Faculty Bibliography

The authors examined racial/ethnic disparities in mental health service use based on problem type (internalizing/externalizing). A diverse sample of youth in contact with public sectors of care and their families provided reports of youth's symptoms and functional impairment during an initial interview. Specialty and school-based mental health service use during the subsequent 2 years was assessed prospectively. Greater disparities in mental health service receipt were evident for internalizing problems, with non-Hispanic White youth more likely to receive services in response to internalizing symptoms than minority youth. Fewer disparities in rates of unmet need emerged for externalizing problems, but minority youth were more likely to have need for externalizing problems met and African American youth were particularly likely to receive services in response to such problems. Findings highlight the importance of considering problem type when examining racial disparities in mental health services and underscore concerns about the responsiveness of mental health services for minority youth with internalizing disorders.

BACKGROUND: Childhood adversity has been shown to interact with monoamine oxidase-A (MAOA) genotype to confer risk for antisocial behavior. Studies examining this gene-by-environment (G x E) association, however, have produced mixed results. METHODS: Relevant research is reviewed, and results of a study with 114 children (73 maltreated and 41 control subjects) are presented. The maltreated children represent the extreme on a continuum of adversity and were assessed at a time of extreme stress-shortly after removal from their parents' care due to abuse. Measures of aggressive behavior were obtained using standard research instruments, and monoamine oxidase-A MAOA genotypes were obtained from saliva-derived DNA specimens. Population structure was controlled for using ancestral proportion scores computed on the basis of genotypes of ancestry informative markers. RESULTS: Many prior investigations appear to have had reduced power to detect the predicted G x E interaction because of low base rates of maltreatment and antisocial behavior in their samples and failure to use optimal procedures to control for population structure in ethnically diverse cohorts. In this investigation, a significant interaction was detected between exposure to moderate trauma and the 'low-activity' MAOA genotype in conferring risk for aggression. Children with exposure to extreme levels of trauma, however, had high aggression scores regardless of genotype. CONCLUSIONS: Our study suggests that problems in aggressive behavior in maltreated children are moderated by MAOA genotype, but only up to moderate levels of trauma exposure. Extreme levels of trauma appear to overshadow the effect of MAOA genotype, especially in children assessed at time of acute crisis

BACKGROUND: Behaviorally inhibited (BI) children who also exhibit enhanced response monitoring might be at particularly high risk for anxiety disorders. The current study tests the hypothesis that response monitoring, as manifest in the error-related negativity (ERN), moderates the association between BI and anxiety. METHODS: Participants (n=113; 73 male) assessed for early-childhood BI were re-assessed as adolescents with a clinical interview and a flanker paradigm that generated behavioral data and event-related potentials (ERPs). Risk for anxiety disorders in adolescents was examined as a function of childhood-BI status and adolescent performance on the flanker paradigm. RESULTS: Adolescents with childhood BI displayed ERP evidence of enhanced response monitoring, manifest as large ERNs. The ERN moderated the relationship between early BI and later clinically significant disorders. CONCLUSIONS: Physiological measures of response monitoring might moderate associations between early-childhood BI and risk for psychopathology. The subset of children with BI and enhanced response monitoring might face greater risk for later-life clinical anxiety than children with either BI or enhanced response monitoring alone.

Mood, attention and motivation co-vary with activity in the neuromodulatory systems of the brain to influence behaviour. These psychological states, mediated by neuromodulators, have a profound influence on the cognitive processes of attention, perception and, particularly, our ability to retrieve memories from the past and make new ones. Moreover, many psychiatric and neurodegenerative disorders are related to dysfunction of these neuromodulatory systems. Neurons of the brainstem nucleus locus coeruleus are the sole source of noradrenaline, a neuromodulator that has a key role in all of these forebrain activities. Elucidating the factors that control the activity of these neurons and the effect of noradrenaline in target regions is key to understanding how the brain allocates attention and apprehends the environment to select, store and retrieve information for generating adaptive behaviour

The mechanisms underlying off-line consolidation of memory during sleep are elusive. Learning of hippocampus-dependent tasks increases neocortical slow oscillation synchrony, and thalamocortical spindle and hippocampal ripple activity during subsequent non-rapid eye movement sleep. Slow oscillations representing an oscillation between global neocortical states of increased (up-state) and decreased (down-state) neuronal firing temporally group thalamic spindle and hippocampal ripple activity, which both occur preferentially during slow oscillation up-states. Here we examined whether slow oscillations also group learning-induced increases in spindle and ripple activity, thereby providing time-frames of facilitated hippocampus-to-neocortical information transfer underlying the conversion of temporary into long-term memories. Learning (word-pairs in humans, odor-reward associations in rats) increased slow oscillation up-states and, in humans, shaped the timing of down-states. Slow oscillations grouped spindle and rat ripple activity into up-states under basal conditions. Prior learning produced in humans an increase in spindle activity focused on slow oscillation up-states. In rats, learning induced a distinct increase in spindle and ripple activity that was not synchronized to up-states. Event-correlation histograms indicated an increase in spindle activity with the occurrence of ripples. This increase was prolonged after learning, suggesting a direct temporal tuning between ripples and spindles. The lack of a grouping effect of slow oscillations on learning-induced spindles and ripples in rats, together with the less pronounced effects of learning on slow oscillations, presumably reflects a weaker dependence of odor learning on thalamo-neocortical circuitry. Slow oscillations might provide an effective temporal frame for hippocampus-to-neocortical information transfer only when thalamo-neocortical systems are already critically involved during learning

Fetal alcohol syndrome (FAS), a condition occurring in some children of mothers who have consumed alcohol during pregnancy, is characterized by physical deformities and learning and memory deficits. The chick hippocampus, whose functions are controlled by interneurons expressing calcium-binding proteins parvalbumin (PV) and calretinin (CR), is involved in learning and memory mechanisms. Effects on growth and development and hippocampal morphology were studied in chick embryos exposed to 5% and 10% ethanol volume/volume (vol/vol) for 2 or 8 days of gestation. There was a significant dose-dependent reduction (P<.05) in body weight and mean number per section of PV and CR expressing hippocampal neurons in ethanol-exposed chicks, without alterations in neuronal nuclear size or hippocampal volume, compared appropriate controls. Moreover, when chicks exposed to 5% ethanol for 2 and 8 days of gestation were compared, no significant differences were found in body parameters or neuronal counts. Similarly, exposure to 10% ethanol did not induce any significant changes in chicks exposed for 2 or 8 gestational days. Thus, these results suggest that gestational ethanol exposure induces a reduction in the mean number per section of PV and CR expressing hippocampal neurons, and could be a possible mechanism responsible for learning and memory disorders in FAS.

In this review we are concerned specifically with the putative role of the default-mode network (DMN) in the pathophysiology of mental disorders. First, we define the DMN concept with regard to its neuro-anatomy, its functional organisation through low frequency neuronal oscillations, its relation to other recently discovered low frequency resting state networks, and the cognitive functions it is thought to serve. Second, we introduce methodological and analytical issues and challenges. Third, we describe putative mechanisms proposed to link DMN abnormalities and mental disorders. These include interference by network activity during task performance, altered patterns of antagonism between task specific and non-specific elements, altered connectively and integrity of the DMN, and altered psychological functions served by the network DMN. Fourth, we review the empirical literature systematically. We relate DMN dysfunction to dementia, schizophrenia, epilepsy, anxiety and depression, autism and attention deficit/hyperactivity disorder drawing out common and unique elements of the disorders. Finally, we provide an integrative overview and highlight important challenges and tasks for future research

This article summarizes current research related to autism spectrum disorders. Current epidemiological trends, theories about aetiology, and relevant issues in assessment and diagnosis of autism spectrum disorders are discussed