Biological Therapies for OCD Flashcards
Explain Drugs as a therapy
Biological therapies arise from the medical model of abnormal behaviour. According to this model, metal disorder is an illness which results mainly from a chemical imbalance. Biological treatments aim to redress the balance by direct physiological treatments - drugs, ETC and psychosurgery.
As a GP is usually the first practitioner to treat a person with OCD, drug therapy is the most usual form of therapy.
There are a number of different drugs that are prescribed for OCD. Antidepressants are the most commonly prescribed drug. They are used to reduce the anxiety associated with OCD. There are 2 types of antidepressants prescribed for OCD - tricyclics (increase the availability of noradrenaline and serotonin) and SSRI’s (increase the availability of serotonin). Low levels of serotonin in the ‘worry circuit’ (OFC, Caudate nuclei and thalamus) offers an explanation for OCD. Increasing levels of serotonin may therefore normalise this circuit and offers an explanation for how antidepressants may be effective in reducing OCD symptoms.
Discuss Tricyclics
Clomipramine was the first antidepressant used for OCD and today is primarily used for OCD rather than depression. Tricyclics block the transporter mechanism that reabsorbs both serotonin and noradrenaline into the presynaptic cell after it has fired. As a result more of these neurotransmitters are left in the synapse prolonging activity and easing transmission of the next impulse.
Discuss SSRI’s
For example Prozac.
these block the re-uptake of serotonin and so increase the quantity available to excite/inhibit neighbouring brain cells, reducing the symptoms of anxiety.
Discuss anti-anxiety drugs - benzodiazepines
BZ’s slow down the activity of the CNS by enhancing the activity of GABA. GABA is a neurotransmitter that has a quietening effect on many of the neurons in the brain. GABA locks onto the receptor sites outside the neuron. This opens a channel which allows chloride ions to flow in to the neuron. Chloride ions make it harder for the neuron to be stimulated by other neurotransmitters, thus slowing down its activity and making the person feel more relaxed.
Evaluate drug therapy in terms of effectiveness
There is considerable evidence for the effectiveness of SSRI’s for the treatment of OCD. For example, Somoro et al - reviewed 17 studies of the use of SSRIs with OCD and found them to be more effective than placebo in reducing the symptoms of OCD as measured with Y-BOCS up to 3 months after treatment i.e. in the short term. However, it has been suggested that 30-50% of clients with OCD derive no benefit from them, so they are not effective for a large minority. Furthermore relapse rates are thought to be as high as 90%. Therefore drugs do not provide a permanent ‘cure’ for the disorder as soon after treatment stops, symptoms return. This suggests psychological therapies are more effective as they provide the client with active strategies for dealing with the disorder, rather than them taking a passive role as in drug therapy. Relapse rates are much lower when drugs are combined with ERP (simpson et al).
The tricyclic clomipramine, is often regarded as more effective than SSRIs (Koran et al). However, tricyclics tend to have more unpleasant side effects (e.g. dry mouth, memory problems and blurred vision). Foa and Kozak stated that between 50 to 60% of sufferers will benefit from clomipramine. However, this doesn’t take into account people who drop out of the studies due to the side effects thus producing skewed results.
Evaluate drug therapy in terms of appropriateness
There are reasons for arguing that drug therapy for OCD is appropriate and justifiable. Firstly, they reduce anxiety and symptoms of OCD in many patients and it is appropriate in view of the increasing evidence that OCD is associated with complex abnormalities of serotonin and dopamine function. In other words, part of the problem in OCD is biochemical and drug therapy is thus appropriate as a treatment that produces biochemical changes. Moreno - however states that there is no consensus view on the function of serotonin and other neurotransmitters in the cause of OCD and therefore, drugs which increase these chemicals should be avoided when treating this disorder.
Koran et al - suggests psychotherapy should be tried first as it does not provided a lasting cure as indicated by the high relapse rates once medication stops.
Side effects can be very unpleasant, therefore this treatment may be inappropriate for some. This treatment is based on the biological approach which may be seen as deterministic and can dehumanise patients by taking away any sense of personal responsibility or control.
Explain psychosurgery
Psychosurgery is brain surgery to change behaviour. It is a very rare treatment today and is only used as a last resort for treating OCD when all other treatment options have failed. Psychosurgery involves destroying a small amount of brain tissue in the areas of the brain believed to be involved in OCD, in this case the corticostriatal circuit involving the orbito-frontal cortex, the caudate nucleus, the thalamus and the anterior cingulated cortex. This is done by inserting a probe through the skull into the cingulated gyrus (a bunle of connections that regulate the circuit that is hyperactive in OCD). The probes’ tips are the heated and tissue is burned. This is known as a cingulotomy. Other techniques involve a capsulotomy and limbic leucotomy.
Evaluate psychosurgery in terms of effectiveness
Baer et al - reported that cingulotomy was successful in decreasing anxiety and OCD behaviour. More recently, however, Cosgrove - found that the procedure produced marked benefits in only 30% patients. The evidence about the effectiveness of psychosurgery, therefore, is inconsistent, although it has been estimated that long-term effectiveness is alleviating symptoms is somewhere between 25-70%. However this technique is drastic and irreversible and can cause seizures and other side effects.
Evaluate psychosurgery in terms of appropriateness
Psychosurgery also raises ethical issues about informed consent: patients who are disturbed enough to warrant consideration for psychosurgery might well not have the insight to understand the implications of such therapies. It is a very expensive treatment using potentially dangerous invasive surgery.
Explain psychosurgery
Psychosurgery is brain surgery to change behaviour. It is a very rare treatment today and is only used as a last resort for treating OCD when all other treatment options have failed. Psychosurgery involves destroying a small amount of brain tissue in the areas of the brain believed to be involved in OCD, in this case the corticostriatal circuit involving the orbito-frontal cortex, the caudate nucleus, the thalamus and the anterior cingulated cortex. This is done by inserting a probe through the skull into the cingulated gyrus (a bunle of connections that regulate the circuit that is hyperactive in OCD). The probes’ tips are the heated and tissue is burned. This is known as a cingulotomy. Other techniques involve a capsulotomy and limbic leucotomy.
Evaluate psychosurgery in terms of effectiveness
Baer et al - reported that cingulotomy was successful in decreasing anxiety and OCD behaviour. More recently, however, Cosgrove - found that the procedure produced marked benefits in only 30% patients. The evidence about the effectiveness of psychosurgery, therefore, is inconsistent, although it has been estimated that long-term effectiveness is alleviating symptoms is somewhere between 25-70%. However this technique is drastic and irreversible and can cause seizures and other side effects.
Evaluate psychosurgery in terms of appropriateness
Psychosurgery also raises ethical issues about informed consent: patients who are disturbed enough to warrant consideration for psychosurgery might well not have the insight to understand the implications of such therapies. It is a very expensive treatment using potentially dangerous invasive surgery.
