Faculty Bibliography

Adolescents' propensity for risk-taking and reward-seeking behaviors suggests a heightened sensitivity for reward, reflected by greater feedback-related activity changes in reward circuitry (e.g., nucleus accumbens), and/or a lower sensitivity to potential harm reflected by weaker feedback-related activity changes in avoidance circuitry (e.g., amygdala) relative to adults. Responses of nucleus accumbens and amygdala to valenced outcomes (reward receipt and reward omission) were assayed using an event-related functional magnetic resonance imaging procedure paired with a monetary reward task in 14 adults and 16 adolescents. Bilateral amygdala and nucleus accumbens showed significantly greater activation when winning than when failing to win in both groups. Group comparisons revealed stronger activation of left nucleus accumbens by adolescents, and of left amygdala by adults. When examining responses to reward receipts and to reward omissions separately, the most robust group difference was within the amygdala during reward omission. The reduction of the fMRI BOLD signal in the amygdala in response to reward omission was larger for adults than for adolescents. Correlations showed a close link between negative emotion and amygdala decreased BOLD signal in adults, and between positive emotion and nucleus accumbens activation in adolescents. Overall, these findings support the notion that the signal differences between positive and negative outcomes involve the nucleus accumbens more in adolescents than in adults, and the amygdala more in adults than in adolescents. These developmental differences, if replicated, may have important implications for the development of early-onset disorders of emotion and motivation.

BACKGROUND: Significant controversy has emerged concerning pediatric anxiety disorders. Some researchers question the justification for diagnosing and treating pediatric anxiety disorders, owing to concerns about the inappropriate medicalization of social problems. Others note the importance of diagnosis and treatment, given that pediatric anxiety disorders represent a strong risk factor for serious adult mental disorders. We examine the neural correlates of pediatric anxiety disorders, to consider the validity of the categorization scheme used in recent treatment studies. METHODS: Using inclusion criteria derived from recent treatment trials, we compared gray matter volume throughout the brain in children with and without anxiety. Morphometric analyses used optimized voxel-based morphometry, an automated method for examining structural changes throughout the brain. RESULTS: Reductions in left amygdala gray matter volume were noted for patients with anxiety disorders relative to comparison subjects. CONCLUSIONS: We discuss implications of these findings for current controversies

OBJECTIVE: Attention-deficit/hyperactivity disorder (ADHD) is often accompanied by clinically significant anxiety, but few empirical data guide treatment of children meeting full DSM-IV criteria for ADHD and anxiety disorders (ADHD/ANX). This study examined the efficacy of sequential pharmacotherapy for ADHD/ANX children. METHOD: Children, age 6 to 17 years, with ADHD/ANX were titrated to optimal methylphenidate dose and assessed along with children who entered the study on a previously optimized stimulant. Children with improved ADHD who remained anxious were randomly assigned to 8 weeks of double-blind stimulant + fluvoxamine (STIM/FLV) or stimulant + placebo (STIM/PL). Primary efficacy measures were the Swanson, Nolan, Atkins, and Pelham IV Parent and Teacher Rating Scale ADHD score and the Pediatric Anxiety Rating Scale total score. ADHD, ANX, and overall Clinical Global Impressions-Improvement scores were also obtained. RESULTS: Of the 32 medication-naive children openly treated with methylphenidate, 26 (81%) improved as to ADHD. Twenty-five children entered the randomized trial. Intent-to-treat analysis indicated no differences between the STIM/FLV (n = 15) and STIM/PL groups on the Pediatric Anxiety Rating Scale or Clinical Global Impressions-Improvement-defined responder rate. Medications in both arms were well tolerated. CONCLUSIONS: Children with ADHD/ANX have a response rate to stimulants for ADHD that is comparable with that of children with general ADHD. The benefit of adding FLV to stimulants for ANX remains unproven

Stimulant medication and behavioral treatments are evidence-based for children with attention-deficit/hyperactivity disorder, but the combination of the 2 treatments has been understudied. In this investigation, methylphenidate (MPH) was crossed with 2 levels of behavior modification (BMOD) in a summer treatment program. Twenty-seven children with attention-deficit/hyperactivity disorder, aged 6-12, participated. Children received placebo and 3 doses of transdermal MPH (12.5 cm(2), 25.0 cm(2), and 37.5 cm(2)). BMOD was implemented on alternating weeks. Both treatments produced large and significant effects. Combined treatment was superior to either treatment alone. The effects of transdermal MPH were comparable to those found in this setting in previous studies with multiple stimulant medications and formulations. Consistent with other research, low doses of MPH--even lower than in previous studies--yielded enhanced effects in combination with behavior modification.

It has been known for some time that brain-derived neurotrophic factor (BDNF) is critical to normal development of the CNS, and more recently, studies also have documented the ability of BDNF to modify adult CNS structure and function. Therefore, it is no surprise that BDNF has been linked to diseases, such as epilepsy, which may involve abnormal cortical development or altered brain structure and function after maturity. This review evaluates the evidence, particularly from recent studies, that BDNF contributes to the development of temporal lobe epilepsy (TLE)

Adult dentate neurogenesis is important for certain types of hippocampal-dependent learning and also appears to be important for the maintenance of normal mood and the behavioural effects of antidepressants. Neuropeptide Y (NPY), a peptide neurotransmitter released by interneurons in the dentate gyrus, has important effects on mood, anxiety-related behaviour and learning and memory. We report that adult NPY receptor knock-out mice have significantly reduced cell proliferation and significantly fewer immature doublecortin-positive neurons in the dentate gyrus. We also show that the neuroproliferative effect of NPY is dentate specific, is Y1-receptor mediated and involves extracellular signal-regulated kinase (ERK)1/2 activation. NPY did not exhibit any effect on cell survival in vitro but constitutive loss of the Y1 receptor in vivo resulted in greater survival of newly generated neurons and an unchanged total number of dentate granule cells. These results show that NPY stimulates neuronal precursor proliferation in the dentate gyrus and suggest that NPY-releasing interneurons may modulate dentate neurogenesis

BACKGROUND: Although a large body of evidence suggests a role for the opioid system in alcoholism, the precise role of mu-, delta-, kappa-, and ORL1-opioid receptors and the physiological significance of their natural genetic variation have not been identified. The method of targeted gene disruption by homologous recombination has been used to knock out (KO) genes coding for opioid receptors, and study their effects on alcohol self-administration. Here we examined the effects of targeted disruption of kappa-opioid receptor (KOR) on oral alcohol self-administration and other behaviors. METHODS: Oral alcohol, saccharin and quinine self-administration was assessed in a two-bottle choice paradigm using escalating concentrations of alcohol, or tastant solutions. In preference tests 12% alcohol, 0.033% and 0.066% saccharin, and 0.03 mM and 0.1 mM quinine solutions were used. Open-field activity was determined in an arena equipped with a computer-controlled activity-detection system. Subjects were tested for three consecutive days. Locomotor activity was assessed on days 1 and 2 (after saline injection, i.p.) and on day 3 (after alcohol injection, i.p.). Alcohol-induced locomotor activity was determined as the difference in activity between day 3 and day 2. RESULTS: Male KOR KO mice in preference tests with 12% alcohol consumed about half as much alcohol as wild-type (WT) or heterozygous (HET) mice, showed lower preference for saccharin (0.033% and 0.066%) and higher preference to quinine (0.1 mM) than WT mice. Female KOR KO mice showed similar reduction in alcohol consumption in comparison to WT and HET mice. Partial deletion of KOR in HET mice did not change alcohol consumption in comparison to WT mice. In all genotype-groups females drank significantly more alcohol than males. MANOVA of locomotor activity among KO, WT, and HET mice indicated that strain and sex effects were not significant for alcohol-induced activation (p > 0.05), while strain x sex interaction effects on alcohol-induced activation could be detected (F(1,55) = 6.07, p < 0.05). CONCLUSION: Our results indicating decreased alcohol consumption, lower saccharin preference, and higher quinine preference in KOR KO mice are in line with previous observations of opioid involvement in maintenance of food intake and raise the possibility that the deficient dynorphin/KOR system affects orosensory reward through central mechanisms which reduce alcohol intake and disrupt tastant responses, either as direct effects of absence of kappa-opioid receptors, or as effects of indirect developmental compensatory changes

BACKGROUND: Boys with attention deficit/hyperactivity disorder (AD/HD) demonstrate disruptive behaviour at significantly higher rates compared to girls. Disruptive behaviour often develops as a result of negative interaction patterns within the caregiving relationship. Given the importance of parental cognitions as mediators of parental behaviour, the consideration of parent and child sex in the investigation of causal attributions regarding AD/HD may, at least partially, explain sex differences in the prevalence of disruptive behaviour among children with AD/HD. AIM: To examine the effect of parent and child sex on parental causal attributions and reactions about AD/HD and to investigate the interrelationships between these variables. SAMPLE: Three hundred and seventeen mothers and 317 fathers of boys and girls aged 4-6 years and enrolled in kindergartens in Athens. METHOD: A Greek version of the Parental Account of the Causes of Childhood Problems Questionnaire was used, which followed a vignette about a hypothetical child displaying symptoms of AD/HD. Half of the participants received a male and another half received a female version of the vignette. RESULTS: The child's sex greatly influenced parents' causal attributions about AD/HD. Higher ratings of intentionality were conferred to boys with AD/HD than girls and these attributions were related to stricter responses towards boys. In contrast, parents who considered biological dysfunction as underlying AD/HD, they mostly did so in the case of girls. Minimal effect of parent sex on causal attributions was found. CONCLUSIONS: Because causal attributions of intentionality relate to the response of more strictness and such attributions are more prevalent for boys than girls, then these perceptions about the aetiology of AD/HD in boys may be at the basis of negative interaction patterns. The increase of such interaction patterns may place boys at a more vulnerable position towards the development of secondary behaviour problems