How Are ADHD and Autism Symptoms Connected in Children?

What you need to know

• ADHD and autism symptoms tend to cluster separately in children from the general population, with stronger connections between symptoms of the same disorder.
• Some ADHD symptoms that occur in social contexts, like interrupting others, show moderate connections to autism symptoms.
• The overlap between certain ADHD and autism symptoms may reflect shared underlying causes or similarities in how the symptoms are described.

Understanding the overlap between ADHD and autism symptoms

Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder are two common neurodevelopmental conditions that often co-occur in children and adolescents. ADHD is characterized by persistent inattention and/or hyperactivity-impulsivity, while autism involves challenges with social communication and restricted, repetitive behaviors or interests.

While we know these conditions frequently overlap, less is known about exactly how individual symptoms of ADHD and autism relate to each other. A new study published in the Journal of Child Psychology and Psychiatry used an innovative statistical approach called network analysis to examine the connections between ADHD and autism symptoms in over 7,000 children from the general population in Brazil.

What is network analysis?

Network analysis is a method that allows researchers to visualize and quantify the relationships between individual symptoms, rather than looking at averaged scores or broad categories. In a symptom network, each symptom is represented by a “node” and the connections between symptoms are represented by “edges.” Stronger connections indicate symptoms that are more likely to occur together.

This approach can provide unique insights into how symptoms cluster and influence each other. It moves beyond traditional methods that group symptoms into categories and instead examines the complex web of relationships between individual behaviors and experiences.

How ADHD and autism symptoms cluster

The researchers found that overall, ADHD and autism symptoms tended to cluster separately, with stronger connections between symptoms of the same disorder. Only about 10% of the possible connections between ADHD and autism symptoms were present in the network.

This suggests that in the general child population, ADHD and autism traits align fairly closely with traditional diagnostic boundaries. Children who show some ADHD symptoms are more likely to have other ADHD symptoms, rather than autism symptoms, and vice versa.

However, there were some interesting connections observed between certain ADHD and autism symptoms. ADHD symptoms that tend to manifest in social situations showed the strongest links to autism symptoms. These included behaviors like:

• Talking excessively
• Blurting out answers
• Not waiting for one’s turn
• Interrupting or intruding on others

Bridging symptoms between ADHD and autism

The researchers identified certain “bridge symptoms” that showed the strongest connections between the ADHD and autism domains. For ADHD, these included symptoms like fidgeting, avoiding tasks requiring sustained attention, not waiting one’s turn, and intruding on others.

For autism, symptoms with the strongest bridges to ADHD included difficulties taking turns in conversations, fixating conversations on favorite topics, not understanding polite behavior, and trouble joining in play with other children.

Interestingly, some of the ADHD symptoms with the strongest connections to autism were considered potentially redundant with autism symptoms. For example, “intruding on others” (an ADHD symptom) and “being bad at taking turns in conversations” (an autism symptom) may be capturing very similar behaviors.

What does this mean?

These findings provide a more nuanced picture of how ADHD and autism symptoms relate to each other in children from the general population. While the symptoms largely cluster separately, there are some important areas of overlap, particularly for ADHD symptoms that manifest socially.

The redundancy between certain ADHD and autism symptoms raises some interesting questions. Do these overlapping symptoms reflect shared underlying causes for social difficulties across neurodevelopmental conditions? Or are the questionnaires used to assess ADHD and autism describing some behaviors in very similar ways?

From a clinical perspective, these results suggest that when children show ADHD symptoms primarily in social contexts, it may be valuable to screen for autism symptoms as well. The strong connections between social ADHD symptoms and autism traits indicate these often co-occur.

Limitations and future directions

It’s important to note that this study looked at symptoms in children from the general population, not those with diagnosed ADHD or autism. The patterns of symptom connections may look different in clinical populations with more severe symptoms.

Additionally, the study relied on parent reports of children’s behavior. Future research incorporating teacher reports or direct assessments of children could provide additional insights.

Longitudinal studies examining how these symptom networks change over time as children develop could also be illuminating. Do certain symptoms tend to precede or predict the emergence of others?

Conclusions

• ADHD and autism symptoms largely cluster separately in children from the general population, aligning with traditional diagnostic boundaries.
• However, there are important areas of overlap, particularly for ADHD symptoms that occur in social contexts.
• Some ADHD and autism symptoms may be redundant, potentially reflecting shared underlying causes of social difficulties or similarities in how symptoms are described.
• When evaluating children with social ADHD symptoms, clinicians should consider screening for autism traits as well.

This network approach to understanding ADHD and autism symptom overlap provides a more detailed map of how these conditions relate. Continued research in this vein may lead to more nuanced approaches for assessment and intervention that account for areas of symptom overlap across neurodevelopmental conditions.