How Does Family History of Substance Use Disorder Affect Reward Processing in Teens With and Without ADHD?

What you need to know

• This study looked at how family history of substance use disorder (SUD) affects brain activity related to rewards in teens with and without ADHD.

• Teens with a family history of SUD showed different patterns of brain activity in areas involved in attention and decision-making when processing rewards.

• The findings suggest that family history of SUD may impact how the brain processes rewards differently in those with and without ADHD, which could relate to SUD risk.

Background on ADHD and Substance Use Disorder Risk

Attention-deficit/hyperactivity disorder (ADHD) is a common condition that affects many children and adults. People with ADHD often have difficulties with attention, hyperactivity, and impulsivity. Research has shown that individuals with ADHD are at higher risk of developing substance use disorders (SUDs) compared to those without ADHD. In fact, people with ADHD are 2-3 times more likely to develop problems with alcohol, drugs, or nicotine use.

There are likely multiple factors that contribute to this increased SUD risk in ADHD. One important factor may be differences in how the brain processes rewards. Both ADHD and SUDs have been associated with alterations in the brain’s reward system. However, it’s not clear if these reward processing differences are present before substance use begins, or if they only emerge after someone starts using substances.

To try to tease this apart, researchers can look at adolescents who have a family history of SUD but have not used substances themselves yet. A family history of SUD is a known risk factor for developing substance use problems. By studying teens with a family history of SUD who have not used substances, we can get insight into potential “pre-existing” differences in reward processing that may increase risk.

What Did This Study Examine?

This study aimed to investigate how family history of SUD affects reward processing in the brain in adolescents with and without ADHD symptoms. Importantly, the researchers only included teens who did not have any substance use problems themselves. This allowed them to look at potential pre-existing brain differences, rather than changes caused by substance use.

The study included four groups of participants:

1. Teens with ADHD and a family history of SUD
2. Teens with ADHD and no family history of SUD
3. Teens without ADHD and with a family history of SUD
4. Teens without ADHD and no family history of SUD

All of the participants completed a task while their brains were scanned using functional magnetic resonance imaging (fMRI). The task involved anticipating and receiving monetary rewards. This allowed the researchers to examine brain activity related to reward processing.

Key Findings on Reward Processing

The study found several interesting differences in brain activity during reward processing between the groups:

Effects of ADHD Symptoms

Teens with more ADHD symptoms showed increased activity in a brain region called the dorsolateral prefrontal cortex when anticipating rewards. This area is involved in attention, working memory, and cognitive control.

The researchers suggest this may reflect that individuals with ADHD symptoms need to engage more cognitive resources to process reward information. In other words, their brains may have to “work harder” during reward anticipation.

Effects of Family History

Having a family history of SUD was associated with altered activity in the ventrolateral prefrontal cortex during reward receipt. However, this effect depended on ADHD symptom levels.

Specifically, in teens with a family history of SUD, those with higher ADHD symptoms showed increased activity in this region when receiving rewards. The ventrolateral prefrontal cortex is involved in decision-making, inhibition, and attention.

This suggests that family history of SUD may impact how the brain processes rewards differently in those with and without ADHD symptoms.

No Differences in Key Reward Region

Interestingly, the study did not find any differences between groups in activity of the ventral striatum - a core region of the brain’s reward system. This was somewhat surprising, as previous studies have found alterations in this region in both ADHD and SUD.

The researchers suggest this could mean that differences in ventral striatum activity emerge later in development, or only after substance use begins. Alternatively, the specific task used may not have been optimal for detecting differences in this region.

Additional Findings

In a follow-up analysis, the researchers used a stricter definition of family history of SUD, focusing specifically on alcohol use disorder. With this definition, they found that teens with a family history showed increased activity in the anterior cingulate cortex during reward anticipation. This brain region is involved in reward processing, decision-making, and emotion regulation.

This highlights how different ways of defining family history may lead to somewhat different results. It suggests that a family history of alcohol problems specifically may have distinct effects on the brain compared to a broader family history of substance use issues.

What Do These Findings Mean?

Overall, this study provides evidence that both ADHD symptoms and family history of SUD are associated with differences in how the brain processes rewards, even in teens who have not used substances themselves.

The findings suggest that ADHD and family history of SUD may impact somewhat different brain circuits involved in reward processing. ADHD symptoms were associated with altered activity in regions involved in attention and cognitive control. Meanwhile, family history effects were seen more in areas related to decision-making and inhibition.

Importantly, some of the family history effects depended on ADHD symptom levels. This indicates that teens with both ADHD symptoms and a family history of SUD may have distinct patterns of brain activity during reward processing.

These reward processing differences could potentially contribute to increased risk for developing substance use problems. For example, altered activity in regions involved in decision-making and inhibition could relate to more impulsive choices around substance use.

However, it’s important to note that this study cannot prove these brain differences directly cause increased SUD risk. More research is needed to determine if and how these reward processing alterations may contribute to substance use vulnerability.

Conclusions

• Both ADHD symptoms and family history of SUD are associated with differences in brain activity during reward processing in teens.

• These effects involve somewhat different brain regions, with ADHD impacting attention/cognitive control areas and family history affecting decision-making/inhibition regions.

• Some family history effects depend on ADHD symptom levels, suggesting distinct patterns in those with both risk factors.

• More research is needed to determine how these brain differences may relate to future substance use risk and to develop targeted prevention strategies.

This study provides new insights into how ADHD and family history of SUD may impact the brain’s reward system before substance use begins. Understanding these pre-existing differences could help identify teens at highest risk and inform the development of more personalized prevention and treatment approaches. Future studies should continue to investigate how these brain differences may change with development and substance use initiation.