Can Decision-Making Patterns Reveal Risk for Obsessive-Compulsive Disorder?

What you need to know

• The study examined differences in decision-making patterns between people with obsessive-compulsive disorder (OCD), their unaffected siblings, and healthy controls.
• OCD patients showed some subtle differences in decision-making compared to healthy controls, but the differences were not as pronounced as in previous studies.
• Brain imaging revealed that certain brain regions involved in decision-making showed different patterns of activity in OCD patients and their siblings compared to healthy controls.
• The findings suggest that altered activity in these brain regions may be a potential risk factor for developing OCD.

Understanding decision-making in OCD

Obsessive-compulsive disorder (OCD) is a mental health condition characterized by persistent, intrusive thoughts (obsessions) and repetitive behaviors or mental acts (compulsions). While the exact causes of OCD are not fully understood, researchers believe that both genetic and environmental factors play a role.

Recent theories suggest that people with OCD may have an imbalance between two different types of decision-making strategies:

1. Model-based control: A flexible, goal-directed approach that considers the consequences of actions.
2. Model-free control: A more automatic, habitual approach based on past experiences.

Previous studies have found that people with OCD tend to rely more on model-free control and less on model-based control compared to healthy individuals. However, it was unclear whether this difference in decision-making strategies might be a potential risk factor for developing OCD.

To investigate this question, researchers conducted a study examining decision-making patterns in three groups:

1. People diagnosed with OCD
2. Unaffected siblings of OCD patients
3. Healthy controls with no family history of OCD

The two-step task: A window into decision-making

The study used a computer-based test called the “two-step task” to measure how participants made decisions. In this task, participants make a series of choices between different options, with the goal of earning rewards. The task is designed to distinguish between model-based and model-free decision-making strategies.

Here’s how the task works:

1. Participants see two images and choose one.
2. Their choice leads to a second set of images, where they make another choice.
3. After the second choice, they may or may not receive a reward.
4. The likelihood of reaching certain second-stage options and receiving rewards changes over time.

By analyzing how participants make choices in this task, researchers can determine whether they are using more model-based or model-free strategies.

Subtle differences in decision-making

Contrary to the researchers’ expectations, the study did not find strong evidence for a shift towards model-free control in OCD patients compared to healthy controls. However, there were some subtle differences:

1. OCD patients showed a trend towards lower scores on a measure of model-based control, but this difference was not statistically significant.
2. When examining reaction times, OCD patients showed less distinction between expected and unexpected outcomes compared to healthy controls and unaffected siblings. This suggests they may have a weaker understanding of the task structure, which is important for model-based decision-making.

Interestingly, unaffected siblings showed some differences in their decision-making patterns as well:

1. Siblings had reaction time patterns that were intermediate between OCD patients and healthy controls.
2. In some measures, siblings actually showed higher levels of model-based control than healthy controls.

These findings suggest that alterations in decision-making strategies may be related to the risk of developing OCD, but the relationship is complex and not as straightforward as initially thought.

Brain imaging reveals potential risk factors

In addition to the behavioral task, the researchers also conducted brain imaging scans on most of the participants. They found some interesting differences in brain structure and function that were related to decision-making patterns:

1. Surface area of prefrontal cortex: Across all participants, the surface area of certain regions in the prefrontal cortex was positively correlated with model-based decision-making. The prefrontal cortex is involved in planning, reasoning, and goal-directed behavior.

2. Volume of striatum: The researchers found different relationships between the volume of a brain region called the striatum and decision-making patterns in each group:

   • In OCD patients and unaffected siblings, larger striatum volume was associated with less model-based control.
   • In healthy controls, larger striatum volume was associated with more model-based control.

The striatum is part of the brain’s reward system and is involved in learning and decision-making. These findings suggest that the relationship between brain structure and decision-making may be altered in people with OCD and their close relatives.

Implications for understanding OCD risk

While the study did not find dramatic differences in decision-making between OCD patients and healthy controls, the subtle alterations observed in both patients and their unaffected siblings provide valuable insights:

1. Potential endophenotype: The differences in brain structure and function related to decision-making may represent an “endophenotype” for OCD. An endophenotype is a measurable characteristic that is associated with a disorder and is present in both affected individuals and their unaffected relatives.

2. Complex relationship: The findings suggest that the relationship between decision-making strategies and OCD risk is more complex than previously thought. Simply having a bias towards model-free control may not be sufficient to explain OCD symptoms.

3. Role of brain structure: The alterations in how brain structure relates to decision-making in OCD patients and their siblings highlight the importance of understanding the neurobiological basis of the disorder.

Limitations and future directions

It’s important to note some limitations of this study:

1. Sample size: The study included relatively small groups, which may have limited its ability to detect some differences between groups.

2. Medication effects: Most of the OCD patients were taking medication, which could have influenced their decision-making patterns.

3. Cross-sectional design: The study only looked at participants at one point in time, so it cannot determine whether the observed differences in decision-making and brain structure actually lead to the development of OCD.

Future research could address these limitations by:

1. Studying larger groups of participants
2. Following people over time to see how decision-making patterns relate to the development of OCD symptoms
3. Examining decision-making in medication-free OCD patients

Conclusions

• People with OCD show subtle differences in decision-making patterns compared to healthy controls, particularly in how they process unexpected outcomes.
• Unaffected siblings of OCD patients also show some alterations in decision-making, suggesting these patterns may be related to OCD risk.
• Differences in how brain structure relates to decision-making in OCD patients and their siblings may represent a potential risk factor or “endophenotype” for the disorder.
• Understanding these decision-making patterns and their neurobiological basis could lead to new ways of identifying people at risk for OCD and developing targeted interventions.