How Does Autism Affect Brain Responses to Rewards?

What you need to know

• People with autism showed reduced brain activity when anticipating both social and monetary rewards compared to those without autism.
• There were no major differences in brain responses when actually receiving rewards between those with and without autism.
• Having ADHD symptoms along with autism appeared to partially counteract the reduced reward anticipation responses.

How the brain processes rewards

Our brains have a built-in reward system that helps motivate us to seek out positive experiences. This system involves several brain regions, including an area called the ventral striatum. The ventral striatum becomes active both when we anticipate a potential reward (the “wanting” phase) and when we actually receive a reward (the “liking” phase).

Researchers have been interested in studying how this reward system may work differently in people with autism spectrum disorder (ASD). Some theories have suggested that social interactions may not be as inherently rewarding for people with autism, which could contribute to social difficulties. However, past studies on reward processing in autism have had mixed results.

A large study of reward responses in autism

To get a clearer picture, researchers conducted a large brain imaging study with over 200 people with autism and 180 people without autism. Participants completed two tasks while their brains were scanned:

1. A social reward task, where they could earn smiles from a face on the screen
2. A monetary reward task, where they could earn small amounts of money

The researchers looked at brain activity in the ventral striatum during both the anticipation phase (when participants saw a cue indicating a potential reward) and the delivery phase (when participants received the reward).

Reduced reward anticipation in autism

The key finding was that people with autism showed less ventral striatum activation when anticipating both social and monetary rewards compared to those without autism. This suggests a general reduction in reward anticipation or “wanting” responses, rather than a specific issue with social rewards.

Interestingly, there were no major differences between groups in brain responses when actually receiving the rewards. This indicates that the “liking” phase of reward processing may be relatively intact in autism.

The impact of ADHD symptoms

Many people with autism also have symptoms of attention-deficit/hyperactivity disorder (ADHD). The researchers found that participants with both autism and significant ADHD symptoms showed less of a reduction in reward anticipation responses compared to those with just autism. In other words, having ADHD symptoms seemed to partially counteract the effect seen in autism alone.

What do these findings mean?

These results suggest that people with autism may have a generalized reduction in reward anticipation, rather than a specific deficit related to social rewards. This could potentially affect motivation and learning across different types of situations.

The finding that actual reward responses were similar between groups is somewhat reassuring. It suggests that people with autism can still experience pleasure from rewards, even if they may not anticipate them as strongly.

The interaction with ADHD symptoms highlights the importance of considering co-occurring conditions when studying autism. It also raises interesting questions about how these two conditions might interact at a brain level.

Limitations and future directions

It’s important to note that this study looked at average responses across groups. There is likely to be a lot of individual variation in reward processing among people with autism. The study also used fairly simple reward tasks in a laboratory setting, which may not fully capture real-world reward experiences.

Future research could explore:

• How reward processing in autism might change across development
• Whether there are subgroups of people with autism who show different patterns of reward responses
• How reward processing relates to specific autism traits or behaviors
• Developing interventions to potentially enhance reward anticipation in autism

Conclusions

• People with autism showed reduced brain activity when anticipating rewards, but similar responses when receiving rewards, compared to those without autism.
• This pattern was seen for both social and monetary rewards, suggesting a general effect rather than a specific social deficit.
• Having ADHD symptoms along with autism seemed to partially offset the reduced anticipation effect.
• These findings enhance our understanding of motivation and reward processing in autism, which could inform future interventions and support strategies.