Mirtazapine for the treatment of public masturbation and inappropriate sexual behaviors in autism

By Nestor Lopez-Duran PhD

The issue of public masturbation in kids with autism is probably one of the most uncomfortable topics for parents to discuss with their clinicians or pediatricians. I usually can sense when a parent wants to bring up the topic, and the parents are usually relieved when I address the issue directly. Inappropriate sexual behaviors (public masturbation or nudity, sexually touching of strangers, etc) are actually not that uncommon among children with a variety of developmental disorders, including autism.
Usually clinicians recommend behavioral modification techniques, similar to the techniques used to decrease the rates of any other undesirable behaviors (please note that in this post I am not talking about masturbation as an undesirable behavior. I am instead talking about public masturbation or other type of public sexual behaviors that are considered in most societies to be inappropriate). But often, when the behaviors are not responsive to behavioral interventions, many children show improvements from the use of specific medications.

A review of: Coskun, M., Karakoc, S., Kircelli, F., & Mukaddes, N. (2009). Effectiveness of Mirtazapine in the Treatment of Inappropriate Sexual Behaviors in Individuals with Autistic Disorder Journal of Child and Adolescent Psychopharmacology, 19 (2), 203-206 DOI: 10.1089/cap.2008.020

In a study published in the journal of Child and Adolescent Psychopharmacology, a team of researchers from Turkey examined the effectiveness and safety of Mirtazapine (Rameron) for the treatment of inappropriate sexual behaviors in autism. The study included 10 children with a diagnosis of autism (8 boys and 2 girls, ranging in age from 5 to 16). These children had received behavioral and psychoedcucational interventions for their inappropriate sexual behaviors but these interventions did not reduce these problems. The authors described the percentage of the children who engaged in the different concerning behaviors: non-private masturbation (100%), touching people inappropriately (50%), disrobing in public (20%), sexual interest in particular body parts or nonhuman objects (20%), and observing people bathing or undressing (10%). Two of these children had a co-morbid diagnosis of ADHD and two others had a co-morbid diagnosis of depression.

The children were treated with an initial dosage of 7.5-15mg per day and this was increased according to response and side effects to a maximum of 30mg per day.

The results:
Based on the excessive masturbation item from the Clinical Global Impressions-Improvement Scale, the authors found that:

50% of the subjects showed very much improvement
30% showed much improvement
10% showed moderate improvement

The researchers then concluded that the study provides support for the effectiveness of Mirtazapine in the treatment of inappropriate sexual behaviors in children with autism.

But why Mirtazapine?

Mirtazapine is relatively old anti-depressant that is still commonly used. In clinical practice Mirtazapine is often used used because (instead of despite of) some of its side effects (in specific cases desirable side effects). For example, Mirtazapine is associated with significant weight gain, thus it is commonly used for the treatment of depression in people with anorexia. Likewise, Mirtazapine is associated with severe drowsiness, thus it is often used for individuals with depression and insomnia. Thus, the selection of Mirtazapine for this study was also related to another side effect. While SSRI antidepressants (such as Prozac) are associated with sexual dysfunction (for example erectile dysfunction), Mirtazapine has been found to reduce libido (reduced sexual desire). Thus, it is sensible to expect that this medication, by reducing libido, would be effective in the treatment of inappropriate sexual behaviors.

However, the authors correctly discussed the most obvious limitation of this study: no control condition. Since there was no control group taking a placebo pill, it is impossible to tell for sure whether the improvements observed were due to the medication or to the placebo effect (e.g., the expectation by the parents that the medication was supposed to work). Thus, although the study provides some preliminary evidence of the potential effectiveness of Mirtazapine for the treatment for excessive non-private masturbation, there is a need for placebo-controlled studies using larger sample sizes.