Daniel P. Johnson

Association between Depressive Symptoms and Negative Dependent Life Events from Late Childhood to Adolescence

The association between stressful life events and depression has been consistently supported in the literature; however, studies of the developmental trajectories of these constructs and the nature of their association over time are limited. We examined trajectories of depressive symptoms and negative dependent life events and the associations between these constructs in a sample of 916 youth assessed annually from age 9 to 16, using latent growth curve modeling. Youth depressive symptoms, as rated by youth, parents, and teachers, decreased from late childhood into adolescence, whereas rates of youth-rated life events did not change significantly over time. Initial levels of depressive symptoms were positively associated with initial levels of life events. Furthermore, after controlling for the initial association between the two constructs, increases in depressive symptoms (as assessed by parents and youth) were positively associated with increases in life events over time. The study builds on prior research by focusing specifically on negative dependent life events, examining results across multiple informants, and employing latent growth curve modeling to evaluate associations between trajectories of life events and depressive symptoms in a longitudinal adolescent sample. Additional studies employing latent growth modeling to examine the changes in this association during adolescence are needed.

The Etiology of Observed Negative Emotionality from 14 to 24 Months

We examined the magnitude of genetic and environmental influences on observed negative emotionality at age 14, 20, and 24 months. Participants were 403 same-sex twin pairs recruited from the Longitudinal Twin Study whose emotional responses to four different situations were coded by independent raters. Negative emotionality showed significant consistency across settings, and there was evidence of a latent underlying negative emotionality construct. Heritability decreased, and the magnitude of shared environmental influences increased, for the latent negative emotionality construct from age 14 to 24 months. There were significant correlations between negative emotionality assessed at age 14, 20, and 24 months, and results suggested common genetic and shared environmental influences affecting negative emotionality across age, and that age-specific influences are limited to non-shared environmental influences, which include measurement error.

Genetic and environmental influences on rumination and its covariation with depression

This study examined the extent to which rumination and depression share genetic and environmental influences in a community sample of adult twins (N = 663). Twins completed multiple rumination questionnaires, a depressive symptoms questionnaire and a diagnostic interview. Rumination was moderately heritable (h2 = .37–.41 for the latent variable) and substantially influenced by nonshared environmental factors, and these results were consistent across different measures. Nonshared environmental influences on rumination were larger for women than men. Depressive symptoms and diagnosis were influenced by genetic and nonshared environmental factors (h2 = .30–.45). The genetic correlations between rumination and depression were moderate to large (rA = .40–.82), suggesting that a substantial proportion of the genetic influences on rumination overlap with those on depression. Results were similar when examining self-reported depressive symptoms and interview-based diagnosis of major depressive disorder. These results highlight the importance of rumination in the integration of cognitive and genetic models of depression risk.

Dysfunctional attitudes and the serotonin transporter promoter polymorphism (5-HTTLPR).

Dysfunctional attitudes may be one phenotype by which genes increase risk for depression. Building on research demonstrating associations between serotonin abnormalities and dysfunctional attitudes, we examined the covariation between dysfunctional attitudes and the serotonin transporter gene-linked polymorphic region (5-HTTLPR). In a sample of nondepressed young adults (N=131), people with one or two copies of the low-expressing alleles reported stronger endorsement of dysfunctional attitudes regarding performance evaluation than people who were homozygous for the high-expressing alleles; there was no association between the 5-HTTLPR polymorphism and dysfunctional attitudes regarding approval by others. These results add to the literature linking the 5-HTTLPR polymorphism and cognitive vulnerabilities for depression.

Intimate relationship involvement, intimate relationship quality, and psychiatric disorders in adolescents.

Prior research has shown that poor relationship quality in marriage and other intimate relationships demonstrates cross-sectional and longitudinal associations with a variety of psychiatric disorders in adults. In comparison, there has been less research on the covariation between relationship quality and psychiatric disorders in adolescents, a developmental period that is associated with elevated risk of incidence of several disorders and that is important for the acquisition and maintenance of intimate relationships. The present study was conducted to examine the associations between intimate relationship involvement, intimate relationship quality, and psychiatric disorders in a population-based sample of adolescents. The associations between relationship involvement, positive and negative relationship quality, and 12-month prevalence of mood, anxiety, and substance use disorders were evaluated in adolescents from the National Comorbidity Survey-Adolescent Supplement. Participants completed an interview-based assessment of psychiatric disorders and a self-report measure of relationship quality. Results indicated that the prevalence of broad categories of mood, anxiety, and substance use disorders, and several specific disorders were significantly associated with (a) being married, cohabiting, or involved in a serious relationship; and (b) reporting more negative (but not less positive) relationship quality. For several disorders, the association between the disorder and relationship involvement was moderated by age, wherein the strength of the association decreased in magnitude with increasing age. Findings suggest that being in an intimate relationship and reporting higher levels of negative relationship quality are associated with the prevalence of several common psychiatric disorders in adolescents.

A Behavior Genetic Analysis of Pleasant Events, Depressive Symptoms, and Their Covariation

Although pleasant events figure prominently in behavioral models of depression, little is known regarding characteristics that may predispose people to engage in pleasant events and derive pleasure from these events. The present study was conducted to evaluate genetic and environmental influences on the experience of pleasant events, depressive symptoms, and their covariation in a sample of 148 twin pairs. A multivariate twin modeling approach was used to examine the genetic and environmental covariance of pleasant events and depressive symptoms. Results indicated that the experience of pleasant events was moderately heritable and that the same genetic factors influence both the experience of pleasant events and depressive symptoms. These findings suggest that genetic factors may give rise to dispositional tendencies to experience both pleasant events and depression.

Is Set Shifting Really Impaired in Trait Anxiety? Only When Switching Away From an Effortfully Established Task Set.

The current study investigated whether trait anxiety was systematically related to task-set shifting performance, using a task-switching paradigm in which 1 task was more attentionally demanding than the other. Specifically, taking advantage of a well-established phenomenon known as asymmetric switch costs, we tested the hypothesis that the association between trait anxiety and task-set shifting is most clearly observed when individuals must switch away from a more attentionally demanding task for which it was necessary to effortfully establish an appropriate task set. Ninety-one young adults completed an asymmetric switching task and trait-level mood questionnaires. Results indicated that higher levels of trait anxiety were systematically associated with greater asymmetry in reaction time (RT) switch costs. Specifically, the RT costs for switching from the more attentionally demanding task to the less demanding task were significantly greater with higher levels of trait anxiety, whereas the RT costs for switching in the opposite direction were not significantly associated with trait anxiety levels. Further analyses indicated that these associations were not attributable to comorbid dysphoria or worry. These results suggest that levels of trait anxiety may not be related to general set-shifting ability per se, but, rather, that anxiety-specific effects may primarily be restricted to when one must efficiently switch away from (or let go of) an effortfully established task set.

A Twin Study Examining Rumination as a Transdiagnostic Correlate of Psychopathology

This study examined the genetic and environmental influences on rumination and its associations with several forms of psychopathology in a sample of adult twins (N = 744). Rumination was significantly associated with major depressive disorder, depressive symptoms, generalized anxiety disorder, eating pathology, and substance dependence symptoms. There were distinct patterns of etiological overlap between rumination and each form of psychopathology; rumination had considerable genetic overlap with depression, modest genetic overlap with eating pathology, and almost no genetic overlap with substance dependence. Findings further suggest considerable overlap between genetic and environmental influences on rumination and those contributing to the covariance between forms of psychopathology. Results were specific to ruminative thought and did not extend to self-reflection. These findings support the conceptualization of rumination as a transdiagnostic correlate and risk factor for psychopathology and also suggest that the biological and environmental mechanisms linking rumination to psychopathology may differ depending on the disorder.