Presentation on theme: "Classification and explanation of obsessive compulsive disorder (OCD)"— Presentation transcript:
1Classification and explanation of obsessive compulsive disorder (OCD) Learning objectivesDescribe the clinical characteristics of OCDDescribe and evaluate biological & psychological explanations of OCD
2Statistics for OCD Prevalence – thought to affect 1-3% of the pop. OCD occurs in M’s and F’s equally, onset normally in adolescence or adulthood, but can begin in childhood.For some it begins suddenly following some traumatic experience but for about 30% there are no clear triggers.Prognosis – 30% show significant improvement following some form of therapy, 40% show moderate improvement, 30% show no improvement.30% will also have depression and be at risk of suicide
3Clinical characteristics OCD involves, obsessions and compulsions.
4Obsessions Recurrent, intrusive thoughts, ideas, images or impulses. Obsessions often have sexual, blasphemous or aggressive themes.The individual tries to deal with these intrusive thoughts either by ignoring them or neutralising with some other thought or action.
5CompulsionsCompulsions are irresistible, repetitive physical or mental actions that people feel compelled to carry out.People with OCD recognise that these actions are unreasonable and excessive but cannot stop themselves.They believe that carrying out the ritual will prevent something terrible happening.Their performance is never directly pleasurable but can relieve some of the tension and anxiety.The most common examples are compulsive checking and washing.
6Consequences of disorder Frequently has negative effects on family and social relationships.This in turn can cause more anxiety and depression for the sufferer.Also good to note that the intrusive thoughts that OCD sufferers experience of the type that suggests they are going to do some harm to themselves or others are rarely ever actually carried out.
7Diagnostic Criteria1.Either obsessions and/or compulsions are present on most days for a period of at least 2 weeks.Obsessions or compulsions share the following features (all must be present)They originate in the mind of the person. They are repetitive and unpleasant. The patient tries to resist them. Experiencing the obsessive thought or carrying out the compulsive act is not in itself pleasurable.2. the obsessions and/or compulsions cause distress or interfere with everyday functioning.3. the obsessions and/or compulsions are not the result of other mental disorders or mood disorders.
8Issues surrounding classification and diagnosis OCD often occurs with depression and it is unclear which is the primary and which the secondary disorder.OCD symptoms can resemble schizophrenia when they involve particularly bizarre obsessional thoughts.Providing the other symptoms are carefully assessed though it is usually easily distinguishable.OCD is not confined to western cultures, and where ever it occurs the symptoms are very similar.
9Single disorder?There has been a tendency to see OCD as a single category – however Jakes 1996 suggested that there are sub-groups, which are mainly checking or mainly cleaning in nature and that these might have different origins and therefore respond better to different treatments.
10Biological Explanations Genetics – thought to run in families.However Black et al 1992 – only found 2.5% of relatives of OCD sufferers had the disorder which is no greater than the general pop prevalence rate.Pauls et al 1995 – found a higher rate if they included relatives that had some of the symptoms but not full blown OCD.Billet et al 1998 – review of 14 twin studies found that out of 54 out of 80(67.5%)MZ twins were concordant compared to 9 out of 24 (37.5%)DZ twins.
11What might be inherited? How genetics might contribute to the disorder could be in terms of brain structure which in turn influences some ones ability to perform mental tasks.Recent research has implicated a gene called ‘sapap3’, which is expressed in part of the brain called the straitum, that controls planning & initiating appropriate action.Feng et al 2007 found that mice lacking this gene show high levels of anxiety and show excessive amounts of time on grooming. When given extra sapap3 protein, the abnormal behaviour disappeared.
12Commentary of genetic link Not a lot of research has been done looking specifically at OCD.Even if genes do play a role it is not clear exactly what is passed on.Gene research is relatively new and has not yet been replicated.It is difficult to generalise from species like mice to humans.However it is a promising area and might be able to tell us more about the origins of OCD in the future.
13Biochemical FactorsA deficiency in the neurotransmitter serotonin could be a causal factor.In OCD it is thought that certain receptors block serotonin from entering the cell.The main evidence for this is that SSRI’s provide some relief of symptoms.SSRI’s work by preventing nerve cells that have just released serotonin from reabsorbing it making it more available in the synapses for other neurons. (will look at this again when we look at treatments)
14Commentary on biochemical explanation for OCD SSRI’s do provide some relief but it takes about weeks for most OCD sufferers to report improvement, it is known that long-term use of SSRI’s affect serotonin function but do not increase availability.Research by Insel 1991 showed 50% improvement only, with some sufferers showing no improvement at all.So – although serotonin is implicated, serotonin dysfunction alone cannot explain OCD.
15Neuroanatomical factors (1) One suggestion is that there is some abnormality in the ‘Basal Ganglia’The Basal Ganglia is part of the Reptilian Brain – the oldest part of the brain which is primarily responsible for ‘action selection’See Handout and Go to -For extra coverage of the role of the Basal Ganglia.
16Basal Ganglia cont.,OCD is often found in people suffering from Parkinson’s disease, Tourettes syndrome and Huntington’s chorea, all of which are disorders in which the basal ganglia is implicated. (Wise & Rapoport 1989)basal ganglia damage resulting from head injury can lead to OCD. (Max et al 1994)Surgery that disconnects the basal ganglia from the frontal cortex can reduce severe OCD symptoms. (Rapoport et al 1994)
17However Results using neuro-imaging techniques have been inconclusive. basal ganglia impairment has not always been found in OCD sufferers when compared to controls. (Aylward et al 1996)
18Neuroanatomical factors (2) Another structure that might underpin OCD is a circuit involving 3 anatomical brain regions.Called the ‘cortical-striatal circuit’The orbital-frontal cortex (OFC)The caudate nucleusThe thalamus.
19The Loop!The OFC is the part of the brain that knows if something is wrong.E.g. the OFC registers that there is dirt nearby, it sends a signal to the thalamus which directs signals from many parts of the brain to places that can interpret them, in this case back to the OFC.These nerve cells connections form a loop in the brain.
20What happens normallyWorry detected by the OFC and message sent to the thalamusCaudate nucleus intercepts message and reduces the strength of the original messageThalamus pick up message and then sends message back to the OFCOFC then interprets the message and responds with appropriate behaviour to deal with ‘worry’
21What goes wrong?The caudate nucleus lies between the OFC and the thalamus and regulates the messages between them.When the thalamus receives a worry signal it becomes excited and sends a strong signal back through the loop to the OFC which interprets them.Normally the caudate nucleus acts like a brake, and suppresses the original ‘worry’ signal the OFC sent to the thalamus.If this is faulty then the ‘strong’ message gets sent through and back again with no reduction of intensity, this leads to the thalamus becoming hyperactive.When the OFC receives these very strong messages it responds by increasing compulsive behaviour and anxiety.
22ActivityDraw a diagram (like the one on slide 20) to demonstrate the loop for someone with a damaged caudate nucleus as previously described.
23Support for this ideaOne of the mode of operation for SSRI’s is to increase stimulation of serotonin receptors in the OFC and in doing this it inhibits its over activity.Menzies et al (2007) Used MRI scans and compared OCD sufferers and controls they found that they had lower amounts of grey matter in the OFC and the right frontal regions of the brain.Both areas are known to have a regulatory role.Read and take notes of full study on page 380.
24Commentary on biological explanations for OCD Biological explanations are promising but cannot yet offer a complete explanation.Biological explanations get most support from the fact that drug that increase serotonin appears to work.However – it does not work for everyone, and symptoms recur once medication is stopped.It is also risky to infer the cause of a disorder from a therapeutic effect. (see treatment aetiology fallacy – pg 381)There is no evidence to show that serotonin levels are any different in OCD sufferers than controls (Pigott et al 1996)One of the major challenges for biological explanations is that psychological treatments have good success rates with OCD and yet involve no physical intervention!
25ActivityProduce an A3 summary sheet for the biological explanation for Anxiety disorders.
27Psychological explanations - psychodynamic Freud believed that OCD was the consequence of problems with toilet training.He believed that we develop through a series of psycho-sexual stages.At each stage there are conflicts to be resolved.During the Anal stage the conflict is about
28Conflict in the Anal Stage The major conflict at this stage is toilet training. The child has to learn to control his or her bodily functions.Developing this control leads to a sense of accomplishment and independence.success at this stage depends on how parents approach toilet training.Parents who praise and reward for using the toilet will help children feel capable and productive.If parents take an approach that is too lenient, anal-expulsive personality could develop in which the individual has a messy, wasteful, or destructive personality.If parents' punish, ridicule, or shame a child for accidents it will lead to negative outcomes. This over strict toilet training will lead to an anal-retentive personality i.e. the individual is stringent, orderly, rigid, and obsessive.
29Repressed AngerDuring the Anal stage the infant may become angry when their parents try to make them use the toilet.Because they do not have the power to do anything about it they repress their anger and later in life they displace this anger onto more acceptable thoughts and impulses.However if these thoughts intrude into consciousness, they appear alien and frightening.This anxiety is managed by carrying out compulsive rituals to cancel out the undesirable impulse.
30Commentary on psychodynamic explanations Little evidence to support theory.Milby & Weber 1991 found no greater incidence of parent-child toilet training conflicts in people with OCD compared to controls.Clinical data shows that some people who go on to develop OCD do have anal personality traits before the onset of the disorder.However – many people with anal personality traits do not develop OCD and equally not all OCD sufferers show these personality traits.
31Psychological explanations – Behavioural Theory Behaviourists concentrate on explaining the compulsions rather than the obsessions.One suggestion is that in a fearful situation people might by chance act in a certain way, such as washing hands, when the threat disappears the individual comes to associate the action with the removal of the threat (classical conditioning)They then repeat the action in a similar situation because they have learnt that this reduces anxiety (Operant conditioning)However this also serves to maintain longer term anxiety because they never learn that no harm will occur if they do not perform the action.
32Commentary of behavioural explanation for OCD This theory has led to reasonably effective therapy, exposure and response prevention (ERP) will look at this later.However the theory does not explain the obsessive thoughts and why the compulsions start in the first place.At most it simply explains why/how the compulsive behaviours are maintained.
33Cognitive-behavioural theory of OCD Rachman and Hodgson 1980 point out that we all experience intrusive thoughts at times and usually we’re able to dismiss them fairly easily or distract ourselves, the difference is that someone suffering from OCD cannot do this.They add that when people feel anxious, stressed or depressed, they find it harder to dismiss such intrusive thoughts.Evidence shows that people with OCD often do also suffer from depression.Rachman 1977 also suggested that obsessions are caused when an individual misinterprets the significance of the intrusive thoughts.
34ExampleRachman gives an example of a young man who has recurrent thoughts and images about causing physical harm to the young child of a friend.Instead of being able to dismiss this the man interprets it as revealing him to be a potential murderer and a worthless person.Beliefs such as these lead to further anxiety and the individual tries to reduce by suppressing the thoughts, which seems to make the intrusive thoughts even worse.
35Try it for yourself!! Try to follow this instruction: In the next 5 minutes Do not under any circumstance think about Polar Bears
36Commentary on CBT theory for OCD Salkovskis & Kirk 1997 – asked people with OCD to keep a daily diary to record their obsessional thoughts.They were instructed to try to suppress these thoughts on some days and on others to just let them occur.They found that on the days they had been asked to try to suppress the thoughts the number of intrusive thoughts was significantly higher compared to the other days.
37Commentary cont.,Since it is very hard for OCD sufferers to suppress these thoughts they engage instead in a series of ‘safety behaviours’ to try to reduce the possible negative outcomes of their impulses.Cleaning/checking ritualsNeutralising the thought by substituting a repeated phrase (e.g. Marilyn saying no-no-no-no over and over)Seeking reassurance from others.These strategies provide some relief but as with simple learning theory the individual never learns that no harm will occur if they do not carry out the rituals.
38Plenary / Assessment of Learning What are the clinical characteristics of OCD?What evidence is there that OCD might have some biological origins.Summarise the psychodynamic explanation.Summarise the behavioural explanation.Summarise the cognitive explanation.Which explanation do you find the most convincing and why?