Does Pregnenolone Adjunct to Risperidone Ameliorate Irritable Behavior in Adolescents With Autism Spectrum Disorder: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial?

Neuroactive Steroids, Toll-like Receptors, and Neuroimmune Regulation: Insights into Their Impact on Neuropsychiatric Disorders

Pregnane neuroactive steroids, notably allopregnanolone and pregnenolone, exhibit efficacy in mitigating inflammatory signals triggered by toll-like receptor (TLR) activation, thus attenuating the production of inflammatory factors. Clinical studies highlight their therapeutic potential, particularly in conditions like postpartum depression (PPD), where the FDA-approved compound brexanolone, an intravenous formulation of allopregnanolone, effectively suppresses TLR-mediated inflammatory pathways, predicting symptom improvement. Additionally, pregnane neurosteroids exhibit trophic and anti-inflammatory properties, stimulating the production of vital trophic proteins and anti-inflammatory factors. Androstane neuroactive steroids, including estrogens and androgens, along with dehydroepiandrosterone (DHEA), display diverse effects on TLR expression and activation. Notably, androstenediol (ADIOL), an androstane neurosteroid, emerges as a potent anti-inflammatory agent, promising for therapeutic interventions. The dysregulation of immune responses via TLR signaling alongside reduced levels of endogenous neurosteroids significantly contributes to symptom severity across various neuropsychiatric disorders. Neuroactive steroids, such as allopregnanolone, demonstrate efficacy in alleviating symptoms of various neuropsychiatric disorders and modulating neuroimmune responses, offering potential intervention avenues. This review emphasizes the significant therapeutic potential of neuroactive steroids in modulating TLR signaling pathways, particularly in addressing inflammatory processes associated with neuropsychiatric disorders. It advances our understanding of the complex interplay between neuroactive steroids and immune responses, paving the way for personalized treatment strategies tailored to individual needs and providing insights for future research aimed at unraveling the intricacies of neuropsychiatric disorders.

Emerging drugs for the treatment of irritability associated with autism spectrum disorder

INTRODUCTION

Autism spectrum disorder (ASD) is an early-onset disorder with a prevalence of 1% among children and reported disability-adjusted life years of 4.31 million. Irritability is a challenging behavior associated with ASD, for which medication development has lagged. More specifically, pharmacotherapy effectiveness may be limited against high adverse effects (considering side effect profiles and patient medication sensitivity); thus, the possible benefits of pharmacological interventions must be balanced against potential adverse events in each patient.

AREAS COVERED

After reviewing the neuropathophysiology of ASD-associated irritability, the benefits and tolerability of emerging medications in its treatment based on randomized controlled trials were detailed in light of mechanisms and targets of action.

EXPERT OPINION

Succeeding risperidone and aripiprazole, monotherapy with memantine may be beneficial. In addition, N-acetylcysteine, galantamine, sulforaphane, celecoxib, palmitoylethanolamide, pentoxifylline, simvastatin, minocycline, amantadine, pregnenolone, prednisolone, riluzole, propentofylline, pioglitazone, and topiramate, all adjunct to risperidone, and clonidine and methylphenidate outperformed placebo. These effects were through glutamatergic, γ-aminobutyric acidergic, inflammatory, oxidative, cholinergic, dopaminergic, and serotonergic systems. All medications were reported to be safe and tolerable. Considering sample size, follow-up, and effect size, further studies are necessary. Along with drug development, repositioning and combining existing drugs supported by the mechanism of action is recommended.

Cilostazol as adjunctive therapy in treatment of children with autism spectrum disorders: a double-blind and placebo-controlled randomized trial

We aimed to evaluate cilostazol therapeutic effects on aberrant behaviors of autism spectrum disorder (ASD) children and its safety profile in a double-blind, randomized clinical trial. Sixty-six children with confirmed ASD were allocated to receive either daily 50-mg cilostazol (increased to 100 mg/day after 2 weeks) or matched placebo in addition to risperidone. The Aberrant Behavior Checklist-Community Edition (ABC-C) scale and a checklist of probable adverse effects were used to assess the behavioral outcomes and safety profile at weeks 0, 5, and 10 of the study. Sixty-one participants, with comparable baseline characteristics, completed the trial. Unlike other ABC-C subscales, repeated-measures analysis showed significant effect for time × treatment interaction in the hyperactivity subscale ( P = 0.047; partial eta squared = 0.06). We used the median value for the baseline score hyperactivity subscale [median (interquartile range) = 31 (24-37)] to stratify participants to higher hyperactivity and lower hyperactivity subgroups and found that only participants with higher hyperactivity benefit from cilostazol adjunctive therapy ( P = 0.028; partial eta squared = 0.14). Cilostazol could be considered as a safe agent with beneficial effects on hyperactivity in children with ASD and higher levels of hyperactivity.

Systematic Review and Meta-analysis: Pharmacological and Nonpharmacological Interventions for Persistent Nonepisodic Irritability

OBJECTIVE

This meta-analysis examined the efficacy of available pharmacological and nonpharmacological interventions for irritability among youth with autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), disruptive behavior disorders (DBD), disruptive mood dysregulation disorder (DMDD), and/or severe mood dysregulation (SMD).

METHOD

Literature searches were conducted in October 2020, resulting in 564 abstracts being reviewed to identify relevant papers, with 387 articles being reviewed in full. A random effects model was used for the meta-analysis, with subgroup meta-regressions run to assess effects of study design, intervention type, medication class, and clinical population.

RESULTS

A total of 101 studies were included (80 pharmacological, 13 nonpharmacological, 8 combined). Despite high heterogeneity in effects (I2 = 94.3%), pooled posttreatment effect size for decreasing irritability was large (Hedges' g = 1.62). Large effects were found for pharmacological (g = 1.85) and nonpharmacological (g = 1.11) interventions; moderate effects were found for combined interventions relative to monotherapy interventions (g = 0.69). Antipsychotic medications provided the largest effect for reducing irritability relative to all other medication classes and nonpharmacological interventions. A large effect was found for youth with ASD (g = 1.89), whereas a medium effect was found for youth with ADHD/DMDD/DBD/SMD (g = 0.64).

CONCLUSION

This meta-analysis provides a comprehensive review of interventions targeting persistent nonepisodic irritability among youth with various psychiatric disorders. Strong evidence was found for medium-to-large effects across study design, intervention type, and clinical populations, with the largest effects for pharmacological interventions, particularly antipsychotic medications and combined pharmacological interventions, and interventions for youth with ASD.

Overlapping Molecular Pathways Leading to Autism Spectrum Disorders, Fragile X Syndrome, and Targeted Treatments

Autism spectrum disorders (ASD) are subdivided into idiopathic (unknown) etiology and secondary, based on known etiology. There are hundreds of causes of ASD and most of them are genetic in origin or related to the interplay of genetic etiology and environmental toxicology. Approximately 30 to 50% of the etiologies can be identified when using a combination of available genetic testing. Many of these gene mutations are either core components of the Wnt signaling pathway or their modulators. The full mutation of the fragile X mental retardation 1 (FMR1) gene leads to fragile X syndrome (FXS), the most common cause of monogenic origin of ASD, accounting for ~ 2% of the cases. There is an overlap of molecular mechanisms in those with idiopathic ASD and those with FXS, an interaction between various signaling pathways is suggested during the development of the autistic brain. This review summarizes the cross talk between neurobiological pathways found in ASD and FXS. These signaling pathways are currently under evaluation to target specific treatments in search of the reversal of the molecular abnormalities found in both idiopathic ASD and FXS.