The effects of intranasal oxytocin on reward circuitry responses in children with autism spectrum disorder.

BACKGROUND: Intranasal oxytocin (OT) has been shown to improve social communication functioning of individuals with autism spectrum disorder (ASD) and, thus, has received considerable interest as a potential ASD therapeutic agent. Although preclinical research indicates that OT modulates the functional output of the mesocorticolimbic dopamine system that processes rewards, no clinical brain imaging study to date has examined the effects of OT on this system using a reward processing paradigm. To address this, we used an incentive delay task to examine the effects of a single dose of intranasal OT, versus placebo (PLC), on neural responses to social and nonsocial rewards in children with ASD. METHODS: In this placebo-controlled double-blind study, 28 children and adolescents with ASD (age: M = 13.43 years, SD = 2.36) completed two fMRI scans, one after intranasal OT administration and one after PLC administration. During both scanning sessions, participants completed social and nonsocial incentive delay tasks. Task-based neural activation and connectivity were examined to assess the impact of OT relative to PLC on mesocorticolimbic brain responses to social and nonsocial reward anticipation and outcomes. RESULTS: Central analyses compared the OT and PLC conditions. During nonsocial reward anticipation, there was greater activation in the right nucleus accumbens (NAcc), left anterior cingulate cortex (ACC), bilateral orbital frontal cortex (OFC), left superior frontal cortex, and right frontal pole (FP) during the OT condition relative to PLC. Alternatively, during social reward anticipation and outcomes, there were no significant increases in brain activation during the OT condition relative to PLC. A Treatment Group × Reward Condition interaction revealed relatively greater activation in the right NAcc, right caudate nucleus, left ACC, and right OFC during nonsocial relative to social reward anticipation during the OT condition relative to PLC. Additionally, these analyses revealed greater activation during nonsocial reward outcomes during the OT condition relative to PLC in the right OFC and left FP. Finally, functional connectivity analyses generally revealed changes in frontostriatal connections during the OT condition relative to PLC in response to nonsocial, but not social, rewards. CONCLUSIONS: The effects of intranasal OT administration on mesocorticolimbic brain systems that process rewards in ASD were observable primarily during the processing of nonsocial incentive salience stimuli. These findings have implications for understanding the effects of OT on neural systems that process rewards, as well as for experimental trials of novel ASD treatments developed to ameliorate social communication impairments in ASD.

Adaptive behavior in autism: Minimal clinically important differences on the Vineland-II.

Autism Spectrum Disorder (ASD) is associated with persistent impairments in adaptive abilities across multiple domains. These social, personal, and communicative impairments become increasingly pronounced with development, and are present regardless of IQ. The Vineland Adaptive Behavior Scales, Second Edition (Vineland-II) is the most commonly used instrument for quantifying these impairments, but minimal clinically important differences (MCIDs) on Vineland-II scores have not been rigorously established in ASD. We pooled data from several consortia/registries (EU-AIMS LEAP study, ABIDE-I, ABIDE-II, INFOR, Simons Simplex Collection and Autism Treatment Network [ATN]) and clinical investigations and trials (Stanford, Yale, Roche) resulting in a data set of over 9,000 individuals with ASD. Two approaches were used to estimate MCIDs: distribution-based methods and anchor-based methods. Distribution-based MCID [d-MCID] estimates included the standard error of the measurement, as well as one-fifth and one-half of the covariate-adjusted standard deviation (both cross-sectionally and longitudinally). Anchor-based MCID [a-MCID] estimates include the slope of linear regression of clinician ratings of severity on the Vineland-II score, the slope of linear regression of clinician ratings of longitudinal improvement category on Vineland-II change, the Vineland-II change score maximally differentiating clinical impressions of minimal versus no improvement, and equipercentile equating. Across strata, the Vineland-II Adaptive Behavior Composite standardized score MCID estimates range from 2.01 to 3.2 for distribution-based methods, and from 2.42 to 3.75 for sample-size-weighted anchor-based methods. Lower Vineland-II standardized score MCID estimates were observed for younger and more cognitively impaired populations. These MCID estimates enable users of Vineland-II to assess both the statistical and clinical significance of any observed change. Autism Res 2018, 11: 270-283. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: The Vineland Adaptive Behavior Scales (2nd edition; Vineland-II) is the most widely used scale for assessing day-to-day "adaptive" skills. Yet, it is unknown how much Vineland-II scores must change for those changes to be regarded as clinically significant. We pooled data from over 9,000 individuals with ASD to show that changes of 2-3.75 points on the Vineland-II Composite score represent the "minimal clinically-important difference." These estimates will help evaluate the benefits of potential new treatments for ASD.

Serotonergic basis of antipsychotic drug effects in schizophrenia.

Recent attention has been focused on the involvement of serotonin (5-HT) in the pathophysiology of schizophrenia and its role in mediating antipsychotic drug effects. There are two reasons for the new emphasis: the tremendous success of the so-called "atypical" antipsychotic drugs (a common feature of which is their high affinity for specific 5-HT receptor subtypes); and the elucidation of a complex family of 5-HT receptors whose function and pharmacology is only beginning to be understood. This paper will review the evidence that pertains to the role of 5-HT in mediating antipsychotic drug effects. The interaction of dopamine and 5-HT systems will be reviewed, and the mechanisms of action of atypical antipsychotic drugs will be evaluated in this context. The impact of serotonin on neurodevelopment, and the involvement of serotonin in the psychotomimetic and psychotogenic properties of hallucinogens, will be discussed. Together, these facts will be placed into the context of changes in serotonergic function in schizophrenia.

Double-blind, placebo-controlled study of amantadine hydrochloride in the treatment of children with autistic disorder.

OBJECTIVE: To test the hypothesis that amantadine hydrochloride is a safe and effective treatment for behavioral disturbances--for example, hyperactivity and irritability--in children with autism. METHOD: Thirty-nine subjects (intent to treat; 5-19 years old; IQ > 35) had autism diagnosed according to DSM-IV and ICD-10 criteria using the Autism Diagnostic Interview-Revised and the Autism Diagnostic Observation Schedule-Generic. The Aberrant Behavior Checklist-Community Version (ABC-CV) and Clinical Global Impressions (CGI) scale were used as outcome variables. After a 1-week, single-blind placebo run-in, patients received a single daily dose of amantadine (2.5 mg/kg per day) or placebo for the next week, and then bid dosing (5.0 mg/kg per day) for the subsequent 3 weeks. RESULTS: When assessed on the basis of parent-rated ABC-CV ratings of irritability and hyperactivity, the mean placebo response rate was 37% versus amantadine at 47% (not significant). However, in the amantadine-treated group there were statistically significant improvements in absolute changes in clinician-rated ABC-CVs for hyperactivity (amantadine -6.4 versus placebo -2.1; p = .046) and inappropriate speech (-1.9 versus 0.4; p = .008). CGI scale ratings were higher in the amantadine group: 53% improved versus 25% (p = .076). Amantadine was well tolerated. CONCLUSIONS: Parents did not report statistically significant behavioral change with amantadine. However, clinician-rated improvements in behavioral ratings following treatment with amantadine suggest that further studies with this or other drugs acting on the glutamatergic system are warranted. The design of these and similar drug trials in children with autistic disorder must take into account the possibility of a large placebo response.

Neural development, cell-cell signaling, and the "two-hit" hypothesis of schizophrenia.

To account for the complex genetics, the developmental biology, and the late adolescent/early adulthood onset of schizophrenia, the "two-hit" hypothesis has gained increasing attention. In this model, genetic or environmental factors disrupt early central nervous system (CNS) development. These early disruptions produce long-term vulnerability to a "second hit" that then leads to the onset of schizophrenia symptoms. The cell-cell signaling pathways involved in nonaxial induction, morphogenesis, and differentiation in the brain, as well as in the limbs and face, could be targets for a "first hit" during early development. These same pathways, redeployed for neuronal maintenance rather than morphogenesis, may be targets for a "second hit" in the adolescent or adult brain. Furthermore, dysregulation of cell-cell signaling by a "first hit" may prime the CNS for a pathologic response to a "second hit" via the same signaling pathway. Thus, parallel disruption of cell-cell signaling in both the developing and the mature CNS provides a plausible way of integrating genetic, developmental, and environmental factors that contribute to vulnerability and pathogenesis in schizophrenia.

5-HT1A receptors control neurite branching during development.

Serotonin (5-HT) is known to affect the motility and structure of responsive growth cones and to influence synaptic density in vitro. Whether these effects are produced via membrane bound serotonin receptors or another mechanism has been unknown. We demonstrate that high-affinity 5-HT receptors, present prenatally in rat brain, are asymmetrically distributed among cultured cortical neurons. Stimulation of the 5-HT1A receptors of these neurons in vitro specifically decreases the branching of neurites by 70% and reduces total neuritic length by more than half. These results are compatible with subtypes of serotonin receptors having important roles in mammalian neurodevelopment.

Are the neurodevelopmental effects of gonadal hormones related to sex differences in psychiatric illnesses?

There are large sex differences in the incidence of many psychiatric diseases. The bases for these sex differences are probably complex and are likely to involve the interaction of both social and biological factors. Probable social factors include child rearing practices, personal expectations and lifestyles, and societal institutions. Biological factors would likely include genetic effects, hormonally mediated neurodevelopmental effects and hormonally mediated neuroregulatory effects. This paper focuses upon the developmental effects of gonadal hormones. The sex differences observed in the neuroanatomy and behavior of nonhuman mammals are reviewed. The instances in which developmental exposure to gonadal hormones has been demonstrated to be involved in establishing these sexual dichotomies are surveyed. The molecular mechanisms by which differences in prenatal and early postnatal levels of gonadal hormones may generate such sex differences are examined. Sex differences in human neuroanatomy and cognitive function are discussed. Finally, we speculate on ways in which similar hormonal mechanisms might act to influence psychiatric disorders.

Effect of a uniform partial denervation of the periphery on the peripheral and central vibrissal system in guinea pigs.

In some rodents, somatotopically organized architectonic patterns corresponding precisely to the arrangement of the vibrissae on the face are found in each of the central stations of the trigeminal (V) pathway. Two lines of evidence indicate that these architectonic patterns reflect the level of peripheral innervation. First, in normal mice, the sizes of the individual units within the cortical representation are proportional to the number of fibers supplying the corresponding vibrissal follicles. Second, complete surgical denervation of groups of vibrissae can severely attenuate the sizes of and alter the patterns of their central representations. However, previous studies in this system do not distinguish the effects of the absolute and the relative levels of peripheral innervation on central representations. To address this question, we have studied guinea pigs in which all vibrissae are partially deafferentated before birth by fetal exposure to antibodies against NGF. This approach reduces the absolute level of peripheral innervation in a graded way, and does so uniformly, without changing the pattern of vibrissal innervation. In the most severely affected animals, only 18% of the normal number of V ganglion neurons survive. The effect of this loss on the V system was assessed by comparing the peripheral and central components of the vibrissal system in normal and NGF-deprived animals. Peripheral fibers from the V ganglion neurons, including those to the vibrissae, are less reduced in number (50%) than expected. The number of peripheral fiber fascicles is also decreased. In contrast, neither the patterns nor the areas of the central representations in medulla and cortex differ from those of normal animals. We conclude that 18% of the normal number of V ganglion cells is sufficient to establish normal central architectonic patterns and the size of the central vibrissal representations is independent of the absolute magnitude of peripheral innervation. These observations are of relevance to understanding the role of NGF on the morphogenesis of central somatosensory pathways, the effects of "mismatches" between peripheral innervation, and the development of projections to central targets in the mammalian brain, and provide new data for understanding competitive interactions in the developing central and peripheral trigeminal system.

A comprehensive analysis of 22q11 gene expression in the developing and adult brain.

Deletions at 22q11.2 are linked to DiGeorge or velocardiofacial syndrome (VCFS), whose hallmarks include heart, limb, and craniofacial anomalies, as well as learning disabilities and increased incidence of schizophrenia. To assess the potential contribution of 22q11 genes to cognitive and psychiatric phenotypes, we determined the CNS expression of 32 mouse orthologs of 22q11 genes, primarily in the 1.5-Mb minimal critical region consistently deleted in VCFS. None are uniquely expressed in the developing or adult mouse brain. Instead, 27 are localized in the embryonic forebrain as well as aortic arches, branchial arches, and limb buds. Each continues to be expressed at apparently constant levels in the fetal, postnatal, and adult brain, except for Tbx1, ProDH2, and T10, which increase in adolescence and decline in maturity. At least six 22q11 proteins are seen primarily in subsets of neurons, including some in forebrain regions thought to be altered in schizophrenia. Thus, 22q11 deletion may disrupt expression of multiple genes during development and maturation of neurons and circuits compromised by cognitive and psychiatric disorders associated with VCFS.