How Does the Age of OCD Onset Affect Brain Structure?

What you need to know

• This study examined differences in brain structure between people with early-onset OCD (before age 18) and late-onset OCD (age 18 or later).
• Those with late-onset OCD showed reduced integrity of certain white matter tracts in the brain compared to those with early-onset OCD.
• Late-onset OCD was also associated with less efficient communication between different brain regions.
• These findings suggest that the age when OCD begins may impact how it affects brain structure and function.

Background on OCD and brain imaging

Obsessive-compulsive disorder (OCD) is a mental health condition characterized by recurring, unwanted thoughts (obsessions) and repetitive behaviors (compulsions). It affects about 2% of the world’s population. While we know OCD involves changes in brain structure and function, previous brain imaging studies have shown mixed results.

This study used advanced brain imaging techniques to look at the structure of white matter in the brains of people with OCD. White matter consists of nerve fibers that connect different brain regions, allowing them to communicate. The researchers wanted to see if there were differences based on whether OCD started earlier or later in life.

How the study was conducted

The researchers recruited 260 adults with OCD and 252 healthy control participants from five countries. All OCD participants were free of medication for at least six weeks before the study.

The OCD group was divided into those with early-onset OCD (symptoms started before age 18) and late-onset OCD (symptoms started at 18 or older).

All participants underwent brain scans using diffusion MRI, an imaging technique that allows researchers to examine the structure of white matter tracts in the brain. The researchers then compared the scans between groups.

Key findings

The main findings of the study were:

1. Late-onset OCD was associated with reduced integrity of white matter tracts, particularly in an area called the posterior thalamic radiation. This tract connects the thalamus (a relay center in the brain) to areas in the back of the brain involved in visual processing and attention.

2. People with late-onset OCD showed lower “global efficiency” in their brain’s structural network. This suggests the different regions of their brains may not communicate as effectively with each other.

3. The early-onset and late-onset OCD groups showed opposite patterns when compared to healthy controls. The early-onset group tended to have higher white matter integrity in certain areas, while the late-onset group had lower integrity.

4. There were no significant differences in overall white matter structure between all OCD participants combined and healthy controls.

What do these findings mean?

These results suggest that the age when OCD first develops may impact how it affects brain structure. The differences seen in white matter integrity and brain network efficiency could reflect different underlying causes or developmental processes in early-onset versus late-onset OCD.

The findings related to the posterior thalamic radiation are particularly interesting. This brain area is involved in visual processing and attention. Some researchers have suggested that altered visual and attentional processes may play a role in OCD symptoms, such as the urge to check things repeatedly.

The opposite patterns seen in early-onset versus late-onset OCD compared to healthy controls are intriguing. It’s possible that OCD developing at different life stages may disrupt normal brain maturation processes in distinct ways. However, more research is needed to understand the exact mechanisms involved.

Limitations and future directions

While this study provides valuable insights, there are some limitations to consider:

• The study only looked at brain structure at one point in time. Following people over time as OCD develops could provide more information about how and why these differences occur.

• The categorization of early-onset versus late-onset at age 18 is somewhat arbitrary. Future studies might examine age of onset as a continuous variable or look at finer age categories.

• While participants were medication-free during the study, past medication use could potentially impact brain structure.

Future research could:

• Investigate how these structural brain differences relate to specific OCD symptoms or treatment outcomes.
• Combine structural imaging with functional brain imaging to better understand how these changes impact brain activity.
• Include younger participants to examine how OCD may affect brain development during childhood and adolescence.

Conclusions

• The age when OCD first develops appears to impact how it affects brain structure, particularly white matter tracts.
• Late-onset OCD is associated with reduced integrity of certain white matter tracts and less efficient communication between brain regions.
• These findings highlight the importance of considering age of onset when studying OCD and may eventually help inform more personalized treatment approaches.
• More research is needed to understand the mechanisms behind these differences and their clinical implications.