How Do Obsessive-Compulsive Symptoms Affect Brain Networks in Children?

What you need to know

• This study examined how obsessive-compulsive symptoms relate to brain network characteristics in children from the general population.
• Children with at least one obsessive-compulsive symptom showed differences in overall brain network organization and connectivity between certain brain regions compared to children without symptoms.
• The findings suggest that even mild obsessive-compulsive symptoms in children may be associated with subtle differences in brain function and communication.

Background on obsessive-compulsive symptoms

Obsessive-compulsive disorder (OCD) is a mental health condition characterized by recurring, intrusive thoughts (obsessions) and repetitive behaviors or mental acts (compulsions) that a person feels compelled to perform. While OCD is typically diagnosed in adolescence or adulthood, milder obsessive-compulsive symptoms (OCS) are common in children and may predict future development of OCD.

Previous brain imaging studies in people with diagnosed OCD have found differences in the structure and function of certain brain regions and networks. However, less is known about whether children with milder OCS from the general population show any brain differences compared to children without symptoms.

How the brain is organized into networks

The human brain is organized into interconnected networks of regions that work together to perform various functions. We can think of these networks like subway systems in a city - different lines (networks) connect various stations (brain regions) to efficiently transport people (or in this case, information) throughout the system.

Some key concepts for understanding brain network organization include:

• Nodes: Individual brain regions or “stations” in the network
• Edges: Connections between nodes, like subway lines between stations
• Modules: Groups of highly interconnected nodes that work closely together, like neighborhoods connected by local transit lines
• Hubs: Highly connected nodes that link different modules, like major transit hubs connecting different subway lines

Neuroscientists can examine how these networks are organized and communicate using brain imaging techniques like functional magnetic resonance imaging (fMRI). This allows them to create maps of brain connectivity and calculate various measures of network structure and function.

What this study examined

This study used fMRI to look at brain network characteristics in 1,701 children aged 9-12 years from the general population. The researchers were particularly interested in how obsessive-compulsive symptoms related to:

1. Global network topology: The overall organization of brain networks
2. Subnetwork connectivity: Communication between different functional brain networks
3. Thalamus network participation: How a key brain structure called the thalamus participates in network communication

The thalamus is an important relay center in the brain that helps coordinate information flow between different regions. Previous studies have found differences in thalamus structure and function in people with OCD.

Obsessive-compulsive symptoms were measured using a parent-reported questionnaire called the Short Obsessive-Compulsive Disorder Screener (SOCS).

Key findings

The initial analyses comparing children with probable OCD (based on questionnaire scores) to those without symptoms did not find any significant differences in brain network measures.

However, when the researchers looked at children who had at least one obsessive-compulsive symptom compared to those with no symptoms, they found several differences:

1. Higher modularity in children with OCS

Children with at least one obsessive-compulsive symptom showed higher modularity in their overall brain network organization. Modularity refers to how easily a network can be divided into separate communities or modules.

Higher modularity suggests the brain may be organized into more distinct, segregated subnetworks in children with OCS. This could potentially reflect less flexible communication between different brain systems.

2. Reduced connectivity between certain networks

Children with OCS symptoms showed lower connectivity between three key brain networks:

• The frontoparietal network - involved in attention and cognitive control
• The limbic network - involved in emotion and motivation
• The visual network - processes visual information

Reduced communication between these networks could potentially contribute to some of the attentional, emotional, and perceptual symptoms seen in OCD.

3. Altered thalamus network participation

Children with OCS showed differences in how a specific part of the thalamus (the lateral prefrontal region) participated in brain networks. This thalamic region had a lower “within-module degree Z-score,” suggesting its connections were more dispersed across different brain modules rather than concentrated within its own module.

This altered thalamus connectivity aligns with previous research implicating thalamus function in OCD. The thalamus plays an important role in coordinating information flow throughout the brain, so differences in its network participation could have widespread effects.

Conclusions

• Even mild obsessive-compulsive symptoms in children from the general population may be associated with subtle differences in brain network organization and communication.
• The brain differences were only apparent when comparing children with at least one OC symptom to those with no symptoms, rather than only in children meeting criteria for probable OCD. This suggests brain alterations may occur along a continuum with symptom severity.
• The specific network differences found, including altered modularity, reduced connectivity between attention/emotion networks, and differences in thalamus network participation, provide new insights into potential brain mechanisms underlying obsessive-compulsive symptoms.

Implications and future directions

This study adds to our understanding of the relationship between obsessive-compulsive symptoms and brain function, even in children from the general population who do not necessarily have diagnosed OCD. The findings suggest that brain network alterations may emerge early in the course of symptom development.

However, it’s important to note that this study only shows associations - we can’t conclude that the brain differences directly cause obsessive-compulsive symptoms or vice versa. The relationship is likely complex and bidirectional.

More research is needed to:

1. Determine if these brain network characteristics predict future development of OCD
2. Clarify how specific symptom types (e.g. contamination fears vs. checking compulsions) relate to different patterns of brain connectivity
3. Investigate whether interventions targeting brain network function could help prevent or treat obsessive-compulsive symptoms

Understanding the brain basis of OCS, even at low levels, may eventually help guide more targeted and effective treatments. However, much more work is needed before these findings can be applied clinically.

It’s also crucial to remember that some degree of obsessive or compulsive tendencies can be a normal part of child development. Parents should not be alarmed if their child shows occasional repetitive behaviors or worries. If symptoms are frequent, intense, or interfering with daily life, consulting a mental health professional is recommended.

By shedding light on the complex relationship between brain function and obsessive-compulsive symptoms, this study takes us one step closer to unraveling the neurobiology of OCD. Continued research in this area holds promise for improving our ability to identify, prevent, and treat obsessive-compulsive symptoms across the lifespan.