Biological approach: Explaining and treating OCD

Genetic explanation

• Found that first degree relatives of people with OCD have a greater vulnerability to OCD

• Nedstadt et al (2000) found that first degree relatives of OCD have a 12% chance of OCD over 3% with the general population, hence could be a genetic predisposition to developing OCD

• Found that candidate genes responsible for regulating the production of serotonin has implications in OCD

• One such impaired gene is the SERT gene, if this is impaired it leads to problems with the transport of serotonin, ultimately leading to diminishing levels of serotonin correlating with OCD

• Another candidate gene is an impaired COMT gene which regulates the production of dopamine, an impaired COMT leaves too much dopamine in the synapse leading to compulsive behaviours associated with OCD

Evaluation points for the genetic explanation

Support evidence +

Research -

Promotes science +

Biologically reductionist -

Neural explanation

Several areas of the frontal lobe are thought to be abnormal in people with OCD, the caudate nucleus normally suppresses signals from the orbital Frontal Cortex

In turn the OFC sends signals to the thalamus about things such as worrying or a potential germ hazard, when the caudate nucleus is damaged, it fails to supress minor worry signals the thalamus is alerted which in turn signals back to the OFC acting as a worry circuit

The role of low serotonin

• Lower levels of the neurotransmitter serotonin which influences mood regulation, anxiety, sleep and social behaviour has been linked to OCD

• The exact influence of lower level’s of serotonin is unclear, although one possibility is that serotonin prevents behaviour repetition and therefore low levels of this neurotransmitter may be linked to the compulsions that can be displayed as a symptom of OCD

The role of low dopamine

• Additionally dopamine is abnormally high in individuals with OCD, high levels of dopamine have been thought to influence concentration

• May explain why OCD individuals experience an inability to stop focusing on obsessive thoughts and repetitive behaviours

Evaluation points for Neural explanation

Research support +

Cannot establish cause and effect -

Practical applications +

Scientific +

Drug therapy: SSRI’s

(selective serotonin reuptake inhibitors)

• Reduce the rate of reabsorption of serotonin making more available in the synaptic gap, prevents serotonin going back into the pre-synaptic neuron, leaving it in the synapse (helping to reduce OCD symptoms)

• Due to the increased availability, some serotonin receptors on the dendrites that are actually inhibitory reduce in number, its called down regulation

• This process ultimately make each serotonin fire more rapidly, further increasing serotonin levels, this neuroadaptation takes a few weeks to occur but alleviates OCD symptoms

Evaluation points

Evidence +

Unwanted side effects -

Cost effective +

Temporary solution -

Scientific +