Authors: Lianqing Zhang; Xinyu Hu; Lu Lu; Bin Li; Xiaoxiao Hu; Xuan Bu; Hailong Li; Shi Tang; Yingxue Gao; Yanchun Yang; John A. Sweeney; Qiyong Gong; Xiaoqi Huang · Research
How Does the Amygdala's Structure Differ in People With Obsessive-Compulsive Disorder?
Research reveals key differences in amygdala structure between people with OCD and healthy individuals, with implications for understanding symptoms.
Source: Zhang, L., Hu, X., Lu, L., Li, B., Hu, X., Bu, X., Li, H., Tang, S., Gao, Y., Yang, Y., Sweeney, J. A., Gong, Q., & Huang, X. (2020). Anatomic alterations across amygdala subnuclei in medication-free patients with obsessive–compulsive disorder. Journal of Psychiatry and Neuroscience, 45(5), 334-343. https://doi.org/10.1503/jpn.190114
What you need to know
- The amygdala, a brain region involved in emotion and behavior, shows reduced volume in people with OCD compared to those without the disorder
- The central nucleus of the amygdala, which helps with behavioral flexibility, shows the most significant reduction in size
- Changes in different parts of the amygdala may contribute to various OCD symptoms, including inflexible behaviors, anxiety, and certain types of obsessions
Understanding the Amygdala and OCD
The amygdala is a complex structure in the brain made up of several distinct regions, each with specialized functions. This study examined how these different regions might be altered in people with OCD, providing new insights into how brain structure relates to symptoms.
Key Regions and Their Functions
The Central Nucleus
The central nucleus of the amygdala (CeA) plays a crucial role in helping us adapt our behavior based on outcomes. When things don’t go as expected, this region helps us adjust our behavior accordingly. The study found this region showed the largest volume reduction (11-13%) in people with OCD. This finding suggests that when this area isn’t working optimally, it may be harder for people with OCD to shift away from repetitive behaviors, even when those behaviors aren’t helpful.
The Basolateral Complex
The basolateral complex (BLA) helps process fear and emotion. It showed smaller but still significant volume reductions (3-9%) in people with OCD. This region’s alterations may contribute to heightened fear responses and emotional reactivity often seen in OCD.
Other Important Regions
The study also found volume reductions in other amygdala regions:
- The medial nucleus (involved in processing aggression and sexual behavior)
- The cortical nucleus (connected to smell processing)
These changes might help explain why some people with OCD experience specific types of symptoms, such as aggressive obsessions or contamination fears.
Clinical Implications
The researchers discovered several important relationships between brain structure and symptoms:
- Longer illness duration was associated with smaller volume in the right central nucleus, suggesting the condition might have progressive effects on brain structure
- Changes in the medial nucleus showed complex relationships with symptoms - smaller volume was linked to more obsessive thoughts but fewer compulsive behaviors
Conclusions
- The amygdala shows consistent structural differences in people with OCD compared to those without the disorder
- Different regions of the amygdala show varying degrees of volume reduction, which may explain different aspects of OCD symptoms
- These findings support including the amygdala in our understanding of OCD’s brain circuits, beyond the traditional focus on frontal-striatal pathways