The biological approach to explaining and treating OCD:

• Candidate genes

  Specific genes that are believed to increase the risk of developing OCD. These genes are often linked to the regulation of neurotransmitters, particularly serotonin and dopamine, which are involved in mood and behaviour.
• Polygenic

  Polygenic refers to the idea that OCD (and other disorders) is influenced by multiple genes, rather than a single gene. These genes, each contributing a small effect, work together to increase the risk of developing OCD. Research suggests that there may be up to 230 different genes involved in OCD and that different genetic variations contribute to different types of OCD.
• Biological approach

  A perspective that emphasises the importance of physical processes in the body, such genetic inheritance and the neural function.
• Genetic explanations

  Genes are involved in individual vulnerability to OCD. Lewis (1936) observed that of his OCD patients. 37% had parents with OCD, and 21% had siblings with OCD. This suggests that OCD runs in families, although what is probably passed on from one generation to the next is genetic vulnerability, not the certainty of OCD.
• Diathesis-stress model

  The diathesis-stress model explains OCD as the result of a genetic vulnerability combined with a stressor (such as a stressful life event), which together trigger the disorder.
• COMT gene

  A gene linked to the regulation of dopamine. A variation of the COMT gene may lead to higher dopamine levels, which is associated with increased OCD symptoms, particularly compulsive behaviours.
• SERT gene

  The SERT gene is linked to serotonin and affects the transport of this neurotransmitter. The transportation issues cause lower levels of serotonin in the brain which is associated with OCD and depression.
• The role of serotonin

  Serotonin is believed to help regulate mood. If a person has low levels of serotonin, normal transmission of mood-relevant information does not take place, which may affect mental processes and lead to OCD symptoms.
• Decision making systems

  OCD is linked to abnormal functioning in the lateral frontal lobes, especially the orbitofrontal cortex (OFC), which is involved in decision-making. The caudate nucleus (part of the basal ganglia) may fail to suppress intrusive thoughts from the OFC. The parahippocampal gyrus, associated with processing unpleasant emotions, also shows abnormal activity in people with OCD.
• What happens when the basal ganglia is damaged due to a head injury?

  The basal ganglia is a cluster of neurons at the base of the forebrain. Damage to this area, can lead to OCD-like symptoms, such as compulsive behaviors and repetitive thoughts.
• Strength of G.E for OCD - Research support

  A major strength is its strong evidence base. Nestadt et al. (2010) reviewed twin studies and found that 68% of identical twins both had OCD, compared to 31% of non-identical twins. This significant difference suggests that genetic factors play a key role in OCD, strongly supporting the biological explanation.
• Limitation of G.E for OCD - Environmental risk factors

  Not all OCD cases are caused by genes — environmental factors also play a role. For example, Cromer et al. (2007) found that over half of OCD patients had experienced a traumatic life event, and those with more than one trauma had more severe symptoms. This suggests that OCD is not purely genetic and may be better explained by a diathesis-stress model.
• Strength of N.E for OCD - Research support

  A strength is strong research support from studies showing brain and neurotransmitter abnormalities in OCD. For example, brain scans have found that people with OCD often have increased activity in the orbitofrontal cortex, a region linked to decision-making and compulsions. This supports the idea that abnormal brain function is involved in OCD.
• Drug therapy

  Treatment involving drugs, i.e., chemicals that have a particular effect on the functioning of the brain or some other body system. In the case of psychological disorders, such drugs usually affect neurotransmitter levels.
• SSRIs

  SSRIs (Selective Serotonin Reuptake Inhibitors) treat OCD by increasing serotonin levels in the brain. They work by blocking the reabsorption (reuptake) of serotonin, making more serotonin available to improve mood and reduce symptoms of obsessions and compulsions.
• How do SSRIs affect synaptic transmission in the brain?

  • Serotonin is released from the presynaptic neuron into the synapse.
  • It then binds to receptors on the postsynaptic neuron, transmitting the signal.
  • Normally, serotonin is reabsorbed (reuptaken) by the presynaptic neuron.
  • SSRIs block this reuptake, preventing serotonin from being reabsorbed.
  • As a result, more serotonin remains in the synapse, increasing its effect on the postsynaptic neuron and improving mood regulation, which helps reduce OCD symptoms.
• Combining SSRIs with other treatments

  SSRIs are often combined with CBT to provide a more effective treatment. SSRIs reduce anxiety and compulsive behaviors, allowing patients to better engage in CBT, which targets the underlying thought patterns. This combination addresses both the biological and psychological aspects of OCD, leading to better symptom control.
• Alternatives to SSRIs - Tricylics

  Tricyclics, such as clomipramine, are sometimes used. These act on various systems, including the serotonin system, which has the same effect as SSRIs. Clomipramine has more severe side effects than SSRIs, so it is generally kept in reserve for people who do not respond to SSRIs.
• Alternatives to SSRIs - SNRIs

  SNRIs have more recently been used to treat OCD. Like clomipramine, they are a second-line treatment for people who do not respond to SSRIs. They increase serotonin levels as well as noradrenaline, which is another neurotransmitter involved in mood regulation.
• Strength of D.T - Cost-effective and non-disruptive

  SSRIs are cost-effective, making them a good option for public health systems like the NHS, as they are less expensive than other treatments, such as long-term therapy. They are also non-disruptive, as patients can take them in pill form without major changes to their daily routine, which is convenient for those managing OCD in everyday life.
• Limitation of D.T - Serious side-effects

  A significant limitation of drug treatments for OCD is the serious side effects they can cause. SSRIs may lead to nausea, sexual dysfunction, and, in rare cases, serotonin syndrome. Tricyclics such as clomipramine can cause erection problems, weight gain, heart issues (1 in 100 people), and aggression. These side effects can make it difficult for patients to continue treatment and may limit the effectiveness of the medication.