Obsessive-compulsive disorder is one of the psychological disorders that involves the control of unwanted obsessive thoughts that force a person into compulsive behaviors in the hope of getting rid of these obsessions and the anxiety associated with them. The causes of obsessive-compulsive disorder may be due to a group of genetic, biological, and environmental factors that lead to the onset of symptoms in late childhood or early adolescence, and it can also occur in the early twenties.
In this article, learn about all the causes of obsessive-compulsive disorder and the risk factors that increase the possibility of developing it.
Causes of obsessive-compulsive disorder
The exact causes are not known, but it is believed that this disorder could be due to genetic causes, or as a result of changes in the vital functions of the brain, and may even result from cognitive and behavioral factors. 
The following are the main causes of obsessive-compulsive disorder:
One of the causes of obsessive-compulsive disorder in adolescents and children is the presence of genetic factors. It has been observed that it is inherited in families, as it was found that a person with obsessive-compulsive disorder is often affected by one of his family members, whether it is a parent or a sibling, and the possibility of infection increases in identical twins more than Non-identical twins. Obsessive-compulsive disorder that begins in childhood is usually attributed to genetic causes, but the genes responsible for it have not yet been identified.  
It should be noted that certain types of obsessive-compulsive disorder often spread in the same family, such as obsessive hygiene, hoarding, counting and examination, and others. 
The causes of obsessive-compulsive disorder may be due to differences in brain activity, structure, and function in people with this disorder. These differences include the way information is transmitted from the brain to the body and back, the way emotions are processed, and the control of signals.
It was also observed that there was an overactivity of different parts of the brain involved in emotions, decision-making, cognitive function, and motor control. 
Chemical changes in the brain
It is likely that a lack of serotonin in the brain is one of the causes of obsessive-compulsive disorder, as it was found that the level of people with obsessive-compulsive disorder is lower than normal. In addition, it has been proven that antidepressants that work to increase the level of serotonin in the brain, such as selective serotonin reuptake inhibitors, improve symptoms. Obsessive-compulsive disorder. 
It is also likely that the cause of obsessive-compulsive disorder may be due to the person’s misinterpretation of his thoughts, as the individual usually ignores the bad or unacceptable thoughts that come to his mind, while in other cases the person may be controlled by the fear of the occurrence of these bad thoughts, and even continues to chase him until they become an obsession that makes him convinced of the possibility of their occurrence; Which forces him to take compulsive actions to prevent the danger he fears. 
One of the reasons for obsessive-compulsive disorder may be that the person learns certain rituals that he repeats in order to avoid fear associated with certain situations or things and to reduce the danger. 
This can happen because a person has been exposed to a trauma or psychological crisis that is accompanied by a period of intense, followed by an attempt to avoid this trauma and all its associated feelings of fear and anxiety by performing certain actions and behaviors, and this is more common in those who have a genetic predisposition to develop obsessive-compulsive disorder . 
Risk factors for obsessive-compulsive disorder
There are many factors that may increase the likelihood of developing obsessive-compulsive disorder and stimulate the emergence of its symptoms, and examples of these factors include the following:  
- Exposure to psychological pressure or trauma: Exposure to severe nervous pressure can increase the risk of obsessive-compulsive disorder, and psychological pressure is one of the reasons for increasing obsessive-compulsive disorder and exacerbating its symptoms.
- Exposure to abuse or violence in childhood: One of the causes of obsessive-compulsive disorder and fear is exposure to abuse, such as bullying, severe neglect, or psychological trauma during childhood.
- Symptoms of obsessive-compulsive disorder can appear for the first time after a head injury.
- Personality traits: The risk of obsessive-compulsive disorder increases with some types of personalities that are characterized by perfectionism or an excessive sense of responsibility.
- Streptococcal infection: One of the causes of obsessive-compulsive disorder in children is streptococcal infection that causes or scarlet fever. This infection may lead to the appearance of obsessive-compulsive symptoms in some children suddenly, as the infection stimulates the immune system to produce antibodies that attack certain parts of the brain, while It is known as the Streptococcal-associated neuropsychiatric autoimmune disorder syndrome in children (in English: PANDAS Syndrome).
Obsessive-compulsive disorder may be associated with some other mental disorders, such as: 
- social anxiety disorder
- Eating disorders.
- Attention deficit hyperactivity disorder.
- Tourette’s syndrome.
It should be noted that the incidence of one of these conditions does not necessarily mean the occurrence of obsessive-compulsive disorder.