Letter to the Editor: Treating Autism-Associated Sexual Compulsions with Naltrexone

To the Editor:

Naltrexone has found utility in treating compulsions, including paraphilic disorders in the literature; however, little data exist about the use of naltrexone in patients with autism spectrum disorder (ASD). The data present offer little insight into compulsive sexual behaviors (CSBs) associated with ASD and often addresses other behavioral disturbances (Brown et al. 2009).

A is a 17-year-old boy with ASD and mild intellectual disability (IQ of 68) who was transferred to us from a clinician after failed treatment for increasing aggression and CSBs for 2 years. A's ego syntonic sexual thoughts and masturbation began at age 12, and progressively got more frequent, manifesting in inappropriate settings. With age, associated pervasive behaviors took root, including credit card theft and purchasing thousands of dollars' worth of pornography online. He began frequently breaking into rooms of relatives and friends to steal items that he could utilize as sexual paraphernalia. When confronted, he often escalated with aggression, destroying property and screaming, with poor redirectability. With age, he grew irritable at baseline, frequently misbehaving in school, and with poor academic performance. Multiple medications were tried in the preceding year, including valproic acid 500 mg twice daily, risperidone 0.5 mg twice daily, and fluoxetine 40 mg and clonazepam 0.5 mg twice daily as needed. Upon transfer, valproic acid, fluoxetine, and clonazepam were stopped and paroxetine was started to decrease sexual urges, with no benefit noted.

As his aggression escalated, we initiated olanzapine, which was started at 5 mg increased to 10 mg nightly after 2 weeks. This mitigated his physical outbursts but did not reduce CSBs. Ultimately naltrexone 50 mg was started with a reported 90% reduction of CSBs in 2 weeks. The medication was well tolerated with no side effects or changes in liver function testing. Maintained on the naltrexone the behavior diminished until near absence 1 year later.

Although not well studied, some literature suggests that naltrexone can decrease symptoms of ASD, including self-harm behaviors. Likewise, it has been used in populations to control inappropriate sexual behaviors. An opioid antagonist, mu and delta receptor blockade may mitigate the reinforcement of CSBs and the sexual release of masturbation. In addition, an increase in endogenous opioid production may be contributory to the cessation of said behaviors (Roy et al. 2015). Data on the pharmacological treatment of CSBs associated with ASD are limited, the extent of which are case reports supporting the use of mirtazapine (Coskun et al. 2008). Accumulating reports suggest that naltrexone is safe in children and adolescents and could represent a viable long-term treatment option (Elchaar et al. 2006).