explaining OCD

    Cards (17)

    • OCD can be inherited from parents
    • 230 - candidate genes found more frequently in people with OCD e.g SERT gene - affects reuptake in the serotonin system
    • OCD is polygenetic
    • Evidence for heritability of OCD coming from family

      in general population likelihood of OCD is 2% - however, the more closely genetically you are related to someone means higher concordance
      • first degree relative - 10%
      • Dz twin - 31%
      • Mz twin - 68%
    • Neural explanation - biochemical causes and an imbalance of neurotransmitters
    • Low levels of serotonin

      are thought to cause obsessive thoughts - low levels of serotonin are thought to be removed too quickly from synapse before it can transmit a signal
    • presynaptic neurons

      release neurotransmitters and receptors in the postsynaptic neuron detect these - if signal is strong enough
      then message is passed on and taken back up to the presynaptic neuron by reuptake
    • if the process happens too quickly people with OCD will have a reduced serotonin level in the synapse - the SERT gene is responsible got serotonin transportation in the synapse
    • Neural structure - worry circuit
    • Obitofrontal cortex (OFC) - rationalises decision making
    • basal ganglia system - caudate nucleus and the thalamus
    • communications in the worry circuit appears to be overactive in people with OCD
    • in normal circuit basal ganglia filters out minor worries from the OFC - if overactive small worries get to thalamus, being passed back to OFC forming a loop
    • repetitive motor functions
      attempt to break this loop - may give temporary relief but worry circuit will soon resume
    • issues in family and twin studies
      twins have similar environments - Mz twins will be treated more similarly than Dz twins . - concordance rate for Mz is 68% although they share 100% of genetics suggesting OCD cannot be completely determined by biological factors and there are some enviromental
    • Diathesis stress response may be a more valid explanation
      OCD is inherited genetic through genetic vulnerability - disorder does not develop unless there is an environmental stressor
      • research - 54% of 265 participants with ocd have one traumatic life events - those with trauma saw more severity of OCD symptoms
    • neuroimaging - using PET scans

      Pet scanners - show hyperactivity of the OFC in people with OCD while scanning brain at rest and when symptoms stimulates - however, this is a correlation study - researchers cannot be sure if this is a consequence of ocd or if the is a cause of ocd
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