The biological approach

• Twin studies:

  • Monozygotic twins share 100% of their DNA as they have the same genotypes
  • Dizygotic twins share 50% of their DNA
  • ℳ𝒾𝑔𝓊ℯ𝓁 ℯ𝓉 𝒶𝓁 - studies both types of twins and found a 53-87% chance of one MZ twin developing OCD and then the other twin following, whereas there was a concordance rate of 22-47% in DZ twins, suggesting a genetic link.
• Family studies:

  • Genes are individually vulnerable to OCD.
  • 𝐿𝑒𝑤𝑖𝑠 - found 37% of OCD patients had parents with OCD and 21% had siblings with OCD.
  • Diathesis stress - certain genes leave people vulnerable to suffering a mental disorder but it is not certain that environmental stressors are necessary to trigger it.
  • Runs in the family.
• OCD is polygenic:

  • OCD is not caused by one single gene, but several genes are involved.
  • 𝒯𝒶𝓎𝓁ℴ𝓇 - analysed finding of previous studies and found evidence to 230 genes being involved in OCD.
• Candidate Genes:

  • Create vulnerability for OCD.
  • COMT gene - regulates the neurotransmitter dopamine.
  • 𝑇𝑢𝑐𝑘𝑒𝑟 𝑒𝑡 𝑎𝑙 - found one form of the COMT gene to be more common in OCD patients.
  • SERT gene - affects the transmission of serotonin, leading to lower levels in the brain.
  • ℬℯ𝓃𝑔𝒶𝓁 ℯ𝓉 𝒶𝓁 - patients with OCD were more likely to carry two copies of the long allele of the SHTT gene compared to the control.
• Different types of OCD:

  • A etiologically heterogenous - the causes (aetiology) of OCD has different origin (heterogenous).
  • Different types of OCD may be the result of particular genetic variations such as hoarding disorder and religious obsessions.
• S̆̈t̆̈r̆̈ĕ̈n̆̈ğ̈t̆̈h̆̈s̆̈

  • Supporting research - 𝑁𝑒𝑠𝑡𝑎𝑑𝑡 𝑒𝑡 𝑎𝑙 - reviewed twin studies and found a higher concordance rate in MZ twins so there’s a genetic influence.
  • Practical applications - 𝒮𝓉ℯ𝓌𝒶𝓇𝓉 ℯ𝓉 𝒶𝓁 - SERT gene can be screened for to predict OCD suggesting there’s a genetic link.
• L̑̈ȋ̈m̑̈ȋ̈t̑̈ȃ̈t̑̈ȋ̈ȏ̈n̑̈s̑̈ ̑̈

  • Cannot factor out the role of the environment - relationship between genetics and OCD isn't clear cut.
  • Too many candidate genes to say that only one gene influences OCD.
  • Reductionist - OCD is very complex and there other approaches you can look at such as the two process model and it’s not looking at individuals holistically.
• 𝓝𝓮𝓾𝓻𝓸𝓽𝓻𝓪��𝓼𝓶𝓲𝓽𝓽𝓮𝓻𝓼:

  Your genetic makeup can affect levels of neurotransmitters in the brain. They pass information from one neuron to another.
• Dopamine:

  High levels of dopamine are linked with OCD. Dopamine is the motivation rewards and compulsions element. When a pleasurable experience occurs dopamine is released and feelings of pleasure are felt.
• Serotonin:

  Low levels of serotonin are linked with OCD. This regulates a number of the body’s functions including mood, anxiety, and memory. Antidepressant drugs increase levels of serotonin.
• The brain:

  • implicated in OCD in orbitofrontal cortex.
  • The OFC sends signals to the thalamus about things that are worrying.
  • if part of the basal ganglia is damaged it fails to stop minor worry signals and the thalamus is alerted.
• S͎t͎r͎e͎n͎g͎t͎h͎s͎:

  • Supporting research - 𝙎𝙖𝙭𝙚𝙣𝙖 𝙖𝙣𝙙 𝙍𝙖𝙘𝙝 - reviewed studies Of OCD that used PET and MRI scans and found that there was a link between OCD and the brain.
  • Practical applications - SSRIs increase the amount of seratonin. 𝚂𝚘𝚘𝚖𝚛𝚘 𝚎𝚝 𝚊𝚕 reviewed 17 studies and found that SSRIs were more effective than placebos.
• ͓̽L͓͓̽̽i͓͓̽̽m͓͓̽̽i͓͓̽̽t͓̽a͓͓̽̽t͓͓̽̽i͓͓̽̽o͓͓̽̽n͓͓̽̽s͓̽:

  • Relationship between the brain and OCD isn’t clear cut as there are inconsistent findings.
  • Problem with logic - 𝑳𝒂𝒄𝒂𝒔𝒔𝒆 𝒂𝒏𝒅 𝑳𝒆𝒐 - headaches are treated with aspirin, but there’s no evidence to suggest that there wold be a headache because of the lack of aspirin, so there could be other causes of OCD.
  • Reductionist - OCD is a very complex disorder so there are cognitive and behavioural aspects to consider other than biological aspects. Neurotransmitters are unlikely to be representative of a unique experience.
• Antidepressants: Selective Serotonin Reuptake Inhibitors (SSRIs)

  • Effective at treating OCD
  • Fluoxetine in adults and works by increasing the levels of serotonin in the synapse.
  • Can take up to 3-4 months after taking them to reduce symptoms.
• How do SSRIs work?

  • presynaptic cell sends information via a synapse.
  • Receptors on the surface of the postsynaptic cell recognise neurotransmitters and pass on the message.
  • 90% of neurotransmitters are released from the receiving receptors and taken up again by the sending cell.
  • Leads to repeated stimulation of the receptors on the post synaptic nerve ending, and higher levels of serotonin.
• Antidepressants: Serotonin-noradrenaline reuptake inhibitors (SNRIs)

  • works on serotonin and norepinephrine.
  • Used on patients that do not respond to SSRIs.
  • Increasing serotonin and noradrenaline in the synapse by slowing the rate that the brain breaks down the two neurotransmitters.
• 𝗦𝘁𝗿𝗲��𝗴𝘁𝗵𝘀 - Effectiveness

  • Research evidence - 𝓢𝓸𝓸𝓶𝓻𝓸 𝓮𝓽 𝓪𝓵 - reviewed 17 studies and found that SSRIs were more effective than placebos. Suggests that the use of drugs to threat OCD as it shows that its effective.
  • Quality of life - quickly improves the patients quality of life, symptoms improve in 50-80%.
• 𝙇𝙞𝙢𝙞𝙩��𝙩𝙞𝙤𝙣𝙨 - Effectiveness:

  • Motivational deficits - medication can stop the individual from working on other factors 𝑹𝒐𝒔𝒔 𝒂𝒏𝒅 𝑹𝒆𝒂𝒅 Said that prescribed medication can make them feel worse as it reduces their motivation.
  • Not long term - if they stop taking the drugs they revert back to their original levels.
  • Publication bias - may not be effective as drug companies just want a successful rate they dont care about the negative consequences of antidepressant drugs.
• 𝐒𝐭𝐫𝐞��𝐠𝐭𝐡𝐬 - appropriateness

  • easy to administer - quick and easy and takes little cognitive effort.
  • Removes blame - biological cause so patients feel more inclined to speak treatment.
  • Cost effective - NHS doesnt have to pay for therapists to be trained so its cheap to produce and can treat a lot f people quickly.
• 𝗟𝗶𝗺𝗶𝘁��𝘁𝗶𝗼𝗻𝘀 - appropriateness

  • Side effects- nausea, headaches, weight gain/loss, dizziness and insomnia.
  • Not appropriate for everyone - side effects and behavioural therapy may be more suitable.