OCD (obsessive compulsive disorder) (Key terms (OCD (obsessive compulsive…
OCD (obsessive compulsive disorder)
Compulsive behaviours reuce anxiety caused by obsessive thoughts. They may be overt, such as hand washing, or covert, such as prayer to avert perceived danger. Failure to carry out the behaviour leads to excessive anxiety. Some compulsions are not preceded by obsessive thoughts.
OCD can cause anxiety and distress, embarrassment and shame.
Obsessions are recurrent, intrusive and unwelcome thoughts which the individual will, at some point, recognise as excessive and unreasonable.
The biological approach to explainig OCD
The COMT gene
The COMT gene produces the enzyme, which regulates the production of dopamine, a neurotransmitter implicated in OCD. One COMT gene variation more common in OCD patients results in lower activity of the COMT gene and higher levels of dopamine (Tukel et al. 2013).
The SERT gene
The SERT gene affects the transport of serotonin also implicated in OCD, lowering levels of this neurotransmitter. Ozaki et al. (2003) found a mutation of this gene in 2 unrelated families where 6 of the 7 family members had OCD.
Individual genes may create a vulnerability (a diathesis) for OCD, which is only expressed if particualr stressors are present. Some people could possess gene variations but suffer no stressors and, therefore, no ill effects.
Abnormal levels of neurotransmitters
Dopamine levels may be abnormally high in people with OCD since dopamine-enhancing drugs induce stereotyped movements resembling compulsive behaviours of OCD in animals (Szechtman et al, 1998). Lower serotonin levels are associated with OCD: antidepressant drugs that increase serotonin can reduce OCD symtoms (Pigott et al., 1990).
Abnormal brain circuits
Several areas in the frontal lobes of the brain are thought to be abnormal in people with OCD e.g. the orbitofrontal cortex (OFC) sends worry signals to the thalamus. These are normally suppressed by the caudate nucleus but if this is damaged, the thalamus is alerted and confirms the worry to the OFC creating a worry circuit.
Family and twin studies
Compared tot he general poulation, people with a first-degree relative with OCD have a 5x greater risk of having the illness at some time (Nestadt et al., 2000). Compared to non-identical twins, indentical twins are more likely than 2x as likely to develop OCD if their co-twin has it (Billettet al., 1998). Concordance rates are never 100%, so environmental factors must contribute.
Research support for genes and OFC
Many studies demonstrate the genetic link to abnormal levels of neurotransmitters. Compared to unrelated healthy people, OCD patients and their close relatives had reduced grey matter in key regions of the brain including the OFC (menzies et al., 2007). Anatomical differences are inherited and these may lead to OCD in certain individuals.
Tourette's syndrome and other disorders
Genes may merely predispose individuals towards obsessive-type behaviour. Pauls and Leckman (1986) argued that OCD is one expression of the same gene that determines Tourette's syndrome. OCD symptoms are also present in autism and anorexia nervosa, and two out of every three OCD patients also experience at least one episode of depression (Rasmussen and Eisen, 1992). There is, therefore, no one gene directly and exclusively responsible for OCD.
The biological approach to treating OCD
Low levels of the neurotransmitter serotonin are associated with depression as well as OCD so antidepressants are used to increase levels of serotonin in both disorders. They may normalise the 'worry circuit'. Antidepressants also reduce anxiety associated with OCD. Selective serotonin re-uptake inhibitors are currently the preferred drug for treating anxiety disorders. They increase levels of the serotonin thus regulating mood and anxiety.
The antidepressant tricyclic clomipramine is today primarily used in the treatment of OCD rather than depression. Tricyclics block the mechanism that re-absorbs both serotonin and noradrenaline, prolonging their activity. Tricyclics have the advantage of targeting more than one neurotransmitter, however they have greater side effects so are used as a second-line treatment for patients where SSRIs were not effective.
Benzodiazepines are commonly used to reduce anxiety. BZs slow down the activity of the central nervous system by enhancing the activity of the neurotransmitter GABA. This is the neurotransmitter that has a general quietening effect on many of the neurons in the brain by reacting with special sites on the outside of neurons.
Recent research has found that D-Cycloserine has an effect on reducing anxiety and thus may be an effective treatment for OCD, particularly when used in conjunction with psychotherapy. D-Cycloserine is an antibiotic used in the treatment of turberculosis. It also appears to enhance the transmission of GABA and thus reduce anxiety
Soomro et al. (2008) reviewed 17 studies of the use of SSRIs with OCD patients and found them to be more effective than placebos in reducing the symptoms of OCD up to three months after treatment. However, most studies are only of three or four months' duration and therefore little long-term data exists (Koran et al. 2007)
Drug therapies are preferred to other treatments
Drug therapy generally requires less time and effort than other therapies such as CBT. It is also relatively cheaper and requires less monitoring. Furthermore, some benefit may derive from simply talking with a doctor during consultations.
All drugs have side effects. Possible side effects of BZs include increased aggressiveness, long-term impairment of memory and possible addiction. Side effects may amount to costs that outweigh benefits and thus stop a patient taking a drug.
Not a lasting cure
In a review of treatments for OCD, Koran et al. (2007) suggested that, although drug therapy may be more commonly used, psychotherapies such as CBT should be tried first. Drug therapy may be efficient in the short term but it does not provide a lasting cure, as indicated by the fact that patients relapse within a few weeks if medication is stopped. (Mania et al., 2001)
OCD (obsessive compulsive disorder)
An anxiety disorder where anxiety arises from both obsessions and compulsions. Compulsions are a response to obsessions and are believed to reduce anxiety.
A measure of genetic similarity
A part of the chromosome of an organism that carries information in the form of DNA.
Chemical substances that play an important part in the workings of the nervous system by transmitting nerve impulses across a synapse.
GABA (gamma-aminobutyric acid)
A neurotransmitter that regulates excitement in the nervous system, thus acting as a natural form of anxiety reducer.