Obsessive-compulsive disorder (OCD) is a chronic, debilitating mental health condition characterized by distressing, intrusive obsessive thoughts and repetitive, compulsive physical or mental acts. OCD is a distinct condition but falls within the category of "obsessive-compulsive and related disorders," which includes:
- Obsessive-compulsive disorder (OCD)
- Body dysmorphic disorder
- Hoarding disorder
- Body-focused repetitive behaviors such as hair-pulling disorder (trichotillomania) and skin-picking disorder (excoriation)
- Substance/medication-induced obsessive-compulsive and related disorder
- Obsessive-compulsive and related disorder due to another medical condition
- Other specified and unspecified obsessive-compulsive and related disorders (e.g. body-focused repetitive behavior disorder, obsessional jealousy).
Hoarding disorder and excoriation were newly added to this category of disorders in the DSM-5, the Diagnostic and Statistical Manual used by clinicians and researchers to diagnose and classify mental disorders, which was published by The American Psychiatric Association (APA) in 2013.
OCD includes the following two characteristics: obsessions (undesirable, recurrent, intrusive, distressing thoughts and worries) and compulsions (repetitive or ritualized physical or mental behaviors). OCD is a chronic and debilitating mental health condition that is relatively common in both children and adults, is associated with a wide range of functional impairments and has significant social and occupational liabilities.1
Contents of this article:
You will also see introductions at the end of some sections to any recent developments that have been covered by MNT's news stories. Also look out for links to information about related conditions.
Fast facts on obsessive-compulsive disorder
- Obsessive-compulsive disorder (OCD) is characterized by distressing, intrusive obsessive thoughts and repetitive, compulsive physical or mental acts.
- Common obsessions include contamination, losing control, perfectionism, harm, unwanted sexual thoughts and religious obsessions.
- Common compulsions include washing and cleaning, checking, repeating and mental compulsions.
- The lifetime prevalence of OCD in the US is 2.3% and 12-month prevalence is 1.2%.2
- OCD occurs roughly equally in men and women and affects people of all races and socioeconomic backgrounds.3
- The first symptoms of OCD often begin during childhood or adolescence, however, the median age of onset is 19.4
- OCD could be triggered by a combination of genetic, neurological, behavioral, cognitive and environmental factors.
- Some people suffering OCD successfully hide their symptoms in fear of embarrassment or stigma.
- Treatment of OCD usually comprises of a combination of cognitive behavioral therapy (CBT) and selective serotonin reuptake inhibitors (SSRI).
- Research has shown that 75% of people with OCD are significantly helped by CBT.17
What is obsessive-compulsive disorder?
Obsessive-compulsive disorder (OCD) has a lifetime prevalence rate of 2.3% and manifests in compulsive urges to perform irrational or excessive avoidance behaviors.
According to a 2001 World Health Organization (WHO) mental health report, it is estimated that, in the year 2000, OCD was among the top 20 causes of illness-related disability worldwide for people aged 15-44, and that OCD was the fourth most common mental illness after phobias, substance abuse, and major depression.
OCD that begins in childhood is more common in boys than girls, with the usual time of onset of OCD later for females than males; the disorder is equally common among adult men and women.25
The presence of obsessions or compulsions or often both, distinguish obsessive-compulsive disorder. The obsessions or compulsions cause marked distress, are time-consuming and interfere with a person's normal functioning.
Causes of OCD?
Constant hand-washing and washing and cleaning in a specific way are common OCD compulsions.
Despite abundant research being carried out into obsessive-compulsive disorder, the exact cause has not been identified. OCD is, however, considered to have a neurobiological basis, with neuroimaging research showing that the brain functions differently in people with the disorder.
Abnormalities, or an imbalance in the neurotransmitters, or brain chemicals, including serotonin, dopamine or glutamine are thought to be involved in OCD.
In certain individuals, OCD could be triggered by a combination of genetic, neurological, behavioral, cognitive and environmental factors.
Genetic causes of OCD
Studies have shown that OCD runs in families and can be considered a "familial disorder."7 The disease may span generations with close relatives of people with OCD significantly more likely to develop OCD themselves.
Twin studies of adults suggest that obsessive-compulsive symptoms are moderately heritable, with genetic factors contributing 27-47% of variance in scores on measures of obsessive-compulsive symptoms.8-10 In studies of obsessive-compulsive symptoms in children, genetic factors account for 45-65% of variance.10
Although research indicates that genetic factors may contribute to OCD, no one gene has been identified as the "cause" of OCD. Two genes, SLC1A1 (the neuronal glutamate transporter gene) and hSERT (the serotonin transporter gene), have been proposed as factors in the development of OCD.
hSERT - human serotonin transporter gene
Abnormalities in serotonin regulation have been observed in people with OCD, as have mutations in hSERT, the human serotonin transporter gene. This gene contains the instructions for making serotonin transporters. These transporters soak up the surplus serotonin that remains after transmission of a nerve signal toward the next nerve cell in line.
In some people with OCD, a variant of the hSERT gene has been seen to encode for rapid uptake of serotonin, meaning that all the serotonin may be taken up by the transporters before the next nerve has heard the signal.
A study funded by the National Institutes of Health (NIH) examined DNA and found that OCD and certain related psychiatric disorders may be associated with an uncommon mutation of the human serotonin transporter gene (hSERT). They also discovered a second variation in the gene in some people with severe OCD symptoms. The mutations were as follows: 17
- I425V - a mutation of hSERT that increases transport activity, capturing more serotonin and most likely reducing effects at the receiving neuron's receptors.
- Two long alleles of the 5-HTTLPR polymorphism - a variant associated with increased expression and function of the serotonin transporter resulting in similar cellular effects to the I425V mutation: an increase in transporter proteins leading to less serotonin being available for neuronal communication.
When both mutations are present, there is significantly less serotonin available within the synapse than when either mutation occurs alone, resulting in greater biochemical effects and more severe symptoms.
SLC1A1 - glutamate transporter gene
Scientists have identified another gene called SLC1A1 that might be involved with OCD. This gene is similar to hSERT but has the job of encoding the neuronal glutamate transporter EAAC1, which soaks up the neurotransmitter glutamate (the excitotoxin formed in neurons form glutamine).17
Mutations in this gene may decrease glutamate uptake, leading to persistent excitation of neurons in people with OCD. However, some studies have shown mutations of SLC1A1 in people with OCD which appear to increase uptake of glutamate, indicating a need for further research.28
Some rapid onset cases of obsessive-compulsive disorder in children might be a consequence of Group A streptococcal infections, which cause inflammation and dysfunction in the basal ganglia.
These cases became grouped together as a set of clinical conditions referred to as pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS).11
In recent years, however, other pathogens, such as the bacteria responsible for Lyme disease, and H1N1 (the flu virus), have also been associated with rapid onset of OCD in children. As such, clinicians have altered the acronym to PANS - Pediatric Acute-Onset Neuropsychiatric Syndrome.
A paper published in 2014 in the journal Medical Hypotheses, proposed that episodic OCD is explained not by streptococcal infections but rather by alterations in gut microbiota resulting from the use of prophylactic antibiotics as treatment for the infections.
Given the increasing evidence of a relationship between gut microbiota and cognition, this is an interesting avenue for further research, with the possibility of a beneficial effect from concomitant treatment with probiotics and antibiotics.12,13
Neurological causes of OCD
Brain imaging techniques have allowed researchers to study the activity of specific areas of the brain, leading to the discovery that some parts of the brain are different in OCD sufferers compared with non-sufferers. Despite this revelation, it is not known exactly how these differences relate to the development of OCD.
Key areas of the brain that have demonstrated unusual activity in sufferers that may be involved in the development of symptoms of OCD include the:14,15
- Orbitofrontal cortex
- Anterior cingulate cortex
- Anterior cingulate gyrus
- Caudate nucleus
- Basal ganglia.
The circuit between the above areas regulates primitive aspects of behavior such as aggression, sexuality and bodily excretions. When activated, the circuit causes an urge to come to a person's attention and cause a particular appropriate behavior, such as hand-washing after visiting the bathroom. After this behavior, the urge diminishes, so, for example, the person will stop washing hands and move on to something else.
Brain scans have shown abnormal activity in patients with OCD.
Experts suggest that in people with OCD, the brain has difficulty turning off and ignoring urges from the circuit, which creates communication problems in these brain areas; the obsessions and compulsions continue, leading to repetition of the behavior, such as continual hand-washing.
The specific nature of this problem is unclear, but likely involves the chemicals in the brain such as serotonin, dopamine and glutamate.
The brain is a very complex structure. It contains billions of nerve cells, called neurons and it is essential they communicate and cooperate for the body to function normally. Neurons communicate via electrical signals. Special chemicals, called neurotransmitters, assist in moving these electrical messages from neuron to neuron.
There is a possible link between low levels or imbalance of the neurotransmitter serotonin and the development of OCD. Abnormalities in serotonin can affect brain pathways that connect areas dealing with judgment and planning to an area of the brain that filters messages involving body movements.
Abnormalities in the glutamatergic system have also been associated with neuropsychiatric conditions including OCD, autism and schizophrenia, with increased levels of glutamate seen in the cerebrospinal fluid of some people with OCD.28
Conversely, decreased levels of glutamate have been observed in some areas of the brain in pediatric and adult patients with OCD, suggesting that the link, if any, between glutamate and OCD is not one-directional.28
Behavioral causes of OCD
The behavioral theory suggests people with OCD associate certain objects or situations with fear and learn to avoid those things that trigger fear or learn to perform "rituals" in order to help reduce the fear.23
This fear and avoidance/ritual cycle may begin during a period of intense stress, such as when starting a new job or when a relationship comes to an end.
Once the connection between and object and the feeling of fear becomes established, people with OCD begin to avoid that object and the fear it generates, rather than confronting or tolerating the fear.
For example, a person who has always been able to use a public restroom may, when under stress, make a connection between the toilet seat and a fear of catching an illness. This person may begin to avoid using public restrooms or, if forced to use a public restroom, will perform elaborate cleaning rituals, such as cleaning the seat, door handles or following a detailed washing procedure.
These actions can offer temporary relief from the feeling of fear, but because the source of fear is never challenged or dealt with the behavior is reinforced over time. The fear associated with a specific object or situation may spread to similar objects such as public sinks and showers.
Cognitive causes of OCD23
The behavioral theory outlined above focuses on how people with OCD make an association between an object and fear, whereas, the cognitive theory focuses on how people with OCD misinterpret their thoughts.
Most people have unwelcome or intrusive thoughts at some time or other, but for those with OCD the importance of those thoughts are exaggerated.
For example, a person who is caring for an infant and who is under intense pressure may have an intrusive thought of harming the infant. Most people can shrug off and disregard the thought, but a person suffering from OCD may exaggerate the importance of the thought and respond as though it signifies a threat.
In the mind of the sufferer, a fleeting thought is changed to a dangerous intention, believing that they may be a threat to the child, which causes anxiety and negative emotion such as disgust, guilt and shame.
OCD sufferers who fear their own thoughts attempt to neutralize negative feelings that arise from their thoughts by avoiding the situations that trigger the thoughts or engaging in rituals such as excessively self-cleaning or praying.
As long as the sufferer interprets these intrusive thoughts as cataclysmic and true, they will continue the avoidance and ritual behaviors.
An international group of researchers known as the Obsessive-Compulsive Cognitions Working Group has suggested that people with OCD who attach exaggerated importance to intrusive thoughts may have developed false beliefs earlier in life. They list six types of dysfunctional beliefs that may lead to the development and maintenance of OCD including:
- Exaggerated responsibility - believing that one is solely responsible for preventing negative outcomes
- Exaggerated importance of thoughts - believing that having certain thoughts increases the probability of a negative event occurring, and (in the case of thoughts about actions) is morally equivalent to actually carrying out an action
- Control of thoughts - believing that it is essential and possible to have control over one's thoughts
- Exaggerated danger limitation - tending to overestimate the likelihood of danger and to believe that negative events will be particularly bad
- Exaggerated perfectionism - believing that everything should be perfect and that mistakes are unacceptable
- Intolerance of uncertainty - believing that one is able to and must know, without any doubt, that negative events will not occur.
Environmental causes of OCD
Environmental stressors may be a trigger for OCD in people with a tendency toward developing the condition. Twin studies suggest that obsessive-compulsive behaviors are largely attributable to genetic factors (accounting for some 59-80%) of persistent obsessive-compulsive behaviors.29
As such, environmental factors may contribute 20-41%, although some studies put the influence of environmental factors at 53-73% of variance in scores on measures of obsessive-compulsive symptoms.8-10
Traumatic brain injury (TBI) in adolescents and children has also been associated with an increased risk of onset of obsessive-compulsions, with one study finding that 30% of children aged 6-18 who experienced a TBI developed symptoms of OCD within twelve months of the injury.30
Overall, studies indicate that patients with OCD frequently report stressful and traumatic life events before the illness begins.6 These events may also exacerbate symptoms. Possible environmental factors include:
- Changes in living situation
- Death of a family member or friend
- Changes or problems in school or work
- Relationship worries.
Recent developments on OCD causes from MNT news
Characterized by persistent thoughts or urges, obsessive-compulsive disorder forces individuals to perform repetitive actions to try to relieve anxiety about their uncontrollable thoughts. Dogs can also suffer from this disorder and researchers say they may be able to serve as a simplified model of the human condition, after finding certain genetic links.
An investigation of the brain circuits behind compulsive behavior has revealed a surprisingly intimate connection with the circuits that control obesity. The researchers say the discovery offers new insights into the development and treatment of both compulsive behavior and eating disorders.
The cause or causes of obsessive-compulsive disorder remain unknown, but researchers from Johns Hopkins University School of Medicine in Baltimore, MD, say they have uncovered a genetic marker that may provide clues.
Researchers from the University of Cambridge in the UK say compulsions from OCD may originate from misfiring of the brain's control system. Their research has been published in the American Journal of Psychiatry.
Living with OCD
This YouTube video, by The Mighty Site, is a 3 minute video diary of one sufferer of OCD, giving a glimpse of what it is like living with OCD.
On the next page, we look at the common symptoms of OCD, some of the common obsessions and how OCD can be diagnosed. On the final page we discuss treatments for OCD, including CBT and cognitive therapy.