OCD

• What is OCD?

  A condition characterised by obsessions and compulsive behaviours
• What is an obsession?


  A recurring thought or image
• What are compulsions?


  Repetitive behaviour e.g hand washing
• What are the 3 categories of OCD?

  1. Trichotillomania - compulsive hair pulling
  2. Hoarding disorder - compulsive gathering of possessions and the inability to part with anything regardless of its value
  3. Excoriation disorder - compulsive skin picking
• Behavioural Characteristics of OCD

  1. Compulsions are repetitive - e.g ordering groups of objects such as CD collections
  2. Compulsions reduce anxiety - 10% of people with OCD show compulsive behaviour where they have no obsessions but irrational anxiety
  3. Avoidance - Attempt to reduce anxiety by keeping away from situations that trigger it (people who wash compulsively may avoid coming into contact with germs) but it can lead people to avoiding ordinary situations e.g emptying their rubbish bins which can interfere with leading a regular life
• Emotional Characteristics of OCD

  1. Anxiety and distress - Obsessive thoughts and compulsions are unpleasant and frightening and creates anxiety
  2. Depression - OCD is accompanied by depression, so anxiety can be accompanied by low mood and lack of enjoyment in activities. Compulsive behaviour tends to bring some relief from anxiety but it's temporary.
  3. Guilt and disgust - irrational guilt over minor moral issues, or disgust, which may be directed against something external like dirt
• Cognitive characteristics of OCD

  1. Obsessive thoughts - e.g worries of being contaminated by dirt and germs
  2. Cognitive coping strategies - e.g a religious person tormented by obsessive guilt may respond by praying or meditating which may help manage anxiety
  3. Insight into excessive anxiety - People with OCD are aware that their obsessions and compulsions are not rational. Is necessary for a diagnosis of OCD. People with OCD experience catastrophic thoughts about worst case scenarios and tend to be hypervigilant (maintain constant alertness and keep attention focused on potential hazards)
• The Biological Explanation of OCD consists of what 2 types of explanations?

  1. Genetic Explanation- exploring the role of genes
  2. Neural Explanation- exploring the role of structures in the brain
• What are candidate genes?


  Genes which create a vulnerability for OCD
• What are the 2 types of candidate genes?

  1. COMT gene
  2. SERT gene
• What is the COMT gene?

  • Regulates the production of a neurotransmitter (dopamine)
  • In people with OCD it doesn't work (mutated)
  • Research compared 101 patients with OCD and 100 healthy PPs and the OCD group had lower activity of the COMT gene
• What is SERT gene?

  • Serotonin transporter that is mutated for people with OCD
  • Researchers have found a mutated SERT gene in 2 different families - 6 out of the 7 family member had OCD
• Genetic Explanation for OCD

  • OCD is polygenic - several genes are involved (evidence suggests there may be 230 genes involved in OCD)
  • Aetiologically heterogeneous - origin of OCD has many different genes involved (different genes may cause different types of OCD)
• What evidence is there to support the genetic explanation of OCD?

  1. Twin studies- OCD levels in monozygotic twins has a 68% concordance rate compared to dizygotic twins with a 31% concordance rate
  2. In the diathesis-stress model it suggests a genetic vulnerability causes some people to have a higher chance in getting OCD
• Genetic Explanation AO3: Supporting Evidence

  • OCD has a genetic basis
  • OCD concordance rates in monozygotic twins is 68%
  • OCD concordance rates in dizygotic twins is 31%
  • Genes may play a big factor in developing OCD
• Genetic Explanation AO3: Counterpoint to supporting evidence

  • If OCD was solely based on genetics then the OCD concordance rates for monozygotic twins would be 100%
  • This is not the case suggesting OCD may arise from other factors
  • An environmental trigger may also be needed to get OCD
• Genetic Explanation A03: Environmental factors

  • Genetics is not only involved in OCD
  • Research has found that in one study over half of the patients had experienced a traumatic event
  • The diathesis-stress model states that a genetic vulnerability along with an environmental trigger is needed for OCD to occur
  • Genes is only a partial explanation for OCD
• Genetic explanation AO3: Real World Application

  • The identification of the SERT gene as a candidate gene means we can give patients drugs to prevent the gene from mutating e.g SSRIs can prevent the transportation issues of serotonin
  • The genetic explanation has allowed OCD to be explored and treated
• Genetic Explanation AO3: Too many candidate genes

  • As OCD is polygenic it is hard to pin down what genes are causing specific things
  • Each little gene plays a part in the formation of OCD
  • It may be hard to understand, diagnose and treat OCD because of this
• What is the Neural Explanation?

  Relates to the nervous system (e.g brain)

  Consider in terms of neurotransmitter levels and an abnormal circuit
• Neural Explanation: Neurotransmitter levels

  1. Dopamine - Higher levels of dopamine leads to more compulsive behaviours
  2. Serotonin - Responsible for the regulation of mood and lower levels of serotonin are associated with OCD
• Neural Explanation: Abnormal Brain Circuits

  • Orbito-Frontal cortex - involved in our perception of the world when we are worried we send a signal to the thalamus
  • Thalamus - part of the brain that instructs to do a certain behaviour
  • This worry signal is normally supressed by the caudate nucleus in the basal ganglia but if something abnormal occurs the thalamus becomes aware of the signal and send the worry signal back to the orbito-frontal cortex
  • This then causes overthinking leading to obsessions and compulsive thinking
• Neural Explanation: Decision making systems

  • Some forms of OCD have been linked to poor decision making
  • Lateral frontal lobes - responsible for logical thinking and making decisions
  • Parahippocampul gyrus - linked to the processing of unpleasant emotions. Functions abnormally in those with OCD
• Evidence for Neural Explanation

  • Researcher looked at the orbito-frontal cortex in OCD patients on medication and OCD patients not on medication
  • Non-medicated patients showed greater activity in the orbito-frontal cortex and the more activity the more severe their OCD symptoms are
• Neural Explanation AO3: Supporting Evidence

  • Antidepressants that work purely on serotonin are effective in reducing OCD symptoms suggesting serotonin may be involved in OCD
  • OCD symptoms form part of conditions that are known to be biological such as Parkinson’s disease
  • If a biological disorder produces OCD symptoms then we may assume the biological processes underlie OCD
• Neural Explanation AO3: Correlation and Causality

  • There is evidence to show that some neural systems (such as serotonin) do not work normally in people with OCD
  • Brain dysfunction may be causing OCD
  • But this is simply a correlation between neural abnormality and OCD so do not indicate a causal relationship
  • OCD may cause the abnormal brain function or both are influenced by a third factor
• Neural Explanation AO3: Neural mechanisms

  • The serotonin–OCD link may not be unique to OCD
  • Many OCD sufferers also experience depression
  • This depression probably involves disruption to the action of serotonin so leaves us with a logical problem when it comes to serotonin as a possible basis for OCD
  • It could simply be that serotonin activity is disrupted in many people with OCD because they are depressed as well so serotonin may not be relevant to OCD symptoms
• What is a neuron?

  Nerve cells that transmit signals electrically and chemically
• How are signals transmitted within a neuron?

  Electrically
• How are signals transmitted between neurons?

  Chemically
• What is synaptic transmission?


  When neurons send chemical messages across the synapse
• What is a synapse?

  Gap between neurons
• What do SSRIs do?

  • Prevent the process of reuptake to the presynaptic terminal
  • More serotonin is in the synapse so more chance it is carried on as an impulse to other neurons
  • OCD symptoms decrease as serotonin levels increase
• What is Synaptic Transmission?

  
  

  When the impulse reaches the end of the axon, it arrives at the pre synaptic terminal (before the synapse) . These are made of small structures called vesicles (contain neurotransmitters e.g serotonin). The electrical impulse that had travelled down the axon triggers the release of the neurotransmitter which then diffuses down the synapse. The neurotransmitters then attach to the dendrites of the next neuron. The neurotransmitter is then converted back into an electrical impulse
• Combining drug therapy with other treatments

  • Can be used alongside CBT
  • Drugs reduce emotional symptoms so they can respond better to CBT
• Alternatives to SSRIs

  1. Tricyclics - other type of antidepressant and tends to be used when SSRIs do not work as the side effects are more severe
  2. SNRIs - used when SSRIs do not work. Increases levels of serotonin and another neurotransmitter called noradrenaline
• Drug Therapy AO3: Evidence to show effectiveness

  • Clear evidence to show that SSRIs reduce symptom severity and improve the quality of life for people with OCD.
  • Researcher reviewed 17 studies that compared SSRIs to placebos in treating OCD and all 17 studies showed significantly better outcomes for SSRIs than placebo
  • Typically symptoms reduce for around 70% of people taking SSRIs and the remaining 30% can be helped by alternative drugs or combinations of drugs and psychological therapies
  • Drugs appear to be helpful for most people with OCD
• Drug Therapy AO3: Counterpoint to effectiveness

  • There is some evidence to suggest that even if drug treatments are helpful for most people with OCD they may not be the most effective treatments available
  • Systematic review of outcome studies shows that both cognitive and behavioural (exposure) therapies were more effective than SSRIs in the treatment of OCD
  • This means that drugs may not be the optimum treatment for OCD
• Drug Therapy AO3: Cost-effective and non-disruptive

  • Drug treatments are cheap compared to psychological treatments - many tablets or liquid doses can be made in the time it takes to conduct a session of psychological therapy
  • Using drugs to treat OCD is therefore good value for public health systems like the NHS
  • As compared to psychological therapies, SSRIs are also non-disruptive to people’s lives.
  • If you wish you can simply take drugs until your symptoms decline.
  • Psychological therapy involves time spent attending therapy sessions so drugs are popular with many people with OCD
• Drug Therapy AO3: Serious side-effects

  • Although drugs such as SSRIs help most people, a small minority will get no benefit
  • Some people experience side-effects such as indigestion and blurred vision - they are usually temporary but can be quite distressing for people and sometimes are long-lasting
  • Tricyclic side-effects are more common and can be more serious
  • 1 in 100 become aggressive and experience heart-related problems
  • Some people have a reduced quality of life and may stop taking them altogether so the drugs cease to be effective