OCD

• OCD affects approximately 1 in 50 people and its symptoms include obsessive thoughts and compulsive behaviours
• Obsessive thoughts are repetitive, distressing mental images or concerns that provoke anxiety
• Compulsions are actions that individuals feel they need to perform to reduce the discomfort caused by obsessive thoughts
• Relief caused by compulsions is only temporary, as obsessive thoughts quickly return
• Contamination/infection is an obsession that leads to cleaning hands or surfaces (compulsive)
• Burglary/fire (obsession) leads to checking doors are locked (compulsion)
• Genetic explanation to OCD suggests that predisposition to OCD is inherited from parents. Although there is no one OCD gene
• Genetic analysis has revealed around 230 separate candidate genes found more frequently in people with OCD
• Candidate genes influence the functioning of neural systems in the brain; e.g. the SERT gene affects the reuptake in the serotonin system
• Many candidate genes have been identified suggesting that OCD is polygenic, meaning a predisposition to OCD requires a range of genetic changes
• Evidence for heritability of OCD comes from family and twin studies
• • First degree relatives have a 10% concordance rate. Dizygotic twins have a 31% concordance rate. Monozygotic twins have a 68% concordance rate; suggesting the more closely related you are to a person with OCD, the more likely you are to inherit
• The neural explanation for OCD suggests that biochemical causes such as an imbalance of neurotransmitters and large neural structures in the brain
• Low serotonin levels are thought to cause obsessive thoughts
• Low levels of serotonin is likely due to it being removed from the synapse too quickly before it has been able to transmit its signal
• Presynaptic neurons release neurotransmitters. Receptors on the postsynaptic neurons detect these neurotransmitters. If the signal is strong enough, the message from the neurotransmitters is passed on. Neurotransmitters detach from the receptors and are taken back to the presynaptic neuron through a process called reuptake.
• Reuptake happens too quickly in people with OCD. e.g. the SERT gene is responsible for serotonin transportation in the synapse