biological explanation

• biological approach


  The biological approach is also known as the medical model and sees abnormal conditions as being similar to physical illnesses caused by abnormal biological processes. 

  Neural explanations: abnormal level of neurotransmitters and damaged regions of the brain.

  Hereditary differences: genetic transmission.

  The genetic and neural explanations for OCD are not unconnected. It may be that some underlying genetic abnormality is causing structural and functional differences in the brain. 
• genetic explanation : candidate genes


  Some mental disorders appear to have a stronger biological component than others which means that OCD may be genetically inherited. 

  Genetic explanations are focused on identifying specific candidate genes which are implicated in OCD. Candidate genes are those which have been linked to certain diseases, there two that have associations with OCD.

  
• genetic explanations : polygenic


  It is believed that OCD is a polygenic condition, which means that several genes are involved. 

  Researcher Taylor (2013) had analysed findings of previous studies (meta- analysis) and found evidence that there may be up to 230 genes involved in OCD.

  Genes that have been studied in relation to OCD include those associated with the action of dopamine as well as serotonin as both are believed to have a role in regulating mood.
• genetic explanation : research


  Research suggests that 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 (higher concordance rates with first-degree relatives), although what is passed on from one generation to the next is genetic vulnerability, not the certainty of OCD. 
• Diathisis-stress model


  Diathisis-stress model

  • certain genes leave some people with an increased risk of suffering a mental health disorder, but it is not certain – some environmental stress (experience) is necessary to trigger the condition.
• neurochemistry : serotonin and dopamine


  Serotonin regulates mood and lower levels of serotonin are associated with mood disorders, such as depression. Its also associated with the reduced levels of serotonin, which may be caused by the SERT gene. support for this in OCD comes from research examining anti-depressants, which have found that drugs which increase the level of serotonin are effective in treating patients with OCD.

  Dopamine has also been implicated in OCD, with higher levels of dopamine being associated with some of the symptoms of OCD, in particular the compulsive behaviours.
• neural (brain) structure : basal ganglia


  The basal ganglia is a brain structure involved in multiple processes, including the coordination of movement. 

  Patients who suffer head injuries in this region often develop OCD-like symptoms, following their recovery.
• neural (brain) structure : basal ganglia research


  Max et al. (1994) found that when the basal ganglia is disconnected from the frontal cortex during surgery, OCD-like symptoms are reduced, providing further support for the role of the basal ganglia in OCD.
• neural (brain) structure : orbitofrontal cortex


  The orbitofrontal cortex is a region which converts sensory information into thoughts and actions. 

  PET scans have found higher activity in the orbitofrontal cortex in patients with OCD.

  Heightened activity in the orbitofrontal cortex increases the conversion of sensory information to actions (behaviours) which results in compulsions.