OCD

• what is OCD?

  a disorder in which a person has recurrent and unwanted thoughts and a need to perform repetitive and rigid actions, or both.
• obsessions vs compulsions

  obsessions:

  • internal
  • thoughts= an idea, impulse or mental image that is repetitive, feels intrusive and causes anxiety.

  compulsions:

  • external
  • actions= a mental/behavioural act that is rigid, feel compelled to do, reduces/neutralises the anxiety.
• what are some behavioural symptoms/characteristics of OCD?

  performing repetitive behaviours e.g. cleaning (rituals)
• what are some cognitive symptoms/characteristics of OCD?

  • hypervigilance- e.g. looking for dirt.
  • catastrophic thoughts- e.g. exaggerating the danger, "i could die if i don't wash germs from my hands."
  • selective attention- specifically attending to the anxiety generating stimuli e.g. dirt
• what are some emotional characteristics of OCD?

  feeling anxious, low mood, worry, distress.
• what are the 3 biological explanations of OCD?

  genetic, neuranatomic, biochemical.
• what is the biochemical explanation of OCD?

  proposed that there is a genetic component to OCD which predisposes some to OCD.
• what are candidate genes?

  genes that through research have been implicated in development of OCD. can cause an alteration in neurotransmitters.
• what are the candidate genes associated with OCD?

  • SERT- affects transport of serotonin, creating lower levels of serotonin.

  low levels of serotonin have been associated with OCD.

  
  

  • COMT- helps to reduce the action of dopamine. variation of the gene is found in OCD paitents that decreases the amount of COMT and therefore dopamine isn't controlled= too much dopamine.

  high levels of dopamine have been associated with OCD.
• how does serotonin affect people with OCD?

  low levels= anxiety
• how does dopamine affect people with OCD?

  high levels= addiction/pleasure from repeating behaviours.
• what is the concordance rate for OCD in the general population?

  2%
• how have twin studies explained OCD?

  genetics:

  nestadt (2010)-

  reviewed previous exisiting twin studies.

  • MZ OCD concordance= 68%
  • DZ OCD concordance= 31%

  therefore we can assume there is a genetic link to OCD as the concordance rate is higher in MZ twins who are more genetically similar.
• how have family studies explained OCD?

  nestadt (2000):

  • 80 paitents with OCD and 343 of their near relatives compared w/ control group w/ out mental illness and their relatives.
  • strong link w/ 1st degree relatives- 5x greater risk if had 1st degree relative who has OCD.
• what is the definition of concordance rate?

  a measure of genetic similarity.
• what is the diathesis stress model?

  psychological concept that a disorder is due to interaction between

  a predisposed vunerability (diathesis) and environmental trigger later in life.
• what is the neuroanatomic explanation of OCD?

  the worry loop:

  3 specific areas of the brain- thalamus, OFC and caudate nucleus.

  • overactive thalamus= increased motivation to clean/check for safety.
  • overactive OFC= increased anxiety and increased planning to avoid anxiety.
  • damaged caudate nucleus= minor worry signals not supressed, so worry signals become increasingly excited, increasing compulsive behaviour and anxiety.
• how are antidepressants (SSRI's) used to treat OCD?

  low levels of serotonin.

  • the drugs increase levels of serotonin by blocking reuptake in pre-synaptic neuron.
  • this prolongs activity in synapse to normalise worry loop.
  • reduces anxiety experienced due to obssessions emotional symptoms.

  trade name e.g.- prozac