Introduction
Obsessive Compulsive Disorder_Disease Background
Obsessive-compulsive disorder is characterized by the presence of either obsessions or compulsions, but more commonly by both symptoms. An obsession is a repeated, intrusive, unwanted thought, image, or urge that causes distressing emotions (eg anxiety and disgust). Patients with obsessive-compulsive disorder attach to the occurrence and/or content of the intrusions. They tend to believe that these urges or thoughts are immoral or dangerous and that they can prevent harm to themselves or another person. Compulsion is a repetitive behavior or mental act that the person feels driven to perform in order to lessen the distress caused by the obsession. It aims to reduce harm or make the patient feel comfortable. Anxiety is a central feature of obsessive-compulsive disorder.
Epidemiology
There is a 1.1-1.8% prevalence of obsessive-compulsive disorder worldwide. In China, about 2.4% of people experience obsessive-compulsive disorder in their lifetime, which is almost identical to the 2.3% rate in the United States. Other countries show slightly higher numbers, with lifetime rates reaching 3.0% in Singapore and 3.8% in Australia. Over any given 12-month period, about 1% to 3% of the population actively struggles with the condition globally, including a 3.0% rate found in Turkey.
Individuals between the ages of 18 and 29 are the demographic group most frequently affected. During adulthood, there is a slightly higher prevalence in women, but in childhood, men are the ones commonly affected.
Pathophysiology
Obsessive-compulsive disorder cases can be directly linked to neurological issues in the brain's basal ganglia. Some studies showed that obsessive-compulsive disorder is driven by dysfunctions in the brain's cortico-striato-thalamo-cortical circuit, as well as imbalances in key neurotransmitters like serotonin, dopamine, and glutamate. Postmortem tissue studies reveal structural abnormalities in the orbitofrontal cortex of individuals with obsessive-compulsive disorder. This has a lower expression of excitatory synaptic genes compared to healthy controls.
Risk Factors
Obsessive-compulsive disorder behaviors can be triggered by central nervous system infections, head injuries, or related neurological conditions (eg Tourette syndrome, epilepsy).