Scientists have uncovered the mechanism of the gap between thoughts and actions in OCD

People with obsessive-compulsive disorder may realize that their actions are illogical or excessive, but at the same time have difficulty stopping them. A new study has shown that this feature may be related to impaired interaction between brain regions involved in conflict detection and behavior control. What happens with OCD and why it can be difficult for a person to act contrary to an automatic reaction is in the Izvestia article.

The study showed a difference in behavior

Scientists from the South China Normal University, Ningbo University and Shenzhen University studied how people with OCD make decisions in situations where the automatic reaction conflicts with the goal. The study involved 36 people with obsessive-compulsive disorder and 37 healthy participants in the control group. The researchers used a behavioral task, computer modeling, and electroencephalography. The work was published in the journal PLOS Biology.

During the experiment, the participants were shown visual signals and asked to press one of the buttons depending on them or, conversely, refrain from action. Some signals were associated with the opportunity to receive a reward, others with the need to avoid a loss. In this way, scientists created situations in which a person's automatic desire to get a positive result or avoid a negative one could contradict the correct action according to the rules of the task.

Both groups were generally able to master the rules of the experiment. However, participants with OCD had a stronger so—called Pavlovian bias, an automatic tendency to respond to an attractive or unpleasant stimulus in a certain way. In addition, people with OCD were slower to learn to suppress the wrong reaction in cases where it was necessary to refrain from action. Computer simulations also showed a stronger dependence of behavior on motivational signals and a lower learning rate.

However, the results did not mean that people with OCD did not notice the contradiction between their behavior and the goal at all. On the contrary, brain activity has shown that they are capable of detecting such conflict. The main difference was that the signal that should help them adjust the action occurred at a different time and had a worse effect on the subsequent choice.

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What is OCD and why do obsessive actions occur?

Obsessions can be different. For example, a person may be haunted by the fear of getting infected, forgetting something important, losing control of themselves, or harming another. Some people have obsessive thoughts about forbidden or frightening topics, while others have a strong need for symmetry, order, or the feeling that everything is done "right."

Compulsions often become a reaction to such thoughts. A person can constantly wash their hands, check the lock or turn off the stove, count objects, put things in a certain order, or repeat words and phrases to themselves. At the same time, performing the ritual usually does not bring pleasure, but rather temporarily reduces anxiety or an unpleasant feeling, after which the obsession may return.

This is where one of the characteristic features of OCD appears: a person may realize that his action is excessive or does not make rational sense, but still feel a strong desire to carry it out. For example, he may know that the door is already locked, but return to the lock again and again to check. In the scientific literature, this feature is called dissociation between understanding and action.

OCD differs from the usual habit of double-checking what has been done or striving for cleanliness precisely by the severity of the symptoms. According to the US National Institute of Mental Health, a person with the disorder is often unable to control obsessions or compulsions, spends a significant amount of time on them and experiences serious problems in their daily lives because of them.

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How the concept of OCD appeared

Obsessive thoughts and repetitive actions were described by doctors back in the 19th century, but for a long time they were not considered as an independent mental disorder. French and German psychiatrists explained the origin of such conditions in different ways: some associated them primarily with disorders of the emotional sphere and will, others with the peculiarities of intellectual activity. Only gradually did obsessions begin to be isolated into a separate clinical phenomenon.

One of the key stages was the work of the German psychiatrist and neurologist Karl Westphal, published in 1877. He used the term zwangsvorstellung ("obsession" or "forced idea") and was one of the first to give a clear description of obsessions as an independent psychopathological phenomenon. It was his work that laid the foundation for the further formation of modern diagnostic criteria for obsessive-compulsive disorder.

Subsequently, the terminology continued to evolve. In the UK, the German concept began to be translated by the word obsession ("obsession"), and in the USA the word compulsion became widespread. The modern name obsessive-compulsive disorder ("obsessive-compulsive disorder") was formed later as a combination of both concepts.

In the late 19th and early 20th centuries, Pierre Janet, Emile Kraepelin and Sigmund Freud also made significant contributions to the study of the disorder, offering their own explanations of the nature of obsessions and compulsions. Although many of their ideas have been revised today, it was these works that helped to form OCD as an independent diagnostic category.

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What happens in the brain during OCD

To find out why OCD creates a gap between understanding the situation and acting, the scientists studied the electrical activity of the participants' brains during the task. They paid special attention to the theta rhythm, fluctuations in brain activity in the range of 4-8 Hz. Such a rhythm in the area of the middle frontal cortex is associated with the detection of conflict and the need to activate cognitive control.

In healthy participants, when a conflict occurred, the activity of the middle frontal region of the brain increased, and then its synchronization with other areas, including the motor cortex, increased. In a simplified way, this process can be represented as a chain: the brain detects that an automatic reaction does not meet the goal, and then transmits a signal to the systems that must adjust the action.

In people with OCD, the very ability to detect conflict persisted. The researchers also registered an increase in theta activity in them when the automatic reaction contradicted the rules of the task. However, the time characteristics of the signal differed: in healthy participants, increased theta activity occurred before the action was performed, while in people with OCD, the corresponding period partially coincided with the moment of reaction. At the same time, participants with OCD were not found to have a reliable increase in theta activity immediately before the response, which was observed in the control group.

Even more important was the interaction between the brain regions. In healthy people, the synchronization of theta activity between the middle frontal and motor regions increased during conflict. Participants with OCD did not experience such an increase. The researchers' model showed that it was this connection that best explained the ability to regulate automatic motivational responses.

Thus, the results suggest that the problem with OCD may not be a lack of understanding of the situation. A person is able to notice that his automatic reaction does not correspond to the goal, but the mechanism of transmitting this signal to the systems responsible for changing behavior is less effective. The authors believe that the disruption of synchronization between the middle frontal and motor areas may be one of the neural mechanisms underlying the gap between understanding and action characteristic of OCD. The authors note that the discovered mechanism may be considered in the future as a potential target for developing new treatment approaches, but the work itself did not test the effectiveness of any treatment.