OCD explanation

• OCD is an anxiety disorder that causes repetitive thoughts and behaviours
• Someone with contamination ocd may wash their hands and belongings more than necessary
• Someone with ocd may feel as if bad things will happen if they dont do a compulsion
• A compulsion is a repeated behaviour
• An obsession is a repetitive thought
• Ocd has emotional, behavioral and cognitive characteristics
• The anxiety caused by ocd can lead to depression as compulsions interrupt daily life
• Those with ocd are often hypervigilant of anxiety causing stimuli
• Many people with ocd are aware that their thoughts and actions are not rational
• OCD can be explained through specific genes, such as COMT and SERT
• The COMT gene regulates the production of dopamine
• The SERT gene affects the transport of seretonin
• One form of COMT is more common in patients with OCD than those without, leading to higher levels of dopamine
• Lowered levels of serotonin are implicated in OCD
• The diathesis-stress theory states that no one gene controls OCD but can create a vulnerability for it.

  Other stressors affect what develops
• OCD can be explained through differences in brain circuits / neurotransmitters
• Dopamine levels are higher with OCD.

  When animals are given enhanced dopamine levels, they show compulsive behaviours similar to OCD
• Serotonin levels are lower with OCD.

  when given antidepressents that increase sereronin, patients show a reduce in OCD symptoms
• When someone dosent have OCD:

  OFC [orbitofrontal cortex] sends a 'worry' signal to the thalamus.

  Minor 'worries' are suppressed by the caudate nucleus and don't reach the thalamus
• When someone does have OCD:

  The OFC [orbitofrontal cortex] sends a 'worry' signal to the thalamus.

  The caudate nucleus is not able to suppress the 'worry'.

  Thalamus sends the signal back to the OFC, creating a worry circuit
• One weakness of the genetic explaination of ocd is that the gene thought to be causing ocd is also found in patients with tourettes or autism. The gene cannot cause ocd, just a predisposing factor
• One strength of the genetic explaination for ocd is that: Studies show that people with a first degree relative with ocd are 5× more likely to develop ocd than the general population
• Twin studies show that [if the co-twin has ocd] a monozygotic twin is 2× more likely to develop ocd than a dizygotic twin.

  however, concordance rates are never 100%, there must be an environmental factor
• One strength of the genetic explaination is its real world application.

  Fertilised eggs can be tested for ocd 'causing' genes [however this has ethical issues]
• One weakness of the genetic explanation for ocd is that it is reductionist, it assumes that the relationship between ocd and genes is simple
• Ocd is a polygenic disorder, it is caused by various genes/neurotransmitters
• Candidate genes make someone more likely to develop ocd [eg. SERT]
• A - presynaptic neuron

  B - postsynaptic neuron

  C - vesicles

  D - transporter proteins [reuptake]

  E - synaptic gap

  F - neurotransmitter