biological approach to explaining

• What is the genetic explanation for OCD?

  Identifying specific candidate genes implicated in OCD.
• What does it mean for OCD to be a polygenic condition?

  Several genes are involved in OCD.
• How many genes may be involved in OCD according to Taylor (2003)?

  As many as 230 genes.
• What is the term for different genetic variations contributing to different types of OCD?

  Aetiologically heterogenous.
• How does genetic variation contribute to different types of OCD?


  Different genetic variations may contribute to different types of OCD.
• What are two examples of genes linked to OCD?

  COMT gene and SERT gene.
• What is the full name of the COMT gene?

  Catechol-O-methyltransferase.
• What does the COMT gene regulate?

  The neurotransmitter dopamine.
• What variation of the COMT gene is more common in patients with OCD?

  The variation that results in higher levels of dopamine.
• What neurotransmitter is linked to the SERT gene?

  Serotonin.
• What does the SERT gene affect?

  The transport of serotonin.
• What is the full name of the SERT gene?

  Serotonin Transporter (5-HTT) gene.
• What happens when there are transportation issues with serotonin?

  Lower levels of serotonin are active within the brain.
• What is a strength of the biological explanation of OCD?

  Research support seen in family studies.
• What percentage of patients with OCD had parents with the disorder according to Lewis (1936)?


  37%.
• What percentage of patients with OCD had siblings who suffered from the disorder according to Lewis (1936)?


  21%.
• What did Nestadt et al. (2000) propose about individuals with a first-degree relative with OCD?

  They are up to five times more likely to develop the disorder.
• What is a weakness of the genetic explanation of OCD?

  It seems that a diathesis-stress model may be more appropriate in explaining OCD
• What is a diathesis-stress model?

  A model that explains the development of disorders through a combination of genetic vulnerability (diathesis) and environmental stressors.
• How does the diathesis-stress model apply to OCD?

  In OCD, genes act as a diathesis and trauma acts as a stressor to develop the disorder.
• What did Cromer et al. (2007) find about OCD patients?

  Over half of the OCD patients in their sample had a traumatic event in their past.
• What did Cromer et al. (2007) find about the severity of OCD?

  OCD was more severe in those with more than one trauma.
• What does pathoplastic mean in relation to OCD?


  It means that OCD can vary in symptomology and severity depending upon a person's life events.
• What are neurotransmitters?


  Chemicals that transmit signals between nerve cells.
• How are levels of serotonin associated with OCD?

  Some cases of OCD are associated with reduced levels of serotonin.
• What did Pigott et al. (1990) find about anti-depressants and serotonin?


  Anti-depressants that increase serotonin activity reduce obsessive symptoms in patients.
• What have antidepressants that do not increase serotonin activity been shown to do for patients with OCD?


  They have been found to be ineffective for OCD.
• What physical evidence supports serotonin's involvement in OCD?

  PET scans have found low levels of serotonin in sufferers.
• What is the association between levels of dopamine and OCD symptoms?


  Higher levels of dopamine have been associated with some symptoms of OCD, particularly compulsive behaviors.
• What did Szechtman et al. (1998) find about dopamine and OCD-like behaviors?


  When rats were given drugs that increased dopamine, their behaviors resembled obsessive behaviors found in people with OCD.
• What areas of the brain have been associated with OCD?

  The basal ganglia and orbitofrontal cortex
• What is the basal ganglia?

  A cluster of neurons at the base of the forebrain involved in multiple processes, including movement coordination.
• What happens when patients suffer head injuries in the basal ganglia region?

  They often develop OCD-like symptoms.
• What did Max et al. (1994) find about the basal ganglia and OCD-like symptoms?

  When the basal ganglia is disconnected from the frontal cortex during surgery, OCD-like symptoms are reduced.
• What is the orbitofrontal cortex responsible for?

  Converting sensory information into thoughts and actions.
• What did PET scans find about the orbitofrontal cortex in patients with OCD?

  Higher activity in the orbitofrontal cortex when exposed to triggers like holding a dirty item with a potential germ hazard.
• What is the role of the caudate nucleus in OCD?

  The caudate nucleus, located in the basal ganglia, is responsible for suppressing signals from the orbitofrontal cortex.
• What happens when the caudate nucleus is damaged or abnormal?

  It fails to suppress minor 'worry' signals, alerting the thalamus, which signals the orbitofrontal cortex, creating a 'worry circuit'.
• What is a strength of the neural explanation of OCD?

  Real life applications in the form of drug therapy.
• What are SSRIs?


  Selective serotonin reuptake inhibitors, a type of antidepressant.