Marilyn J. Essex

How and Why Criteria Defining Moderators and Mediators Differ Between the Baron & Kenny and MacArthur Approaches

OBJECTIVE In recognition of the increasingly important role of moderators and mediators in clinical research, clear definitions are sought of the two terms to avoid inconsistent, ambiguous, and possibly misleading results across clinical research studies. DESIGN The criteria used to define moderators and mediators proposed by the Baron & Kenny approach, which have been long used in social/behavioral research, are directly compared to the criteria proposed by the recent MacArthur approach, which modified the Baron & Kenny criteria. RESULTS After clarifying the differences in criteria between approaches, the rationale for the modifications is clarified and the implications for the design and interpretation of future studies considered. CONCLUSIONS Researchers may find modifications introduced in the MacArthur approach more appropriate to their research objectives, particularly if their research might have a direct influence on decision making.

Revealing the Relation between Temperament and Behavior Problem Symptoms by Eliminating Measurement Confounding: Expert Ratings and Factor Analyses

This study examined the hypothesis that item overlap, or measurement confounding, accounts for the correlation between temperament and behavior problem symptoms in children. First, a conceptual approach was taken in which 41 experts rated temperament (Childrens Behavior Questionnaire, CBQ) and behavior problem symptom items (Preschool Behavior Questionnaire, PBQ) for their fit to both constructs. With this approach, 10% of temperament and 38% of symptom items were confounded. Second, an empirical approach was taken and CBQ and PBQ items were factor analyzed with data from a multi-informant longitudinal study of 451 children. Using this method, 9% of temperament and 23% of symptom items were confounded. Most importantly, removing the confounded items from the CBQ and PBQ scales did not affect the relation between temperament and symptoms, suggesting that the associations were not due to measurement confounding. In addition, the predictive power of earlier temperament for DSM-IV symptoms (Health and Behavior Questionnaire) remained high with the purified CBQ scale. The findings of this study contribute to the understanding of the relation between normal-range temperament and extreme behavior.

MATERNITY LEAVE AND WOMEN'S MENTAL HEALTH

The Wisconsin Maternity Leave and Health Study addresses an important policy issue, parental leave, by investigating the work status, maternity leave, and mental health of 570 women. In the longitudinal design, the women, all of whom were living with a husband or partner, were interviewed during the fifth month of pregnancy, 1 month postpartum, and 4 months postpartum. At 4 months postpartum, full-time workers, part-time workers, and homemakers did not differ in depression or anger, but full-time workers showed elevated anxiety compared with the other two groups. In multiple regression analyses, length of leave interacted significantly with marital concerns when predicting depression; women who took a short leave (6 weeks or less) and were high on marital concerns had the highest depression scores. Short maternity leave can be conceptualized as a risk factor that, when combined with other risk factors such as marital concerns, places women at greater risk for depression.

The Confluence of Mental, Physical, Social, and Academic Difficulties in Middle Childhood. II: Developing the MacArthur Health and Behavior Questionnaire

OBJECTIVES (1) To evaluate the psychometric properties of the MacArthur Health and Behavior Questionnaire (HBQ) in two studies of 4- to 8-year-old children and (2) to explore the empirical and theoretical implications of HBQ-based study findings. METHOD Samples of children were recruited from (1) mental health clinics (n = 53) and community schools (n = 67) for a case-control study in three research sites and (2) a Wisconsin-based community cohort study of families and work, comprising children with high levels of internalizing and/or externalizing behavior problems and asymptomatic children (N = 122). Combinations of mothers, fathers, and teachers completed the HBQ at one or two time points in four geographically and culturally distinctive settings. RESULTS Assessment of HBQ reliability showed high test-retest stability and cross-informant agreement. The instrument discriminated strongly and significantly among symptom groups (i.e., high internalizing, high externalizing, high both, and low both) and showed moderate to large effect sizes for between-group differences. Substantial covariance was also found among the HBQ mental, physical, social, and academic problem subscales. CONCLUSIONS The HBQ is a reliable and valid parent- and teacher-report instrument for assessing multiple dimensions of health and dysfunction in middle childhood and for identifying children on whom more intensive diagnostic procedures may be warranted. Confluences among the four health dimensions suggest phenomenological and perhaps etiological commonalities among traditionally partitioned childhood difficulties and suggest possible artificiality in the conventional distinction between pediatric and child psychiatric morbidities.

Concurrent and longitudinal associations of basal and diurnal cortisol with mental health symptoms in early adolescence

Recent biosocial theories postulate that both biological risk and the social context influence the development of mental health problems [Boyce and Ellis (2005) Development and Psychopathology, 17(2), 271-301]. Guided by this framework, we examined whether basal cortisol and its diurnal rhythm were associated with mental health symptoms in early adolescence. Because cross-sectional and longitudinal investigations sometimes reveal different cortisol-mental health associations, we examined the association both concurrently and longitudinally when children transition to middle school, a time which entails a major change in social context from single to multiple teachers, classrooms, and sets of classmates. Salivary cortisol was measured three times a day (waking, afternoon, and bedtime) across 3 days when adolescents were 5th graders. Mental health was measured when adolescents were in 5th and 7th grades, just before and after the transition to middle school. To deal with the substantial comorbidity of internalizing and externalizing symptoms at this developmental stage, mental health measures distinguished overall symptom severity from the preponderance of internalizing versus externalizing symptoms (i.e., directionality). A three-level Hierarchical Linear Model was used to extract basal cortisol and its diurnal rhythm separate from the day-to-day and within-the-day fluctuations in cortisol in response to daily experiences. Results were specific to symptom severity, suggesting that cortisol is a nonspecific risk factor for mental health symptoms in young adolescents. At 5th grade, low basal cortisol was associated with concurrent symptom severity. However, longitudinally, it was adolescents with high cortisol at 5th grade who were at risk for increasing mental health symptoms by 7th grade. Flat diurnal rhythms in 5th grade were related to levels of symptom severity at both 5th and 7th grades. Considering the change in social context, as defined by the transition to middle school, helped resolve seemingly inconsistent evidence that both hypo- and hyper-arousal were associated with mental health symptoms in early adolescence.

Early Risk Factors and Developmental Pathways to Chronic High Inhibition and Social Anxiety Disorder in Adolescence

OBJECTIVE Evidence suggests that chronic high levels of behavioral inhibition are a precursor of social anxiety disorder. The authors sought to identify early risk factors for, and developmental pathways to, chronic high inhibition among school-age children and the association of chronic high inhibition with social anxiety disorder by adolescence. METHOD A community sample of 238 children was followed from birth to grade 9. Mothers, teachers, and children reported on the childrens behavioral inhibition from grades 1 to 9. Lifetime history of psychiatric disorders was available for the subset of 60 (25%) children who participated in an intensive laboratory assessment at grade 9. Four early risk factors were assessed: female gender; exposure to maternal stress during infancy and the preschool period; and at age 4.5 years, early manifestation of behavioral inhibition and elevated afternoon salivary cortisol levels. RESULTS All four risk factors predicted greater and more chronic inhibition from grades 1 to 9, and together they defined two developmental pathways. The first pathway, in girls, was partially mediated by early evidence of behavioral inhibition and elevated cortisol levels at age 4.5 years. The second pathway began with exposure to early maternal stress and was also partially mediated by childhood cortisol levels. By grade 9, chronic high inhibition was associated with a lifetime history of social anxiety disorder. CONCLUSIONS Chronic high levels of behavioral inhibition are associated with social anxiety disorder by adolescence. The identification of two developmental pathways suggests the potential importance of considering both sets of risk factors in developing preventive interventions for social anxiety disorder.

Childhood maltreatment is associated with altered fear circuitry and increased internalizing symptoms by late adolescence

Significance Childhood maltreatment is a major risk factor for internalizing disorders including depression and anxiety, which cause significant disability. Altered connectivity of the brain’s fear circuitry represents an important candidate mechanism linking maltreatment and these disorders, but this relationship has not been directly explored. Using resting-state functional brain connectivity in adolescents, we show that maltreatment predicts lower prefrontal–hippocampal connectivity in females and males but lower prefrontal–amygdala connectivity only in females. Altered connectivity, in turn, mediated the development of internalizing symptoms. These results highlight the importance of fronto–hippocampal connectivity for both sexes in internalizing symptoms following maltreatment. The additional impact on fronto–amygdala connectivity in females may help explain their higher risk for anxiety and depression. Maltreatment during childhood is a major risk factor for anxiety and depression, which are major public health problems. However, the underlying brain mechanism linking maltreatment and internalizing disorders remains poorly understood. Maltreatment may alter the activation of fear circuitry, but little is known about its impact on the connectivity of this circuitry in adolescence and whether such brain changes actually lead to internalizing symptoms. We examined the associations between experiences of maltreatment during childhood, resting-state functional brain connectivity (rs-FC) of the amygdala and hippocampus, and internalizing symptoms in 64 adolescents participating in a longitudinal community study. Childhood experiences of maltreatment were associated with lower hippocampus–subgenual cingulate rs-FC in both adolescent females and males and lower amygdala–subgenual cingulate rs-FC in females only. Furthermore, rs-FC mediated the association of maltreatment during childhood with adolescent internalizing symptoms. Thus, maltreatment in childhood, even at the lower severity levels found in a community sample, may alter the regulatory capacity of the brain’s fear circuit, leading to increased internalizing symptoms by late adolescence. These findings highlight the importance of fronto–hippocampal connectivity for both sexes in internalizing symptoms following maltreatment in childhood. Furthermore, the impact of maltreatment during childhood on both fronto–amygdala and –hippocampal connectivity in females may help explain their higher risk for internalizing disorders such as anxiety and depression.

Predictors, prodromes and incidence of postpartum depression

The purpose of this study was to determine the incidence of clinically significant depression occurring between 7 and 4 months postpartum and to investigate whether somatic complaints, subsyndromal depressive symptoms, or birth-related concerns among non-depressed women at 1 month were predictive of postpartum depression. This is a prospective cohort study of 465 women from the Wisconsin Maternity Leave and Health Project (WMLHP). Women who were not depressed at 1 month postpartum were reassessed 3 months later for depression occurring at any time in the interval between 1 and 4 months postpartum. Depression was defined as either meeting the criteria for major depression on the National Institute of Mental Health (NIMH) Diagnostic Interview Schedule (DIS) or scoring above 15 on the Center for Epidemiologic Studies Depression Scale (CES-D). Physical symptoms were assessed by an adapted Health Responses Scale. Other measures were developed specifically for the WMLHP. Of 465 women, 27 (5.8%) became clinically depressed between 1 and 4 months postpartum. In a logistic regression analysis, four variables (maternal age, depression during pregnancy, thoughts of death and dying at 1 month postpartum, and difficulty falling asleep at 1 month postpartum) were predictive of depression at 4 months postpartum. Breast-feeding, mode of delivery, family income, parity and mother‘s education did not predict depression. The existence of subsyndromal depressive symptoms, particularly thoughts of death and dying, may represent a prodromal phase of depression and should alert clinicians to the possibility of future postpartum depression. Women with a history of depression during pregnancy should be monitored for signs of postpartum depression for a minimum of 4 months. Obstetricians are in a unique position during the postpartum check-up to screen women for these predictors of future postpartum depression and possibly to avert the development of a clinically significant depressive episode.

Longitudinal stability and developmental properties of salivary cortisol levels and circadian rhythms from childhood to adolescence.

This study aimed to (1) identify a stable, trait-like component to cortisol and its circadian rhythm, and (2) investigate individual differences in developmental trajectories of HPA-axis maturation. Multiple salivary cortisol samples were collected longitudinally across four assessments from age 9 (3rd grade) through age 15 (9th grade) in a community sample of children (N = 357). Sophisticated statistical models examined cortisol levels and its rhythm over time; effects of age, puberty and gender were primarily considered. In addition to situation-specific and stable short-term or epoch-specific cortisol components, there is a stable, trait-like component of cortisol levels and circadian rhythm across multiple years covering the transition from childhood into adolescence. Youth had higher cortisol and flatter circadian rhythms as they got older and more physically developed. Girls had higher cortisol, stronger circadian rhythms, and greater developmental influences across adolescence. Distinguishing a stable, trait-like component of cortisol level and its circadian rhythm provides the empirical foundation for investigating putative mechanisms underlying individual differences in HPA functioning. The findings also provide important descriptive information about maturational processes influencing HPA-axis development.

Influence of early life stress on later hypothalamic–pituitary–adrenal axis functioning and its covariation with mental health symptoms: A study of the allostatic process from childhood into adolescence

The hypothalamic-pituitary-adrenal (HPA) axis is a primary mechanism in the allostatic process through which early life stress (ELS) contributes to disease. Studies of the influence of ELS on childrens HPA axis functioning have yielded inconsistent findings. To address this issue, the present study considers multiple types of ELS (maternal depression, paternal depression, and family expressed anger), mental health symptoms, and two components of HPA functioning (traitlike and epoch-specific activity) in a long-term prospective community study of 357 children. ELS was assessed during the infancy and preschool periods; mental health symptoms and cortisol were assessed at child ages 9, 11, 13, and 15 years. A three-level hierarchical linear model addressed questions regarding the influences of ELS on HPA functioning and its covariation with mental health symptoms. ELS influenced traitlike cortisol level and slope, with both hyper- and hypoarousal evident depending on type of ELS. Further, type(s) of ELS influenced covariation of epoch-specific HPA functioning and mental health symptoms, with a tighter coupling of HPA alterations with symptom severity among children exposed previously to ELS. Results highlight the importance of examining multiple types of ELS and dynamic HPA functioning in order to capture the allostatic process unfolding across the transition into adolescence.