Low-Dose Risperidone for an Autistic Child with Comorbid ARFID and Misophonia

Abstract

Avoidant/Restrictive Food Intake Disorder and misophonia seem to be overrepresented in autism spectrum disorder. Literature is mute on psychopharmacotherapy in these complex presentations. Here, authors report on a challenging case of low-functioning ASD child with comorbid ARFID and misophonia that responded favorably to a low-dose risperidone. This is followed by a brief discussion of purported pharmacodynamic mechanisms and relevant literature.

Case Report

As part of consultation-liaison paediatric psychiatric service, we were called upon to see a 4-year-old Egyptian boy, a known case of low-functioning, essential, non-verbal, hyperkinetic, non-epileptic ASD that has been recently repeatedly admitted to IP facility in severe dehydration and marasmus. Hospitalizations are typically preceded by total refusal of oral intake for few days with no apparent reason. Apart from dyselectrolemia, nothing abnormal is detected on exhaustive lab workup and imaging. Parentral drips are always mandated for prompt hydration. Interestingly, staff noticed that the child is readily startled, agitated and covering both ears at sound of unfolding ‘velcro’ armcuffs when taking BP measurements routinely. A working diagnosis of comorbid ARFID/misophonia was entertained by our team. Given moribund and frailty of case, neurodisability and difficult assessment, and in light of repeated admissions, parents’ consent was obtained to embark on a trial of low-dose risperidone (0.25 mL bid). Over a week, there was a tangible response-increased PO food intake and markedly diminished misophonia. Sixteen weeks after discharge, the child put on 3.5 Kg, is reported to be far less disruptive, enrolled in intensive behavioural program, and above all with no more misophonia or hospital admissions.

Atypical Antipsychotics in ASD

Pharmacotherapy in ASD is indicated if psycho-social and educational interventions fail. Atypical antipsychotics have the strongest evidence-base so far, with both risperidone and aripiprazole are FDA-approved for severe irritability. Risperidone, based on at least 8 RCTs, can help with challenging behaviours in ASD and is FDA approved for 5 years of age.¹

Risperidone was suggested in this case on a two-fold premise-first, to stimulate appetite and weight gain. Mechanistically, AAPs induce weight gain by H1 blockade and 5HT2C antagonism actions on pro-opio-melanocortin (POMC) neurones. Pancreatic M3 blockade might be contributory.² Second, by virtue of a dopalytic action (D2 blockade) subserving as a ‘mental lubricant’, risperidone might challenge autistic frontal cognitive inflexibility that could underlie ARFID in this case.³ We failed to locate any report on risperidone treatment of ARFID (cf. olanzapine).

For misophonia, it is possible that risperidone improves deficits of sensory gating in retarded children with autism.⁴ Cortical hyperexcitation and frontal deficit in reducing sensory gating is reported in autism. There is a report that atypical antipsychotics, including risperidone improves sensory gating deficits in schizophrenia. Risperidone modulates auditory information processing in patients with schizophrenia. This could explain the remarkable response in our report. Adanir⁵ et al. reported a paradoxical increase in hypercusis associated with risperidone in an autistic child, though.

At times, it sounds difficult on clinical grounds to tease out misophonia, phonophobia, and hypercusis.

ARFID

Avoidant/restrictive food intake disorder or ARFID as shorthand has been widely accepted as a valid diagnostic construct since its inclusion in DSM-5 based on consistent evidence supporting differences in clinical presentation with other eating disorders. Sorely, comprehensive epidemiologic data in fully representative populations remain very limited, though preliminary data speaks to male and younger preponderance. DSM-5 diagnostic criteria currently include 3 patterns that we feel it could correspond to 3 clinical subtypes-anhedonic/restrictive, avoidant/picky eater, aversive/phobic. Alternatively, some authors contrasted 2 varieties-one restrictive with body image concerns and one without. Postulated explanatory models have been posited. A 3-dimensional model gained some popularity hypothesizing neurobiological abnormalities in sensory perception, homeostatic appetite, and negative valence systems. Pica, ARFID, and Rumination Disorder Interview (PARDI) was developed to aid in clinical assessment. It provides detailed clinical information as well as diagnostic algorithms and is available in multi-informant formats. Multi-modal, multi-disciplinary input is generally required. Several different medications have been reported as possible adjunctive treatment approaches for ARFID, with positive outcomes noted in some patients taking olanzapine, fluoxetine, cyproheptadine, and mirtazapine.⁶ Some have observed a small number of ARFID patients might go on to be classified anorexia nervosa (AN) as treatment progresses but outcomes considerably vary which is consistent with heterogeneity of disorder.

Both AN and ARFID have high prevalence rates of ASD (16 and 12.5% respectively) as demonstrated in a recent prospective multicentre cohort study.⁷

Misophonia

Misophonia is a form of decreased sound tolerance-a hypersensitivity to selective types of sounds; commonly sounds of someone chewing, repeated tapping, sniffing … These tend to instigate considerable emotional and physical arousal and distress as well, in those with misophonia, who would often engage in avoidance behaviours as an attempt to escape from the upsetting auditory stimuli. Misophonia is thought to be associated with enhanced connections between auditory, limbic and autonomic nervous system. Misophonia is still an unclassified disorder and we urge to consider it within updated editions of current classificatory systems (DSM-5 and ICD-11). The most researched and reported comorbidity for misophonia has been OCD and related conditions (e.g. Tourette syndrome). Treatment literature on misophonia include tinnitus retraining therapy, CBT (exposure and response prevention), and components of DBT and ACT as adjuncts. Psychopharmacotherapy is limited to handful case reports including BDZs (alprazolam), SSRIs (sertraline), and risperidone akin to our report here.^8–9

In a recent study, Dutch investigators found out comorbid DSM-IV axis I diagnoses in 28% of those with misophonia; 3% had ASD.¹⁰

Conclusions

Several significant challenges remain in terms of characterization and management of both ARFID and misophonia. These are even compounded in special populations as CAP and ASD where diagnostic ambiguities abound. Reports, including ours, though remain speculative, might inform some insights into approaching such complicated scenarios on clinical grounds.