Biological approach to explaining OCD

• What are candidate genes believed to be involved in?

  The development of OCD
• How do candidate genes influence OCD?

  They are associated with traits increasing OCD likelihood
• What is the SERT gene also known as?

  CertGene
• What does the SERT gene regulate?

  Serotonin levels in the brain
• How do variations in the SERT gene affect OCD susceptibility?

  They alter serotonin transport and brain function
• What role does the 5HT1Dβ gene play in OCD?

  It is involved in serotonin transmission
• What is indicated by variations in the 5HT1Dβ gene?

  Increased susceptibility to OCD
• What does "OCD is polygenic" mean?

  It is influenced by multiple genes
• What does the identification of over 230 genes suggest about OCD?


  It is a complex disorder with many genetic factors
• How does serotonin function in relation to OCD?

  It regulates mood, anxiety, and impulse control
• What problems may arise from serotonin dysfunction in OCD?

  Issues in brain circuits regulating behavior
• How does serotonin dysregulation affect brain communication in OCD?

  It disrupts communication between key brain regions
• What is often observed in decision-making for individuals with OCD?

  Dysfunctional decision-making
• Which brain region is linked to decision-making in OCD?

  The orbitofrontal cortex (OFC)
• How does the orbitofrontal cortex relate to OCD symptoms?


  It is often overactive, causing excessive worry
• What is the function of the caudate nucleus in the brain?

  It helps filter out irrelevant information
• What dysfunction in the caudate nucleus is associated with OCD?

  Inability to suppress obsessive thoughts
• What results from the dysfunction of the caudate nucleus in OCD?


  Repetitive and intrusive obsessive thoughts
• Supporting evidence for the biological approach to explaining OCD comes from Nestadt et al.'s review of twin studies, which found that 68% of identical twins (monozygotic) share OCD, compared to only 31% of non-identical twins (dizygotic). This suggests a strong genetic component, as identical twins share 100% of their genes while non-identical twins share only 50%. This high concordance rate in identical twins supports the idea that certain genetic factors may predispose individuals to develop OCD. However, it is important to recognize that genetics alone do not determine whether someone will develop OCD. The diathesis-stress model highlights that genetic vulnerability must interact with environmental stressors for the disorder to manifest. Therefore, while the findings support the biological theory, they also acknowledge the role of environmental factors and prevent the theory from being overly deterministic.
• A strength of the biological approach to explaining OCD is its real-life application in treatments like SSRIs and tricyclics. These medications increase serotonin levels in the brain, which is linked to reducing OCD symptoms. Research shows that SSRIs are effective for around 60-70% of patients, helping improve their quality of life. Tricyclics, though older, also target serotonin but with additional effects. While these treatments can be effective, they may not work for everyone and can have side effects. Nevertheless, they show how understanding the biological basis of OCD can lead to practical treatments, benefiting many people.
• A limitation of the biological approach to explaining OCD is highlighted by Cromer et al. (2007), who found that over half of OCD patients in their study had experienced a traumatic event in the past, suggesting that environmental factors play a significant role in the development of OCD. This challenges the biological explanation, which focuses primarily on genetic and neurobiological factors, and suggests that OCD may not be solely determined by biological factors. The fact that trauma and stressful life events can contribute to the onset of OCD implies that the biological approach may be too reductionist, ignoring the impact of environmental and psychological factors. Therefore, this suggests that a more holistic approach, integrating both biological and environmental factors, would provide a fuller understanding of OCD.
• A limitation of the biological explanation of OCD is the difficulty in establishing cause and effect for neural aspects. For example, research shows abnormalities in the orbitofrontal cortex and basal ganglia in OCD patients, as well as serotonin imbalances. However, it’s unclear whether these brain abnormalities cause OCD or result from it. This raises concerns about the validity of biological explanations, as the relationship between neural factors and OCD remains correlational rather than causal. Studies, therefore, do not establish a clear cause of OCD, weakening the reliability of the biological approach.
• What does it mean if OCD is aetiologically heterogenous?

  Different gene variations can cause OCD