How Do People with OCD and Schizophrenia Differ in Recognizing Their Own Thoughts?

What you need to know

Both people with OCD and schizophrenia have difficulty recognizing their own thoughts compared to healthy individuals
Only people with schizophrenia struggle to distinguish between imagined and real events
These differences in thought recognition may help explain some key symptoms of each disorder

Understanding our own thoughts

Have you ever had trouble remembering if you actually locked the front door, or just thought about locking it? This ability to recognize the source of our thoughts and memories is called “source monitoring.” It’s an important cognitive skill that most of us use without even realizing it.

However, for people with certain mental health conditions like obsessive-compulsive disorder (OCD) or schizophrenia, source monitoring can be challenging. This can lead to symptoms like intrusive thoughts or false beliefs. A recent study set out to compare how source monitoring differs between people with OCD, people with schizophrenia, and people without these conditions.

What is source monitoring?

Source monitoring refers to the mental processes we use to figure out where our thoughts, memories and beliefs came from. There are a few different types of source monitoring:

Internal source monitoring: Distinguishing between thoughts we had versus actions we took. For example, did I actually turn off the stove, or did I just think about turning it off?
Reality monitoring: Distinguishing between things we imagined versus things that really happened. For example, did my friend actually tell me that story, or did I dream it?
External source monitoring: Distinguishing between different external sources of information. For example, did I hear that news from my neighbor or read it in the newspaper?

Most people are able to do these types of source monitoring fairly easily in everyday life. But for those with certain mental health conditions, it can be more difficult.

How the study worked

To compare source monitoring abilities, researchers recruited three groups of participants:

32 people diagnosed with OCD
38 people diagnosed with schizophrenia
29 healthy individuals without these diagnoses

All participants completed two source monitoring tasks:

Internal source monitoring task: Participants saw words on a screen. For some words, they were instructed to say the word out loud. For others, they were told to imagine saying the word. Later, they had to identify whether they had actually said each word out loud, imagined saying it, or if it was a new word they hadn’t seen before.
Reality monitoring task: Similar to the first task, but this time participants either heard words spoken aloud or were instructed to imagine hearing the words. Later they had to identify if they had actually heard each word, imagined hearing it, or if it was new.

Key findings

The study revealed some important differences in how the three groups performed:

Internal source monitoring

Both the OCD group and schizophrenia group had more difficulty with the internal source monitoring task compared to the healthy control group. Specifically, they were less able to recognize words they had imagined saying versus actually said out loud.

However, the deficit was more severe in the schizophrenia group than the OCD group. We can think of it as a spectrum:

Healthy controls > OCD group > Schizophrenia group

This suggests that difficulty distinguishing between thoughts and actions may be a shared feature of both OCD and schizophrenia, but to different degrees.

Reality monitoring

Only the schizophrenia group showed impairment on the reality monitoring task. They had more trouble distinguishing between words they had actually heard versus words they had imagined hearing.

The OCD group performed similarly to healthy controls on this task. This indicates that people with OCD don’t have difficulty distinguishing imagined events from real ones, while those with schizophrenia do struggle with this.

What does this mean?

These findings help shed light on the cognitive processes underlying symptoms of OCD and schizophrenia:

For OCD

People with OCD showed a specific difficulty with internal source monitoring - distinguishing between thoughts and actions. This maps onto a core symptom of OCD: intrusive thoughts and doubt about whether an action was completed.

For example, someone with OCD might have trouble distinguishing between the thought “I should check if the door is locked” and the memory of actually checking the lock. This uncertainty can fuel the compulsion to check repeatedly.

However, people with OCD did not show impairment in reality monitoring. This fits with the fact that people with OCD generally recognize that their obsessive thoughts are coming from their own mind, even if they can’t control them.

For schizophrenia

People with schizophrenia showed deficits in both internal source monitoring and reality monitoring. This more severe and widespread difficulty in recognizing the source of thoughts may contribute to symptoms like delusions and hallucinations.

For instance, trouble with reality monitoring could lead someone to believe an imagined voice was real (auditory hallucination). Difficulty with internal source monitoring might cause them to believe their own thoughts are being inserted into their mind by an outside force (thought insertion delusion).

Implications for treatment

Understanding these cognitive differences could potentially lead to more targeted treatments for OCD and schizophrenia:

For OCD, interventions focused specifically on improving internal source monitoring might help reduce doubt and repetitive checking behaviors.
For schizophrenia, broader cognitive remediation addressing both internal source and reality monitoring might help patients better distinguish between internal and external stimuli.
The fact that people with OCD maintain intact reality monitoring abilities suggests they may be more responsive to reality-based cognitive therapies compared to people with schizophrenia.

Limitations and future directions

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

The sample sizes were relatively small, so larger studies are needed to confirm the findings.
The study didn’t account for different subtypes of OCD or schizophrenia, which could impact source monitoring abilities.
Medication use wasn’t controlled for, which could potentially affect cognitive performance.

Future research could explore:

How source monitoring abilities relate to specific symptoms in OCD and schizophrenia
Whether source monitoring training could improve symptoms
How these cognitive differences develop over the course of the disorders
The neural mechanisms underlying these source monitoring differences

Conclusions

Both OCD and schizophrenia involve difficulties recognizing the source of one’s own thoughts, but in different ways
People with OCD struggle specifically with distinguishing thoughts from actions
People with schizophrenia have broader difficulties distinguishing thoughts from actions AND imagination from reality
These cognitive differences may help explain core symptoms of each disorder
Understanding these distinctions could lead to more targeted treatments in the future

While there’s still much to learn, this research provides valuable insights into the cognitive processes underlying OCD and schizophrenia. It highlights how two disorders with some overlapping symptoms can still involve distinct patterns of cognitive functioning. Continued research in this area may help improve our understanding and treatment of these challenging conditions.