OCD

• describe the genetic explanations for OCD

  • specific candidate genes which are implicated in OCD
  • COMT gene: associated with enzyme that is associated with regulating neurotransmitter dopamine
  • SERT gene: linked to serotonin and affects the transport of this neurotransmitter
• neurotransmitter explanation for OCD

  • serotonin: regulates mood
  • lower levels of serotonin are associated with mood disorders
  • dopamine: feelings of pleasure, satisfaction and motivation
  • higher levels of dopamine have been associated with some of the symptoms of OCD, in particular, the compulsive behaviours
• brain structure explanation for OCD

  • basal ganglia: involved in multiple processes, including the coordination of movement
  • orbitofrontal cortex: converts sensory information into thoughts and actions. heightened activity in the orbitofrontal cortex increase the conversion of sensory information to actions which results in compulsions
• strengths of biological approach to explaining OCD (1)

  • family studies: Lewis (1936) found that 37% of the patients with OCD had parents with the disorder and 21% had siblings who suffered. Nestadt et al. (2000) proposes that individuals who have a first‐degree relative with OCD are up to five times more likely to develop the disorder over their lifetime compared to members of the general population without this genetic link. Research from family studies like this provides support for a genetic explanation for OCD, although it does not rule out other (environmental) factors playing a role.
• strengths of biological approach to explaining OCD (2)

  • twin studies: Billett et al. (1998) conducted a meta‐analysis of 14 twin studies investigating the genetic inheritance rate of OCD. It was concluded that monozygotic (MZ) twins had double the risk of developing OCD compared to dizygotic twins (DZ) if one of the pair had the disorder. Since concordance rates in twin studies are never 100%, it suggests that the diathesis‐stress model may be a better explanation whereby a genetic vulnerability is inherited and triggered by a stressor in the environment.
• how do drug therapies treat OCD?

  • Selective Serotonin Reuptake Inhibitors (SSRIs) increase levels of serotonin in the synapse by preventing it from being absorbed into the pre-synaptic neurone
  • increases the level of serotonin in the synapse therefore more serotonin binds to complementary receptors on the post-synaptic neuron so the post-synaptic neurone is continually stimulated
• strengths of biological treatments of OCD (1)

  • research support for their effectiveness: Soomro et al. (2008) conducted a review of research examining the effectiveness of SSRIs and found that they were significantly more effective than placebos in the treatment of OCD, across 17 different trials. This supports the use of biological treatments, especially SSRIs, for OCD. However, studies such as this are criticised for only concluding the short‐term effectiveness of drug treatments with long‐term effects still to be investigated empirically.
• strengths of biological treatments of OCD (2)

  • Drug therapies are relatively cost‐effective in comparison with psychological treatments, like CBT. Many doctors prefer the use of drugs as they are a more cost‐effective solution for treating OCD, which is beneficial for economy. Psychological treatments like CBT require a patient to be motivated to engage whereas drugs are non‐disruptive to everyday life. As a result, this means that drug treatments are likely to be more successful for patients who lack the motivation to complete intense psychological treatments.
• limitations of biological treatments of OCD (1)

  • This explanation for OCD reduces a complex human behaviour to a single gene or brain chemical and so is considered biologically reductionist. For example, the biological explanation does not consider the role cognitions (thinking) or learning in the development or maintenance of OCD.
  • The biological explanation follows a nomothetic approach which suggests the same treatment for all people suffering from OCD, without considering individual differences.
• limitations of biological treatments of OCD (2)

  • Drug treatments are criticised for treating the symptoms of the disorder and not the cause. Although SSRIs work by increasing the levels of serotonin in the brain, which reduces anxiety and alleviates the symptoms of OCD, it does not treat the underlying cause of OCD. Furthermore, once a patient stops taking the drug, they are prone to relapse. Koran et al. (2007) suggest that psychological treatments such as CBT may be a more effective long‐term solution to provide a lasting treatment and a potential cure.