Biological explanation&treatment for OCD

• Biological explanations are divided into genetic explanations and neural explanations.
• • Genetic explanations suggest OCD is inherited and that individuals inherit specific genes which cause OCD​
  • The two candidate genes have been linked to OCD, including the COMT gene and SERT gene.
• The COMT gene 

  associated with the production of an enzyme called catechol-O-methyltransferase, which regulates dopamine. ​

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  One variation of the COMT gene results in higher levels of dopamine and this variation is more common in patients with OCD. 

  (Tukel et al)

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• The SERT gene (5-HTT gene) 

  affects the transport of the serotonin, causing lower levels of serotonin which is also associated with OCD. 

  (Ozaki et al).
• • Diathesis Stress:OCD is too complex for it to just be caused by one gene​
  • It is likely that each individual gene that is not working properly causes a vulnerability (A DIATHESIS) for OCD in a person and then other factors (STRESSORS - make feel patient worried,anxious) affect what condition develops.
• Neural explanations of OCD focuses on:​ neurotransmitters as well as brain structures.​
• Neural explanations suggest that 

  abnormal levels of neurotransmitters, in particular serotonin and dopamine, are implicated in OCD.
• Neural explanations also suggest that particular regions of the brain, in particular the basal ganglia and orbitofrontal cortex, are implicated in OCD.
• • Some cases of OCD are also associated with the reduced levels of serotonin. ​
  • Support comes the use of anti-depressants, drugs which increase the level of serotonin are effective in reducing symptoms OCD. (Pigott et al)​
  • Higher levels of dopamine being associated with compulsive behaviours.(Szechman et al)
• The basal ganglia is a brain structure:

  • involved in multiple processes, including the coordination of movement.
  • Patients who suffer head injuries in this region often develop OCD-like symptoms. ​

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  • Max et al. (1994) found that when the basal ganglia is disconnected from the frontal cortex during surgery, OCD-like symptoms are reduced, providing further support for the role of the basal ganglia in OCD.​
• The orbitofrontal cortex, a region which

  • converts sensory information into thoughts and actions. 
  • PET scans have found higher activity in the orbitofrontal cortex in patients with OCD. ​

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  • May be the heightened activity in the orbitofrontal cortex increases the conversion of sensory information to behaviours which results in compulsions. ​

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  • The increased activity also prevents patients from stopping their behaviours.​
• Twin studies: Provide strong evidence for a genetic link.

  • Nestadt et al. (2010) conducted a review of previous twin studies examining OCD. They found that 68% of identical twins and 31% of non-identical twins experience OCD, which suggests a very strong genetic component.​
  •  However, no twin study has found a concordance rate of 100% in identical twins:
  • biological factors are not the only factor contributing to OCD and there must be environmental factors which also contribute to this disorder.​
• Strength: Family studies.

  • Lewis (1936) examined patients with OCD and found that 37% of the patients with OCD had parents with the disorder and 21% had siblings who suffered. ​

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  • Research from family studies provide support for a genetic explanation to OCD, although it doesn’t rule out environmental factors playing a role.​
• Genes are not exclusive to one disorder​:

  • Pauls and Leckman (1986) - Tourette's syndrome patients.
  • They concluded that OCD is one form of expression of the same gene that causes Tourette's.​

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  • The obsessive behaviour is found in children with autism, who also display compulsions.​
  • Obsessive behaviour is also characteristic of anorexia nervosa. ​
  • 2 out of 3 people with OCD also experience at least 1 episode of depression​

  This all supports the view that there is not one specific gene or gene unique to OCD, they just act as a predisposing factor. ​
• Support for the neural explanations of OCD come from research examining biological treatments including anti-depressants:

  Anti-depressants typically work by increasing levels of the neurotransmitter serotonin. ​

  Effective in reducing the symptoms of OCD and provide support for a neural explanation of OCD.
• Issues and Debates:

  • One weakness - ignores other factors and is reductionist. ​
  • The biological approach does not take into account cognitions and learning. ​
  • Some psychologists suggest that OCD may be learnt through classical conditioning and maintained through operant conditioning stimulus is associated with anxiety and this association is then maintained through operant conditioning, where a person avoids dirt and continually washes their hands. ​
  • This hand washing reduces their anxiety and negatively reinforces their compulsions.​
• Biological treatments for OCD aim

  to restore biological imbalances, such as too little serotonin. 
• Drug treatments are based on the assumption that chemical imbalances are the main cause of the problem.
• Two types of drug are used for the treatment of OCD: ​

  •  anti-depressants 
  •  anti-anxiety drugs
• All Antidepressants - Affect levels of neurotransmitters including serotonin.
• Antidepressants: SSRIs

  Increase levels of serotonin at the synapse by blocking/ preventing reuptake. 
• Antidepressants: ​Tricyclics 

  block the transporter mechanism that re-absorbs both serotonin and noradrenaline into the presynaptic cell after it is fired. 

  Tricyclics target more than one neurotransmitter but have greater side effects than SSRI’s.​
• Anti-anxiety drugs: 

  work by slowing the activity of the Central Nervous system by enhancing the activity of the neurotransmitter GABA.
• Combination treatment :SSRIs combined with psychological therapies like CBT and with other drugs.​​
• Strength - comes from research support which uses randomised drug trials.  ​

  • These trials compare the effectiveness of SSRIs and placebos.​
  • Soomro et al. (2008) - the effectiveness of SSRIs and
  • Found that SSRIs were more effective than placebos in the treatment of OCD, in 17 different trials. ​
  • This supports the use of biological treatments, especially SSRIs, for OCD.​
• Strength of biological treatments is their cost.​

  • Anti-depressants and anti-anxiety drugs are relatively cost effective compared to (CBT). ​
  • Doctors often prefer to prescribe them, they are more economical for the NHS compared to CBT​
  • Drugs are more successful for patients who lack motivation to complete intensive CBT​, as they are taken until the symptoms subside.​
• Weakness - possible side effects of drugs like SSRIs and BZs. 

  • SSRIs - some patients experience mild side effects like indigestion, or more serious - hallucinations, erection problems and raised blood pressure. ​
  • BZs - highly addictive and can also cause increased aggression and long-term memory impairments. They are only prescribed short-term treatment.​
  • Side effect diminish the effectiveness of drug treatments, as patients will often stop taking medication due to the side effects.​
• Criticised for treating the symptoms of the disorder and not the cause:

  • SSRIs work by increasing the levels of serotonin in the brain, which reduces anxiety and alleviates the symptoms of OCD, BUT it does NOT treat the underlying cause of OCD. ​

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  • Once a patient stops taking the drug, they are prone to relapse, suggesting that psychological treatments may be more effective, as a long-term solution.​