The difference between obsession and delusion

Animals cannot talk, so when they’re used as test subjects in scientific experiments, researchers have to study their behavior patterns to make sense of their activities.

Similarly, researchers at Tel Aviv University are now using these zoological methods to study humans who have serious mental disorders.

For the study, researchers compared symptoms between patients with obsessive-compulsive disorder (OCD) and “schizo-OCD” (a combination of schizophrenia and OCD symptoms) by recording the patients as they performed basic tasks.

By analyzing the patients’ movements, they were able to identify similarities and differences between two frequently confused disorders.

The findings of the study, published in the journal CNS Spectrums, helps to resolve a longstanding question about the nature of schizo-OCD: Is it a combination of OCD and schizophrenia, or a variation of just one of the disorders?

The researchers concluded that schizo-OCD is a combination of the two disorders, noting that the behavioral differences identified in the study could be used to help diagnose patients with OCD and other obsessive-compulsive disorders, including schizo-OCD.

“I realized my methodology for studying rat models could be directly applied to work with humans with mental disorders,” said Prof. David Eilam of TAU’s Zoology Department at The George S. Wise Faculty of Life Sciences.

“Behavior is the ultimate output of the nervous system, and my team and I are experts in the fine-grained analysis of behavior, be it of humans or of other animals,” Prof. Eilam added.

People with OCD feel the need to check things repeatedly, or have certain thoughts or perform routines and rituals over and over. The main features of OCD are obsessions and compulsions. Obsessions are recurring and persistent thoughts, impulses, or images that are intrusive and cause significant distress or anxiety.

On the other hand, compulsions are repetitive motor behaviors (such as counting) that occur in response to obsessions and are performed according to strictly applied rules. Schizophrenia is marked by symptoms that include delusions, hallucinations, disorganized speech, abnormal motor behavior, and diminished emotional expression.

In an effort to determine whether schizo-OCD is a combination of OCD and schizophrenia, or a variation of just one of the disorders, Prof. Eilam and a team of researchers launched a study to resolve the longstanding question.

Accordingly, they recorded and compared videos of diagnosed OCD and schizo-OCD patients performing 10 different mundane tasks, such as leaving home, making tea, or cleaning a table.

The researchers found that both OCD and schizo-OCD patients exhibited OCD-like behavior in performing the tasks, excessively repeating and adding actions. However, the schizo-OCD patients also acted like schizophrenics while exhibiting OCD-like behavior.

For a typical OCD patient in the study, the task of leaving home involved standing in one place and repeatedly checking the contents of his pockets before finally taking his keys and cell phone and going to the door.

However, a typical schizo-OCD patient traveled around the apartment, switching lights in the bathroom on and off, then taking keys and phone to the door before going to scan the bedroom, then taking his keys and phone to the door before going to empty the ashtray, and then again taking his keys and phone to the door (and so on and so forth).

By contrast, a typical healthy person would simply pick up his keys and phone and walk out.

Overall, the researchers found that the level of obsessive-compulsive behavior was the same in OCD and schizo-OCD patients, which suggests that both types of patients had difficulty shifting attention from one task to another – a symptom that helps define OCD.

However, the schizo-OCD patients did more divergent activity over a larger area than did OCD patients, which suggests that the schizo-OCD patients were continuously shifting attention, which happens in schizophrenia, but not OCD.

“While the obsessive compulsive is obsessed with one idea; the schizophrenic’s mind is drifting,” said Eilam. “We found that this is reflected in their paths of locomotion. So instead of tracking the thoughts of the patients, we can simply trace their paths of locomotion.”

SOURCE: American Friends of Tel Aviv University. “The difference between obsession and delusion – zoological method to classify symptoms of OCD and schizophrenia in humans.” (September 4, 2013)