>psychopathology - OCD - explanations

Question 1

genetic explanations of OCD? intro?

Answer 1

-genetic explanations suggest disposition of OCD may be inherited, investigated using family + twin studies
-COMPT + SERT gene thought to be associated with OCD

Question 2

COMPT gene?

Answer 2

-responsible for production of COMPT enzyme
-enzyme regulates levels of dopamine associated with symptoms of OCD
-one variation, common in OCD patients, causes less production of COMPT enzyme -> higher levels of dopamine

Question 3

SERT gene?

Answer 3

-seratonin transporter gene, responsible for the transportation of seratonin
-one variation leads to lower levels of seratonin
-linked to symptoms of OCD + depression

Question 4

research support for the impact of genes?

Answer 4

-Nestadt et al
-2000- 80 OCD patients + 343 near relatives compared to control group with no mental illness + their relatives
-found strong link between near family, 5x greater risk than general population if 1st degree relative had OCD
-2010- reviewed over past twin studies examining OCD, found 68% of identical + 31% non-identical twins experienced OCD

Question 5

neural explanations for OCD- abnormal levels of neurotransmitters, serotonin + dopamine

Answer 5

-dopamine, pleasure neurotransmitter, feelings of pleasure + addiction -> people repeat behaviours lead to dopamine increase
-serotonin, mood neurotransmitter, contributes to well-being + happiness, affected by exercise + light

Question 6

how do serotonin and dopamine lead to symptoms of OCD?

Answer 6

-high levels of dopamine linked to symptoms of OCD -> compulsive behaviours
-low levels of serotonin -> regulates mood, lower levels associated with mood disorders

Question 7

research support for neurotransmitters?

Answer 7

-antidepressants are an effective treatment for OCD
-work by increasing serotonin levels in the synapse
-effective at treating symptoms of OCD suggesting serotonin plays a role in OCD

Question 8

neural explanations- abnormal brain circuits, stages of typical worry cycle?

Answer 8

-worry detected in orbitofrontal cortex, message sent to thalamus
-caudate nuclei intercepts message, suppresses it
-thalamus receives message, sends back to OFC
-OFC interprets + co ordinates appropriate behaviour to deal with worry

Question 9

what is the typical role of caudate nuclei, compared to those in OCD patients?

Answer 9

-filter-screening, suppressing irrelevant impulses so only most important + powerful impulses sent to thalamus
-OCD patients -> damaged caudate nuclei -> can’t suppress irrelevant impulses -> increase in compulsive behaviour + anxiety

Question 10

role of neurotransmitters in worry cycle?

Answer 10

-serotonin plays a key role in operation of OFC + caudate nuclei, low levels -> malfunctioning in these areas of the brain
-dopamine = main neurotransmitter in basal ganglia -> where caudate nuclei located, high levels -> over stimulation/activity

Question 11

research support for abnormal brain circuits?

Answer 11

-PET scans show heightened activity in OFC in patients with OCD
-suggested that there is a link between gene + anatomic differences in the brain
-OCD patients + close relatives showed reduced grey matter in areas of brain, including OFC
-anatomical differences may be due to inheritance

Question 12

disadvantages of abnormal brain circuits?

Answer 12

-concordance rates not always 100%, could be due to other factors, Cromer found that over half of OCD patients had experienced a traumatic event in their past
-reductionist, ignoring other factors eg cognition + learning, 2 process model may also explain OCD
-difficulty determining cause + effect