https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(08)61706-7.pdf

Burden and consequences of child maltreatment in high-income countries

Evolutionary-biological reasoning suggests that individuals should be differentially susceptible to environmental influences, with some people being not just more vulnerable than others to the negative effects of adversity, as the prevailing diathesis-stress view of psychopathology (and of many environmental influences) maintains, but also disproportionately susceptible to the beneficial effects of supportive and enriching experiences (or just the absence of adversity). Evidence consistent with the proposition that individuals differ in plasticity is reviewed. The authors document multiple instances in which (a) phenotypic temperamental characteristics, (b) endophenotypic attributes, and (c) specific genes function less like “vulnerability factors” and more like “plasticity factors,” thereby rendering some individuals more malleable or susceptible than others to both negative and positive environmental influences. Discussion focuses upon limits of the evidence, statistical criteria for distinguishing differential susceptibility from diathesis stress, potential mechanisms of influence, and unknowns in the differentialsusceptibility equation.

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Beyond Diathesis Stress: Differential Susceptibility to Environmental Influences.

Stress affects cognition and increases noradrenaline and dopamine levels in the prefrontal cortex (PFC). Amy Arnsten discusses the intracellular signalling pathways that mediate the effects of these catecholamines on PFC function during acute and chronic stress, focusing on working memory. An interview with Amy Arnsten for Neuropod is available for
 download
 . The prefrontal cortex (PFC) — the most evolved brain region — subserves our highest-order cognitive abilities. However, it is also the brain region that is most sensitive to the detrimental effects of stress exposure. Even quite mild acute uncontrollable stress can cause a rapid and dramatic loss of prefrontal cognitive abilities, and more prolonged stress exposure causes architectural changes in prefrontal dendrites. Recent research has begun to reveal the intracellular signalling pathways that mediate the effects of stress on the PFC. This research has provided clues as to why genetic or environmental insults that disinhibit stress signalling pathways can lead to symptoms of profound prefrontal cortical dysfunction in mental illness.

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Stress signalling pathways that impair prefrontal cortex structure and function

Review: Following you home from school: A critical review and synthesis of research on cyberbullying victimization

This report builds on a highly valued predecessor, the 1994 Institute of Medicine (IOM) report entitled Reducing Risks for Mental Disorders: Frontiers for Preventive Intervention Research. That report provided the basis for understanding prevention science, elucidating its then-existing research base, and contemplating where it should go in the future. This report documents that an increasing number of mental, emotional, and behavioral problems in young people are in fact preventable. The proverbial ounce of prevention will indeed be worth a pound of cure: effectively applying the evidence-based prevention interventions at hand could potentially save billions of dollars in associated costs by avoiding or tempering these disorders in many individuals. Furthermore, devoting significantly greater resources to research on even more effective prevention and promotion efforts, and then reliably implementing the findings of such research, could substantially diminish the human and economic toll.

Preventing Mental, Emotional, and Behavioral Disorders Among Young People: Progress and Possibilities

Previous research on adults has shown that a functional polymorphism in the promoter region of the monoamine oxidase A (MAOA) gene moderates the impact of childhood maltreatment on risk for developing antisocial behavior. Thus far, attempts to replicate this finding have been mixed. The current study (i) presents new data investigating this finding in a sample of 975 seven-year-old boys, and (ii) evaluates the extant data by conducting a meta-analysis of published findings. We replicated the original finding by showing that the MAOA polymorphism moderates the development of psychopathology after exposure to physical abuse, we extended the finding to childhood closer in time to the maltreatment experience, and we ruled-out the possibility of a spurious finding by accounting for passive and evocative gene-environment correlation. Moreover, meta-analysis demonstrated that across studies, the association between maltreatment and mental health problems is significantly stronger in the group of males with the genotype conferring low vs high MAOA activity. These findings provide the strongest evidence to date suggesting that the MAOA gene influences vulnerability to environmental stress, and that this biological process can be initiated early in life.

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MAOA , maltreatment, and gene–environment interaction predicting children's mental health: new evidence and a meta-analysis

OBJECTIVE. It has been shown that bullying victimization is associated with behavior and school adjustment problems, but it remains unclear whether the experience of bullying uniquely contributes to those problems after taking into account preexisting adjustment problems. METHODS. We examined bullying in the Environmental Risk Study, a nationally representative 1994–1995 birth cohort of 2232 children. We identified children who experienced bullying between the ages of 5 and 7 years either as pure victims or bully/victims. We collected reports from mothers and teachers about children’s behavior problems and school adjustment when they were 5 years old and again when they were age 7. RESULTS. Compared with control children, pure victims showed more internalizing problems and unhappiness at school when they were 5 and 7 years. Girls who were pure victims also showed more externalizing problems than controls. Compared with controls and pure victims, bully/victims showed more internalizing problems, more externalizing problems, and fewer prosocial behaviors when they were 5 and 7 years. They also were less happy at school compared with control children at 7 years of age. Pure victims and bully/victims showed more behavior and school adjustment problems at 7 years of age, even after controlling for preexisting adjustment problems at 5 years of age. CONCLUSIONS. Being the victim of a bully during the first years of schooling contributes to maladjustment in young children. Prevention and intervention programs aimed at reducing mental health problems during childhood should target bullying as an important risk factor.

Bullying Victimization Uniquely Contributes to Adjustment Problems in Young Children: A Nationally Representative Cohort Study

It has been shown that lower birthweight is associated with lower IQ, but it remains unclear whether this association is causal or spurious. We examined the relationship between birthweight and IQ in two prospective longitudinal birth cohorts: a UK cohort of 1116 twin pairs (563 monozygotic [MZ] pairs), born in 1994-95, and a New Zealand cohort of 1037 singletons born in 1972-73. IQ was tested with the Wechsler Intelligence Scales for Children. Birthweight differences within MZ twin pairs predicted IQ differences within pairs, ruling out genetic and shared environmental explanations for the association. Birthweight predicted IQ similarly in the twin and nontwin cohorts after controlling for social disadvantage, attesting that the association generalized beyond twins. An increase of 1000 g in birthweight was associated with a 3 IQ point increase. Results from two cohorts add to evidence that low birthweight is a risk factor for compromised neurological health. Our finding that birthweight differences predict IQ differences within MZ twin pairs provides new evidence that the mechanism can be narrowed to an environmental effect during pregnancy, rather than any familial environmental influence shared by siblings, or genes. With the increasing numbers of low-birthweight infants, our results support the contention that birthweight could be a target for early preventive intervention to reduce the number of children with compromised IQ.

/pdf/birthweight-predicts-iq-fact-or-artefact-4h453vjlqo.pdf

Rhiannon Newcombe

Papers

MAOA , maltreatment, and gene–environment interaction predicting children's mental health: new evidence and a meta-analysis

Bullying Victimization Uniquely Contributes to Adjustment Problems in Young Children: A Nationally Representative Cohort Study

Birthweight predicts IQ: Fact or artefact?