Biological Explanations of OCD

Question 1

Basic View of Biology of OCD

Answer 1

There’s an issue w/ thinking, emotion and behaviour due to brain abnormalities

Either 1 or more parts are structurally or functionally (too active or not active enough) abnormal

OCD seems to have a stronger biological component than other mental illnesses

Question 2

OCD runs in families - Genetic Expl.

Answer 2

Lewis (1936) observed his OCD patients

Found - 37% had parents w/ OCD + 21% had siblings w/ it
=> SUGGESTS OCD does - genetic vulnerability gets passed through generations not certainty

*Diathesis-stress model says certain genes leaves some more likely to develop a disorder but environment triggers illness

Question 3

A particular gene is linked to OCD by researchers - Genetic Expl.

Answer 3

• Candidate genes create vulnerability for OCD - some involve regulating development of the serotonin system
  e. g. gene 5h1-D beta is implicated in transporting serotonin across synapes

Question 4

OCD is Polygenic - Genetic Expl.

Answer 4

• Not caused by single gene but by combo of genetic variation that significantly increase vulnerability

=> Taylor’s 2013 analysis of previous studies found up to 230 genes are involved

• they regulate action of dopamine + serotonin => neurotransmitters that regulate mood

Question 5

Aetiologically Heterogenous - Genetic Expl.

Answer 5

One group of genes may cause OCD an 1 person but a diff group of genes cause OCD in another

=> The orgins (aetiology) of OCD vary from one person to another (heterogenous)

• Also evidence to suggest diff types of OCD may result of particular genetic variations e.g hoarding disorder vs religious obsession

Question 6

Role of Serotonin - Neural Expl

Answer 6

• Low levels of serotonin available in synapses
  => normal transmission of mood relevant info. not relayed
  => cause low moods + affect other mental issues

Question 7

Decision-making Systems - Neural Expl.

Answer 7

• Some cases associated w/ this being impaired => abnornal functioning of lateral of frontal lobes (responsible for logical thinking)

=> Also evidence to suggest the left parahippocampal gyrus - associated w/ processing unpleasant emotions - funtions abnormally

Question 8

Twin Studies

Answer 8

A way to study genetic influence on psychological characteristics
=> Psychologists compare identical twins (monozygotic) where 1 has a disorder to non-identical twins where 1 does

Question 9

Concordance in Twin Studies

Answer 9

Where identical twins (MZ) are more likely to share a characteristic like OCD than non-identical (DZ)

=> Strongly SUGGESTS genes are involved in the disorder (diff must be due to genes as both twins where in similar environment)

Question 10

Research Support - Genetic AO3 (S)

Answer 10

Nestadt et al (2010) - reviewed previous twin studies + found 68% of identical twins shared OCD v 31% of non identical

=> strong support for genetic influence in OCD

Question 11

Family Studies - Genetic AO3 (S)

Answer 11

Marini + Shebrinicki (2012)
- found that a person w/ a family member diagnosed w/ OCD is 4x likely to develop it than those w/o one
=> suggests genetic influnce in OCD