How Does the Amygdala Function Differently in People with OCD?

What you need to know

• The amygdala, a brain region involved in processing emotions, functions differently in people with OCD compared to those without.
• Two parts of the amygdala - the basolateral and centromedial regions - show altered connections to other brain areas in OCD.
• These connectivity differences may help explain some of the emotional and behavioral symptoms of OCD.

The amygdala’s role in emotions and behavior

The amygdala is a small, almond-shaped structure deep within the brain that plays a key role in processing emotions, particularly fear and anxiety. It helps us detect potential threats in our environment and respond appropriately. The amygdala doesn’t work alone - it constantly communicates with many other brain regions to integrate emotional information with our thoughts and behaviors.

Recent research suggests the amygdala may function differently in people with obsessive-compulsive disorder (OCD), potentially contributing to some of the disorder’s characteristic symptoms like persistent intrusive thoughts and repetitive behaviors. However, the details of how exactly amygdala function differs in OCD have remained unclear.

A new study published in Communications Biology sheds light on this question by examining the functional connections between different parts of the amygdala and other brain regions in people with and without OCD. The researchers used advanced brain imaging and analysis techniques to map out these connections in detail.

A tale of two amygdalae

The amygdala can be divided into two main subregions:

1. The basolateral amygdala (BLA): This area receives sensory information from other parts of the brain and is involved in learning associations between stimuli and emotional responses.

2. The centromedial amygdala (CMA): This region is considered the main output center of the amygdala, sending signals to other parts of the brain to generate behavioral and physiological responses to emotional stimuli.

In people without OCD, the study found that the BLA tends to have stronger connections to several other brain regions compared to the CMA. These regions include:

• The insula: An area involved in processing internal bodily sensations and integrating them with external information
• The supplementary motor area (SMA): A region that helps plan and execute movements
• The midcingulate cortex (MCC): An area involved in decision making and action selection
• The superior temporal gyrus (STG): A region that processes auditory information and is involved in language comprehension
• The postcentral gyrus (PCG): The primary sensory area for touch sensations from the body

However, in people with OCD, this pattern was reversed - the CMA showed stronger connections to these regions than the BLA did.

Connectivity differences in OCD

The researchers found several specific differences in amygdala connectivity between people with OCD and those without:

1. Reduced connectivity between the left BLA and left insula in OCD. This could potentially contribute to difficulties in integrating bodily sensations with emotional information.

2. Increased connectivity between the right CMA and several regions (SMA, MCC, insula, STG, and PCG) in OCD. This might lead to an overemphasis on behavioral and physiological responses to emotional stimuli.

3. Smaller volume of the left BLA and right CMA in people with OCD. This structural difference accompanied the functional connectivity changes.

What might these differences mean?

These alterations in amygdala connectivity could help explain some of the symptoms and behaviors characteristic of OCD:

1. Difficulties with emotional processing: The changed connections between the amygdala and insula might contribute to problems integrating emotional information with bodily sensations and external stimuli. This could potentially relate to the heightened anxiety and distress often experienced by people with OCD.

2. Overactive behavioral responses: The increased connectivity between the CMA (the amygdala’s main output region) and areas involved in planning and executing movements (like the SMA) might contribute to the compulsive behaviors often seen in OCD.

3. Altered sensory processing: Changes in connectivity with regions like the STG and PCG suggest that the way sensory information is integrated with emotional processing might be different in OCD. This could potentially relate to the heightened sensitivity to certain stimuli that some people with OCD experience.

4. Decision-making difficulties: The altered connections with the MCC, an area involved in decision making, might contribute to the difficulties with indecision or “paralysis of analysis” that some people with OCD experience.

Implications for understanding and treating OCD

This research provides new insights into how brain function differs in people with OCD, particularly in terms of how emotional information is processed and integrated with other brain functions. Understanding these differences could potentially lead to new treatment approaches in the future.

For example, therapies that specifically target the function of the amygdala or its connections with other brain regions might be developed. Existing treatments like cognitive-behavioral therapy might be refined to better address the specific patterns of brain function seen in OCD.

It’s important to note that while this study found clear differences in amygdala function between people with and without OCD, it doesn’t tell us whether these differences cause OCD symptoms or result from them. More research will be needed to fully understand the relationship between these brain differences and the symptoms of OCD.

Conclusions

• The amygdala, a key brain region for processing emotions, shows altered patterns of connectivity with other brain regions in people with OCD.
• These differences involve both main subregions of the amygdala - the basolateral and centromedial areas - and affect connections with regions involved in sensory processing, movement planning, and decision making.
• Understanding these brain differences may lead to new insights into the mechanisms underlying OCD and potentially to new treatment approaches in the future.