Biological approach to explaining OCD & treating OCD

Explaining OCD

The biological approach to explaining obsessive compulsive disorer (OCD) addresses both genetic and neural explanations.

• Genetic explanations suggest that OCD is inherited and that individuals receive specific genes from their parents which influence the onset of OCD
• Neural explanations suggest that abnormal levels of neurotransmitters (serotnin and dopamine) and certain regions of the brain are implicated in OCD

Genetic Explanation

Genetic explanations have focused on identifying specific candidate genes which are implicated in OCD. It is believed that OCD is a polygenic condition, which means that several genes are involved

Taylor (2003) suggests that as many as many as 230 genes may be involved in the condition and prehaps different genetic variations contribute to the different types of OCD, e.g. hoarding or obsession with religion. Two examples of genes that have been linked to OCD are the COMT gene and SERT gene

The COMT gene is associated with the product of catechol-O-methyltransferase (COMT), which regulates the neurotransmitter dopamine

Although all genes come in different forms, one variation of the COMT gene results in higher levels of dopamine and this variation is more common in patients with OCD, compared to people without OCD

Secondly, the SERT gene (5-HTT gene) is linked to serotonin and affects the transport of this neurotransmitter (SERotonin Transporter). Transportation issues cause lower levels of serotonin to be active within the brain and are associated with OCD (and depression)

Ozaki et al (2003) published results from a study of two unrelated families who both had mutation of the SERT gene. It concided with six out of seven of the family members having OCD

Neural Explanations

Neurotransmitters

The neurotransmitter serotonin is believed to play a role in OCD. Serotonin  regulates mood and lower levels of serotonin are associated with mood disorders, such as depression. Some cases of OCD are also associated with the reduced levels of serotonin, which may be caused by the SERT gene

Evidence for the role of serotonin in OCD comes from research examining antidepressants (SSRIs) such as that conducted by Piggott et al (1990) who found that drugs which increase the level of serotonin in the synaptic gap are effective in treating patients with OCD

In addition, the neurotransmitter dopamine has also been implicated in OCD. In contrast to serotonin, higher levels of dopamine have been associated with some of the symptoms of OCD, in particular, the compulsive disorders

Brain Structure

It is believed that several regions in the frontal lobes of the brain have abnormal brain circuits in patients with OCD. Two brain regions implicated specifically in OCD are: the basal ganglia and orbitofrontal cortex

The basal ganglia is a cluster of neurons at the base of the forebrain, which is involved in multiple processes, including the coordination of movement. Patients who suffer head injuries in this region often develop OCD-like symptoms

The orbitofrontal cortex is a region which converts sensory information into thoughts and actions. PET scans have found higher activity in the orbitofrontal cortex in…