Lesson 12 - Biological causes of OCD

Question 1

What are the genetic causes of OCD?

Answer 1

• The COMT gene
• The SERT gene

Question 2

The COMT gene

Answer 2

• a candidate gene for OCD
• results in high dopamine (high levels of drive, motivation and aggression)
• more common in those with OCD than those without.

Question 3

The SERT gene

Answer 3

• results in low serotonin levels, which is associated with low levels of happiness.

Question 4

Neuroanatomy by Jenike and Rauch

Answer 4

• Found a relationship between brain damage and OCD
• The brain damage could be caused by a virus
• the damage could effect the short term memory (“I can’t remember if i locked the front door.” Results in compulsions
• From PET scans, it shows that when an OCD patient is exposed to something dirty, the frontal lobes and basal ganglia may be overactive.

Question 5

The basal ganglia

Answer 5

• responsible for voluntary motor movements, habit learning, eye movements, and over activity could result to repetitive motor functions. Common in Tourette’s.

Question 6

Neurotransmitters

Answer 6

• Low serotonin results in can cause depressive like symptoms
• Low levels can cause the caudate nucleus to malfunction
• High levels of dopamine can be linked to overactivity in the basal ganglia

Question 7

Rapoport (1990)

Answer 7

• supports the neural explanation
• He reviewed the “Great Sleeping Sickness” of 1916-1918, and found a viral brain infections across Europe at the time.
• there was a rise on OCD symptoms as a result
• supports the link between brain damage and OCD

Question 8

Weaknesses of the neural explanation

Answer 8

• neurotransmitters may be the effect of OCD and not the cause
• levels of dopamine as a cause can be argued, as it can also cause other mental illnesses like schizophrenia. Not enough evidence to support it

Question 9

Ciccerone (2000)

Answer 9

• when patients were given the drug Risperidone, it resulted in lower dopamine levels and alleviated OCD symptoms