A randomized double-blind, placebo-controlled pilot trial of mirtazapine for anxiety in children and adolescents with autism spectrum disorder

This study was a 10-week double-blind, placebo-controlled pilot trial of mirtazapine for anxiety in youth with autism spectrum disorder (ASD). Participants were ages 5 to 17 years with ASD and clinically significant anxiety (Pediatric Anxiety Rating Scale [PARS] score ≥10). Thirty participants were randomized to mirtazapine (7.5-45 mg/day) or placebo in a 2:1 ratio. The co-primary outcome measures were the PARS and the Clinical Global Impressions-Improvement subscale (CGI-I). Mirtazapine resulted in a statistically significant within group decrease in anxiety on the PARS (ES 1.76, p < 0.001). The improvement in PARS score for mirtazapine versus placebo was clinically meaningful but not statistically significant (ES = 0.63, p = 0.64). Forty-seven percent of participants assigned to mirtazapine (95% CI 22%: 74%) and 20% assigned to placebo (95% CI 2%: 60%) were rated "much improved" (CGI-I = 2) or "very much improved" (CGI-I = 1) for anxiety, p = 0.46. No statistically significant differences in mean 10-week changes between mirtazapine and placebo occurred on any outcome measure. There were no statistically significant differences in adverse effect frequency between mirtazapine and placebo. The results are consistent with mirtazapine's safety and tolerability and meet three of four pre-specified indicators of efficacy (statistically significant change in total PARS score for mirtazapine, numerically greater reduction in total PARS score for mirtazapine than placebo, numerically higher number of responders to mirtazapine than placebo, but not greater than 50% of participants receiving mirtazapine rated as responders). Implementation of a larger randomized controlled trial of mirtazapine for the treatment of anxiety in this population is supported.Clinical trial registration information: Mirtazapine Treatment of Anxiety in Children and Adolescents with Pervasive Developmental Disorders; https://clinicaltrials.gov ; NCT01302964.

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.

Psychopharmacological interventions in autism spectrum disorder

INTRODUCTION

Individuals with autism spectrum disorder (ASD) commonly present for treatment of emotional and behavioral disturbances associated with ASD's "core" symptoms. Psychotropic medications are widely utilized in alleviating associated emotional and behavioral symptoms.

AREAS COVERED

Emotional and behavioral disturbances associated with ASD include irritability/severely disruptive behavior, which comprises the heaviest symptom burden; hyperactivity and other Attention-Deficit-Hyperactivity-Disorder (ADHD)-type symptoms; repetitive/stereotyped behaviors; and social withdrawal. Existing evidence for medications for each of these symptom clusters will be examined in this review.

EXPERT OPINION

Psychopharmacological treatment of core and associated symptoms in ASD is challenging, in large part because of the heterogeneity in the presentation of ASD. Furthermore, children and adolescents with ASD are more vulnerable to the side effects of psychopharmacological intervention than their age-matched, typically developing counterparts. Currently, risperidone and aripiprazole are the only medications that have been (relatively) reliably shown to help treat certain symptom clusters associated with ASD, namely severely disruptive behavior and hyperactivity. Recent studies have begun to look at medications with mechanisms that are novel in the treatment of ASD and that may address underlying pathophysiology and/or core symptoms such as glutamate-modulating agents. Overall, randomized, placebo-controlled studies of medications for the treatment of ASD are scarce.