Polymorphic variation in the dopamine D4 receptor predicts delay discounting as a function of childhood socioeconomic status: evidence for differential susceptibility.

Inconsistent or null findings among studies associating behaviors on the externalizing spectrum--addictions, impulsivity, risk-taking, novelty-seeking traits--with presence of the 7-repeat allele of a common length polymorphism in the gene encoding the dopamine D4 receptor (DRD4) may stem from individuals' variable exposures to prominent environmental moderators (gene × environment interaction). Here, we report that relative preference for immediate, smaller rewards over larger rewards delayed in time (delay discounting), a behavioral endophenotype of impulsive decision-making, varied by interaction of DRD4 genotype with childhood socioeconomic status (SES) among 546 mid-life community volunteers. Independent of age, sex, adulthood SES and IQ, participants who were both raised in families of distinctly low SES (low parental education and occupational grade) and carried the DRD4 7-repeat allele discounted future rewards more steeply than like-reared counterparts of alternate DRD4 genotype. In the absence of childhood socioeconomic disadvantage, however, participants carrying the 7-repeat allele discounted future rewards less steeply. This bidirectional association of DRD4 genotype with temporal discounting, conditioned by participants' early life circumstances, accords with a recently proposed developmental model of gene × environment interaction ('differential susceptibility') that posits genetically modulated sensitivity to both adverse and salubrious environmental influences.

Using the Children's Depression Inventory in youth with inflammatory bowel disease: support for a physical illness-related factor.

The objective of the present investigation was to evaluate the factor structure of the Children's Depression Inventory (CDI) in adolescents with inflammatory bowel disease (IBD) to better understand the CDI's psychometric properties in a medically complicated population. An exploratory factor analysis was performed on CDI data collected from a clinical sample of 191 youth with IBD, aged 11 to 17 years. Exploratory factor analysis with quartimax rotation yielded 3 factors: mood, behavioral/motivational, and somatic complaints. Only the somatic factor (ie, fatigue, sleep, decreased appetite, and worry about aches and pain) showed a significant positive correlation with IBD severity. The CDI holds promise as a brief measure for the assessment of depressive features psychometrically independent of IBD severity and common steroid treatments as well as of nongastrointestinal specific somatic complaints in a sample of adolescents with IBD. Continued work in this area of research appears promising in honing the assessment of depressive and somatic symptoms in youths with IBD.

Synthesis and characterization of carbon nanotube-polymer multilayer structures.

We develop lightweight, multilayer materials composed of alternating layers of poly dimethyl siloxane (PDMS) polymer and vertically aligned carbon nanotube (CNT) arrays, and characterize their mechanical response in compression. The CNT arrays used in the assembly are synthesized with graded mechanical properties along their thickness, and their use enables the creation of multilayer structures with low density (0.12-0.28 g/cm(3)). We test the mechanical response of structures composed of different numbers of CNT layers partially embedded in PDMS polymer, under quasi-static and dynamic loading. The resulting materials exhibit a hierarchical, fibrous structure with unique mechanical properties: They can sustain large compressive deformations (up to ∼0.8 strain) with a nearly complete recovery and present strain localization in selected sections of the materials. Energy absorption, as determined by the hysteresis observed in stress-strain curves, is found to be at least 3 orders of magnitude larger than that of natural and synthetic cellular materials of comparable density. Conductive bucky paper is included within the polymer interlayers. This allows the measurement of resistance variation as a function of applied stress, showing strong correlation with the observed strain localization in compression.

Reported early family environment covaries with menarcheal age as a function of polymorphic variation in estrogen receptor-α.

Age at menarche, a sentinel index of pubertal maturation, was examined in relation to early family relationships (conflict, cohesion) and polymorphic variation in the gene encoding estrogen receptor-α (ESR1) in a midlife sample of 455 European American women. Consistent with prior literature, women who reported being raised in families characterized by close interpersonal relationships and little conflict tended to reach menarche at a later age than participants reared in families lacking cohesion and prone to discord. Moreover, this association was moderated by ESR1 variation, such that quality of the family environment covaried positively with menarcheal age among participants homozygous for minor alleles of the two ESR1 polymorphisms studied here (rs9304799, rs2234693), but not among women of other ESR1 genotypes. In addition, (a) family relationship variables were unrelated to ESR1 variation, and (b) genotype-dependent effects of childhood environment on age at menarche could not be accounted for by personality traits elsewhere shown to explain heritable variation in reported family conflict and cohesion. These findings are consistent with theories of differential susceptibility to environmental influence, as well as the more specific hypothesis (by Belsky) that girls differ genetically in their sensitivity to rearing effects on pubertal maturation.

Parental education predicts corticostriatal functionality in adulthood.

Socioeconomic disadvantage experienced in early development predicts ill health in adulthood. However, the neurobiological pathways linking early disadvantage to adult health remain unclear. Lower parental education-a presumptive indicator of early socioeconomic disadvantage-predicts health-impairing adult behaviors, including tobacco and alcohol dependencies. These behaviors depend, in part, on the functionality of corticostriatal brain systems that 1) show developmental plasticity and early vulnerability, 2) process reward-related information, and 3) regulate impulsive decisions and actions. Hence, corticostriatal functionality in adulthood may covary directly with indicators of early socioeconomic disadvantage, particularly lower parental education. Here, we tested the covariation between parental education and corticostriatal activation and connectivity in 76 adults without confounding clinical syndromes. Corticostriatal activation and connectivity were assessed during the processing of stimuli signaling monetary gains (positive feedback [PF]) and losses (negative feedback). After accounting for participants' own education and other explanatory factors, lower parental education predicted reduced activation in anterior cingulate and dorsomedial prefrontal cortices during PF, along with reduced connectivity between these cortices and orbitofrontal and striatal areas implicated in reward processing and impulse regulation. In speculation, adult alterations in corticostriatal functionality may represent facets of a neurobiological endophenotype linked to socioeconomic conditions of early development.

Profile of depression in adolescents with inflammatory bowel disease: implications for treatment.

BACKGROUND: The purpose was to determine the utility of including neurovegetative symptoms in assessments of depression in youth with inflammatory bowel disease (IBD). METHODS: Forty-one youth with IBD and concurrent depressive symptomatology were enrolled in an intervention trial and received either 9 modules of cognitive-behavioral therapy (PASCET-PI) or treatment as usual (TAU). Youth and their primary caregivers completed the Children's Depression Inventory (CDI) at pre- (T1) and posttreatment (T2). Disease severity measures and current steroid dosage were obtained at each timepoint. Change in the individual items of the CDI was compared across groups and examined in association with change in physical illness course. RESULTS: Paired sample t-tests revealed significant changes in CDI item scores from T1 to T2 for a majority of the depressive symptoms assessed in the PASCET-PI group, but not for the TAU group. These changes did not appear to be linked to changes in disease severity and/or steroid dosage across these same timepoints. CONCLUSIONS: The inclusion of somatic items in the assessment of depression in physically ill youth is important, as these symptoms seem to respond to psychotherapeutic intervention. The present results would suggest that improvements in depressive symptomatology are not solely related to improvements in the course of IBD and that these items do reflect an important part of the profile of depressive symptoms in youth with IBD. Future research is warranted to replicate present findings and explore the generalizability of these results to other pediatric illness populations.