to stress, increasing depression risk following stressful life events occurring throughout the lifespan. Some evidence suggests hypothalamic-pituitary-adrenal (HPA) axis-related and serotonergic genetic variation moderates this effect, in a "gene-by-environment-by-environment" interaction (G × E × E). However, prior research has tested single genetic variants, limiting power. The current study uses a multilocus genetic profile score (MGPS) approach to capture polygenic risk relevant to HPA axis and serotonergic functioning. Adolescents (N = 241, Mage = 15.90) completed contextual-threat-based interviews assessing childhood adversity and acute life events, and diagnostic interviews assessing depression. Established MGPSs indexed genetic variation linked to HPA axis (10 single nucleotide polymorphisms [SNPs]) and serotonergic (five SNPs) functioning. Results showed significant MGPS × Childhood Adversity × Recent Life Stress interactions predicting depression for both HPA axis and serotonergic MGPSs, with both risk scores predicting stronger Childhood Adversity × Recent Stress interactions. Serotonergic genetic risk specifically predicted sensitization to major interpersonal stressors. The serotonergic MGPS G × E × E was re-tested in an independent replication sample of early adolescent girls, with comparable results. Findings support the notion that genetic variation linked to these two neurobiological symptoms alters stress sensitization, and that gene-by-environment (G × E) interactions may be qualified by environmental exposures occurring at different points in development.

Interpersonal childhood adversity and stress generation in adolescence: Moderation by HPA axis multilocus genetic variation

Research suggests that childhood adversity (CA) is associated with a wide range of repercussions, including an increased likelihood of interpersonal stress generation. This may be particularly true following interpersonal childhood adversity (ICA) and for youth with high hypothalamic-pituitary-adrenal (HPA) axis-related genetic risk. In the current study, we applied a multilocus genetic profile score (MGPS) approach to measuring HPA axis-related genetic variation and examined its interaction with ICA to predict interpersonal stress generation in a sample of adolescents aged 14–17 (N = 241, Caucasian subsample n = 192). MGPSs were computed using 10 single nucleotide polymorphisms from HPA axis-related genes (CRHR1, NRC31, NRC32, and FKBP5). ICA significantly predicted greater adolescent interpersonal dependent stress. Additionally, MGPS predicted a stronger association between ICA and interpersonal dependent (but not independent or noninterpersonal dependent) stress. No gene–environment interaction (G×E) effects were found for noninterpersonal CA and MGPS in predicting adolescent interpersonal dependent stress. Effects remained after controlling for current depressive symptoms and following stratification by race. Findings extend existing G×E research on stress generation to HPA axis-related genetic variation and demonstrate effects specific to the interpersonal domain.

HPA-axis multilocus genetic variation moderates associations between environmental stress and depressive symptoms among adolescents

Research suggests that genetic variants linked to hypothalamic-pituitary-adrenal (HPA)-axis functioning moderate the association between environmental stressors and depression, but examining gene–environment interactions with single polymorphisms limits power. The current study used a multilocus genetic profile score (MGPS) approach to measuring HPA-axis–related genetic variation and examined interactions with acute stress, chronic stress, and childhood adversity (assessed using contextual threat interview methods) with depressive symptoms as outcomes in an adolescent sample (ages 14–17, N = 241; White subsample n = 192). Additive MGPSs were calculated using 10 single nucleotide polymorphisms within HPA-axis genes (CRHR1, NR3C2, NR3C1, FKBP5). Higher MGPS directly correlated with adolescent depressive symptoms. Moreover, MGPS predicted stronger associations between acute and chronic stress and adolescent depressive symptoms and also moderated the effect of interpersonal, but not noninterpersonal, childhood adversity. Gene–environment interactions individually accounted for 5%–8% of depressive symptom variation. All results were retained following multiple test correction and stratification by race. Results suggest that using MGPSs provides substantial power to examine gene–environmental interactions linked to affective outcomes among adolescents.