Suggests that OCD runs in families
although what is passed down could
be more commonly known as
genetic vulnerability.
Candidate Genes
Genes which have been
implicated in the development
of OCD.
E.G The SERT gene which is involved
with regulating serotonin
E.G The COMT gene, regulating the
function of dopamine.
OCD is polygenic
Caused by the
development of as many
as 230 genes
Different types of OCD
One group of genes may cause
OCD in one person but a
different group may cause the
disorder in another person.
Evaluation
Strengths
Research support.
Nestadt et al (2010) reviewed twin studies.
Found that 68% of identical twins shared
OCD but only 31% of non identical.
Marini and Stebnicki (2012) Family studies. Found that
when one family member is diagnosed with OCD, the rest
are 4 times as likely to be diagnosed.
Weaknesses
Environmental Factors
Individuals may gain vulnerability to OCD
through an environmental stressor.
Cromer (2007) found that over half of the
OCD patients in the sample developed
OCD after a traumatic event in the past.
Too many genes involved to
pinpoint specific ones.
Neural Explanations
Abnormal levels of certain
neurotransmitters
If a person has low levels of serotonin then normal
transmission of mood-relevant information does not
take place and a person may experience low moods.
Certain brain circuits may be
faulty
Basal Ganglia
Hypersensitivity of basal ganglia
results in a rise of repetitive motor
behaviours.
Orbitofrontal Cortex and Thalamus
Involved with decision making. An overactive
thalamus would result in increased motivation to
clean or check for safety. An overactive OFC means increased anxiety.
Evaluation
Strengths
Antidepressants which work purely on
serotonin help in reducing OCD symptoms
suggesting serotonin is involved in the process
of OCD.
Brains of OCD patients are
structured differently which can
be seen in brain scans.
Weaknesses
Cant distinguish whether low
dopamine is a factor in OCD or just an
effect of OCD.