OCD

• OCD (obsessive compulsive disorder) is a long lasting disorder in which the patient experiences uncontrollable and recurring thoughts (obsessions) and repetitive behaviours (compulsions).
• Behavioural characteristics of OCD:

  • Compulsions - Behaviours are repeated to reduce anxiety, but the reduction is only temporary.

  Examples of this are checking behaviour (eg testing to see if the door is locked) and ritual cleaning behaviours (eg repeatedly washing hands).
• Behavioural characteristics of OCD:

  • Avoidance - Negatively reinforced behaviour to avoid an encounter with a specific trigger to obsessions.
• Behavioural characteristics of OCD:

  • Social impairment - Not participating in social events due to difficulty leaving the house without triggering the obsessions / need to carry out compulsions become time-consuming.
• Emotional characteristics of OCD:

  • Anxiety - Uncomfortably high and persistent state of arousal making it difficult to relax. This is a result of the constant 'worst case scenario' thinking that occurs in patients with OCD.
• Emotional characteristics of OCD:

  • Depression - Consistent and long-lasting sense of sadness resulting from being unable to control the anxiety causing thoughts and the OCD symptoms taking over the sufferers life.
• Cognitive characteristics of OCD:

  • Obsessive thoughts - Repetitive focus on the stimulus causing an excessive amount of anxiety leading to compulsive behaviours.
• Cognitive characteristics of OCD:

  • Hypervigilance - Permeant state of awareness where the patient is looking for the source of the obsessive thoughts (eg thinking of the potential threat of germs).
• Cognitive characteristics of OCD:

  • Selective attention - Patient is very focused on the objects connected to OCD that they find it hard to maintain conversations with others.
• Biological approach to explaining OCD:

  • Behaviour is a result of our genetics and physiology, which varies from person to person.
• Biological approach to explaining OCD:

  • Lewis et al (1936) - Genetic explanation for OCD.

  Diathesis-Stress model suggests some people are more vulnerable to developing OCD through a trigger.

  • He found 37% of patients had parents with OCD, and 21% had siblings with OCD.
• Biological approach to explaining OCD - Genetic explanations:

  • Taylor (2013) - Polygenic

  There are up to 230 different genes involved in the development of OCD. These are known as candidate genes.

  • SERT gene (5H1D-beta) - Implications in the transport of serotonin across synapses, affecting the reuptake.
  • COMT gene - Responsible for clearing dopamine from synapses.

  OCD is aetiologically heterogenous, meaning that its origin may have many different causes. For example - Hoarding disorder is caused by a particular variation of genes.
• Biological approach to explaining OCD:

  • Neural explanations - Biochemical imbalance of neurotransmitters in the brain.
• Biological approach to explaining OCD - Neural explanations:

  • Serotonin

  Low levels of serotonin is due to it being removed too quickly, not allowing the signal to be transmitted to the postsynaptic neurone. This results in the obsessive thoughts in OCD patients.

  
  

  Presynaptic neurone releases the neurotransmitters which diffuse across the synaptic cleft and bind to a receptor site. If the signal is strong enough, it is passed on to the postsynaptic neurone. The neurotransmitter is then detached from the receptor site and travels back to the presynaptic membrane to be used again - reuptake.
• Biological approach to explaining OCD - Neural explanations:

  The worry circuit:

  • Normal functioning = Basal ganglia filters out small worries from the OFC.
  • OCD patient = ^ This area of the brain is hyperactive so small worries are sent to the thalamus and passed back to the OFC (recurring loop of obsessive thoughts).

  Repetitive motor functions (compulsions) attempt to break this loop. While carrying out the compulsion there is temporary relief, until the hyperactive basal ganglia resumes the worry circuit again.
• Strengths of the biological approach to explaining OCD:

  • Supporting evidence - Nestadt et al (2010) reviewed previous twin studies and found high concordance rates between close family members and OCD;

  68% of MZ twins compared to 31% of DZ twins shared OCD, suggesting there is a genetic basis for these genes (MZ twins share 100% of their genes while DZ only share 50%)
• Strengths of the biological approach to explaining OCD:

  • Supporting evidence from neuroimaging - Several PET scanners have shown hyperactivity in the OFC and the caudate nucleus of patients, both when at rest and when stimulated. However, researchers can not be sure if this is the cause of OCD or the consequence of having OCD.
• Limitations of the biological approach to explaining OCD:

  • Alternative explanations - The Diathesis-Stress model may be a more valid explanation than biological factors alone. Individuals inherit genetic vulnerability to the disorder (diathesis), but the disorder does not develop until there is an environmental factor (stressor).

  Cromer showed 54% of 265 patients with OCD reported a traumatic event in their life, and those with multiple reported more severe symptoms.
• Limitations of the biological approach to explaining OCD:

  • Reductionist explanation - Ignores all other factors which may contribute to the development of the disorder. For example, it does not take into account the cognitive and learning aspects; some psychologists argue OCD may be classically conditioned and maintained through operant conditioning (dirt is associated with anxiety, and this is operantly conditioned through the practice of washing hands to reduce the anxiety).
• Biological approach to treating OCD:

  • Drug therapy - Selective serotonin reuptake inhibitors (SSRI's)

  Antidepressant drugs, such as Fluoxetine (aka Prozac), are used to control the symptoms of OCD.

  SSRI's influence select serotonin in the brain as reuptake inhibitors (slowing down the reuptake process in the synapse). This decreases anxiety by normalising the activity of the worry circuit.
• Biological approach to treating OCD - Drug therapy:

  When an SSRI is not effective after 3-4 months, alternatives may be used;

  • Tricyclics (an older type of antidepressants) - Clomipramine is a type of Selective noradrenaline reuptake inhibitor (SNRI) and they increase the concentration of noradrenaline neurotransmitter in the brain.

  However, these have more severe side effects and so are generally reserved for patients who do not respond to SSRIs.
• Strengths of the biological approach to treating OCD:

  • Economic benefits - Increased knowledge about the effectiveness of certain drug treatments for OCD and cognitive treatments can reduce the time people take off work for sick days, thus increasing productivity in the workforce. As a result, more people would be paying taxes which can help the NHS save money by choosing the most effective treatments to use.
• Strengths of the biological approach to treating depression:

  • Supporting evidence - Soomro et al (2009) conducted a meta analysis combining the data from 17 studies that compared SSRIs to placebos (3097 participants). The results showed that SSRIs significantly reduced the symptoms of OCD compared to placebos between 6 and 17 weeks post treatment, suggesting that drug therapy is effective.
• Limitations of the biological approach to treating OCD:

  • Side effects - More than 1/10 patients taking Clomipramine suffered from erectile dysfunction, weight gain and tremors. More than 1/100 suffered increased heart rate and aggressiveness. These can have serious impacts on how the patient can go about their everyday life.