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Autism: Does Reward System Dysfunction Lead to a Lack of Social Engagement?

Individuals affected by autism often prioritize interest stimuli over social stimuli, depriving them of crucial opportunities for social learning.  New research investigates how the reward system in the brain of those with autism responds to motivational stimuli.

Autism is a pervasive developmental condition characterized by difficulty with speech and nonverbal communication, sociability, and restricted and repetitive behaviours and interests (RRBIs). Since the symptoms, severity, presentation, and prognosis are so variable, autism is referred to using the umbrella term autism spectrum disorder (ASD). It is estimated that autism affects as many as one out of every 68 people.

The developmental symptoms of autism typically become apparent in affected children between the ages of 18 months and three years of age. However, there is also an array of other disorders or conditions which tend to present together with autism.  These include ADHD, eating disorders, intellectual disability, sensory processing disorder, and oppositional defiance disorder.

What Causes Autism?

While the causes of ASD are not well understood, scientists generally agree that, rather than having a single cause, it is probably due to a combination of genetic and environmental factors. Some of the environmental risk factors for ASD include:

  • Maternal gestational diabetes
  • Maternal infection during the first trimester
  • Maternal exposure to certain medications (such as Valproate) or pesticides during the first trimester
  • Low maternal levels of folic acid

How is Autism Treated?

To date, treatment options have been limited. Behavioural interventions, such as Applied Behavioural Analysis (ABA therapy) are most common because they focus on using learning principles and motivational strategies (rewards) to teach socially significant behaviours in real-life contexts.  For example, ABA therapy is often used to teach individuals on the spectrum adaptive living skills such as personal self-care, domestic skills, time and punctuality, and social skills.

Reward System

In a recent study published in Molecular Autism, a team of American and German researchers investigated how the reward system in the brain responds to both interest rewards and social rewards and if the brain’s responses differed when intellectual disability was also present.

The research team recruited 61 youth (ages 8-17; 39 with ASD and 22 with ASD with intellectual disability) to participate in their study.  Each participant was briefly interviewed to evaluate their favourite interests and hobbies (such as sports, video games, musicians, toys, and movies) so that individualized video clips of social and interest rewards could be created.  Additionally, all parents were asked to complete the Social Responsiveness Scale-2nd Edition, the Repetitive Behavior Scale-Revised, and the Interests Scale to assess behaviors that are characteristic of ASD.  Each participant had three functional MRIs to illuminate their motivation to receive a reward based on their individual interests or one that was neutral.

Their findings were consistent with past research that has shown that people with ASD are hyper-reactive to non-social circumscribed interests and hypo-reactive to social rewards (such as approval).  The researchers speculate that reward system dysfunction, most pronounced within the caudate nucleus, may contribute to an enhanced motivation for restricted and repetitive behaviours and interests in ASD, accompanied by diminished motivation for social engagement.  As a result, using these interests as a reward may be an effective strategy to support behaviour modification programs such as ABA therapy.

Written by Debra A. Kellen, PhD


(1) Kohls, G., Antezana, L., Mosner, M. G., Schultz, R. T., & Yerys, B. E. (2018). Altered reward system reactivity for personalized circumscribed interests in autism. Molecular Autism9(1), 9. DOI 10.1186/s13229-018-0195-7



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