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Diagnosis and classification of depression

  •  Depression is classified under the DSM-IV-TR as a mood disorder. 
  • Effects a person's emotional state and Includes major depressive disorder - unipolar depression and bipolar disorder - manic depressive psychosis.

Major depressive disorder/ unipolar depression

  •  Characterised by feeling of sadness and a withdrawal from those around us. 
  • Degree of impairment varies from mild to so severe that they can maintain personal hygiene.
  • Can also lead to suicide
  • Symptoms: Cognitive - low self-esteem, suicidal thoughts. Behavioural - loss of appetite, disordered sleep patterns. Emotional - sadness, irritability. Physical - loss of weight, menstrual changes.

Bipolar/ Manic depressive

  • Classified as a psychotic disorder 
  • Major mood swings between severe depression and a state of mania.
  • Syptoms: Cognitive - reckless decisions, expensive ideas. Behavioural - Rapid speech, more talkative. Emotional - Elevated mood, irritable. Physical - little sleep, increased energy.
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Issues of Reliability and Validity

Reliability = the consistency of a measuring instrument e.g. questionnair. Measured in terms of whether two independent assessors give similar diagnosis - inter-rater reliability, or whether tests used to deliver these diagnosis are consistent over time - test retest reliability.

Inter-rater reliability - low leves suggests that is might lead to faulty diagnosis and inappropriate treatment. Lobbestael et al. assessed the inter-rater reliability of Structural Clinical Interview for the assessment of major depressive disorder is a mixed sample of patients and non-patient controls. Results showed moderate agreement with an inter-rater reliability coefficient of 0.66.

Test-Retest Reliability - The Beck Depression Inventory, a 21 item self-repot questionnair used to measure severity of symtoms of depression, thus be able to distinguish between different type of depression. Beck et al. studied the responses of 26 outpaitients tested at two therapy sessions one week apart using the BDI. There was a correlation of of 0.93 indicating a significant level of test-retest reliability. 

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Issues of Reliability and Validity


  • The extent that a diagnosis represents something that is real and distinct from other disorders
  •  The extent that a classification system such as DSM measures what it claims to measure. 
  • A diagnosis cannot be valid if it is not reliable. 

Comorbidity - refers to the extent that two or more conditions co-occur. E.g. research has shown that the presnece of an anxiety disorder is the single biggest clinical risk for development of depression. The expression of anxiety serves as a compounding stressor that leads to major depression, especcially those with genetic vulnerability. 

Content validity - refers to whether the items in a test are represntative of what is being measured. The BDI is considered to be high in centent validity because it was constructed as a result of a consensus among mental health clinicians concerning symptoms found amoung psychiatric patients. 

Concurrent validity - measure of the extent to which a test concurs with already existing standard ways of assessing characteristics. Research has consistently demonstrated concurrent validity between the BDI and other measures of depression - Hamilton depression scale.  

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AO2 of Reliability

  • Reseach support - Keller et al. explored the reliability of the DSM classification system for major deppresion and dysthymia. PPTs were 524 depressed individuals from inpatient, outpatient andcommunity settings at 5 different sites. Each was intervied using DSM criteria and then again 6 monts after. Results showed that inter-rater reliability across different sites was 'fair to good', but 6 months test-retest was 'fair' for dysthymia, but 'poor to fair' for major depression. 
  • Keller et al. sugessted a number of possible reasons why DSM diagnosis of depression may lack reliability. The fact that for major depression to be diagnosed, aminimum of 5/9 symptoms must be present. A one item disagreement makes the difference between the diagnosis of major depressive disorder or a less serious illness. 
  • Zimmerman et al. claimed that DSM-IV criteria for major depressive disorder are unneccessarily lengthy and that doctors have difficulty remembering all 9 symptoms which could then lead to unreliable diagnosis. In a study of 2500 GPs in Australia and New Zealand, found that only 1/4 could list even 5/9 symptoms listes in DSM-IV. Zimmerman developed a breifer definition of major depressive disorder composed of the mood and cognitive symptoms of the DSMV criteria. They found 95% agreement of diagnosis using the simplified and full DSM-IV definitions. 
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AO2 of Validity

  • The diagnosis of depression requires clinicians to defferentiate amoung severa; distinct subtypes. McCullough et al. compared 681 outpatients with various types of depression, they found few differences on a range of clinical, psychosocial and treatment response variables. Suggesting that distinctions between the different subtypes of depression may not be valid.
  • The presence of comorbidity has repeatedly shown to have a negative impact on social and occupational functioning and a poorer response to treatment for patients with depression. Goodwin et al. found that the odds of having suicidal thoughts was 5 times higher in patients with major depression alone, compared to patients with no psychiatric disorder. 
  • Most diagnosis of depression is given by GPs. However, Weel-Baumgarten et al. suggests that diagnosis made by GPs rather than secondary care specialists are made against a background of previous patient knowledge and so could be biased as a result. 
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Psychological explanations of depression - Psychod

Mourning and melancholia

  • when  a loved one is lost there is first a mourning period and then, after a while life returns to normal.
  • For some however, the mourning period never seems to come to an end. They continue to exist in a state permanent melancholia.
  • Freud stated that mourning and melancholia are the same thing - they can both be reactions to loss of a loved one. But mourning is a natural process whereas, melancholia is a patholigical illness.

The pathology of depression 

  • We unconsiously harbour some negative feelings towards those we love. When we loose a loved one these feelings are turned upon ourselves, and in addition we may resent being deserted by them.
  • This is then following by a period of mourning where we recall the memories of the person lost, and gradually seperate ourselves from them. This process may go astray, and we continue a pattern of self-abuse and self-blame because the anger againts the lost person is directed inwards.
  • Thus depression is 'anger turned against oneself'  
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Evaluation of the psychodynamic explanation

Research support

  • Studies have found that many people who have suffered depression describe their parents as affecctionless supporting Freud's concept of 'loss' through withdrawal of affection. Barnes and Prosen found that men who had lost their fathers through death during childhood scored higher on a depression scale than those whose farthers had not died. 
  • Bifulco et al. found evidence that choildren whose mothers died in childhood were more likely than other children to experience depression later on. However, the found that the association could be explained by the lack of care from parents and parent subsitutes following the loss, rather the loss itslef. 


  • Loss only explains a small percentage of cases of depression. It is estimated that only 10% of those who experience ealry lose later become depressed. 
  • Another weakness of the freudian psychoanalytic approach is that the associated therapy - psychoanalysis, has not proved very effective with cases of depression - Comer, 2002. However, this may be because people who are depressed find it diffcult to communicate n the way required by psychoanalysis 
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Cognitive explanation of depression

Aaron Beck's theory of depression - Depressed individuals feel as they do because their thinking is bias towards negative interpretations of the world. Depressed peope have acquired a negative schema, which may be caused by various factors including parental and/or peer rejection and criticisms by teachers. These negative schema are activated when they encounter a new situation that resembles the original conditions in which these schema were learned. Negative schema aresubjective to cognitive biases in thinking. Negative schema and cognitive biases maintain what Beck calls the negative triad, a pessimistic view of the self, world and future. 

Learned helplessness, Seligman - Depression may be learned when a person tries but fails to control unpleasant experiences. Resulting in them acquiring a sense of being unable to exercise control over life, thus becoming depressed. This learned helpnessness then impairs their performance in situations that can be controlled, unable to initiate coping stratergies in times of stress. He also discovered that depressed people thought about unpleasant events in more pessimistic way than non-depressed people. The reformulated helplessness theory suggesst that the depressed person thinks the cause of such events is internal, stable and global. A person prone to ddepression is thus though to show a depressive attributional style, where they attribute bad ouycomes to personal, stable and global character faults. 

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Cognitive explanation of depression

Hopelessness, Abramson et al. - modified the helpessness theory into a still broader hopelessness theory. Explains depression on the basis of pessimistic expectations of the future. Some with a negative attributional style dont become depressed by avoiding traumatic experiences, and so go through these experiences without becoming depressed by avoiding negative thinking. The hopeless person however, expects bad rather good things to happen in important areas of his/ her life and dont belive they have the resources to change that situation.  

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Evaluation of the cognitive explanation - Beck

There is research support for many of Beck's predictions. Lewinsohn et al. assessed teenagers with no existing history of depression and measured their level of negative thinking. A year later those scoring highest for negative thinking were the ones most likely to be diagnosed with depression. This is clear evidence showing negative thinking arises before the depression.However, the fact that there is a link between negative thoughts and depression does not mean that the former caused the latter. Thus we cannot establish causal relationship 

Furthermore, this explanation is too simplistic to fully explain depression thus it is reductionist. It is clear that biology, particularly genes and brain chemistry are involved in depression. Beck's model does not consider this. Similarly he places too great an emphasis on cognitive and doesn't consider the role of factors such as relationships with others.  

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Evaluation of the cognitive explanation - Seligman

There is research support for the thoery of learned helplessness. Hiroto and Seligman showed that college students who were exposed to uncontrollable aversive events were more likely to fail on cognitive tasks. Also a study by Miller and and Seligman found that depressed students performed worst of all on a cognitive task. These finidngs show that having some degree of control and not feeling completely helpless gently improves perfomance especially for those who are depressed. 

A weakness of the learned helplessness theory is that it ignores any references to past events in the patients’ lives such as loss of a loved one. Learned helplessness believes that depression is due to internal cognitions and pessimistic attributions and this is a weakness when compared with the psychodynamic explanation of depression because vital pieces of information about important events in childhood are being ignored and this may mean that the patient is being treated in a way which does not work for them and isn’t effective.

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Evaluation of the cognitive explanation - Abramson

  • Kwon and Laurenceau, provided evidence to support the hopelessness model. PPts were assessed on a weekly basis and found that those with a higher negative attributional style also showed more of the symptoms associated with depression when stressed. It is possible that attributional style is more common in women than men. This is because throughout social development, women are often taught to think in a negative way about themselves. This might explain why many more women suffer from depression than men. Thus there are gender differences when it comes to explaining depression which this theory does not take into account. Therefore, it is gender bias and lack population bias as it canno tbe generalised to the whole population. 
  • Cognitive explanations are associated with successful therapies for depression. Butler and beck reviewed 14 meta-analyses that have investigated the effectiveness of Beck's cognitive therapy and concluded that about 80% of adults benefited from the therapy compared to controls with no treatment. The therapy was more successful than drug therapies and had a lower relapse rate, thus lending the support to the proposition that depression has a cognitive basis 
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Psychological therapies for depression

Cognitive Behavioural therapy (CBT) - developed by Aaron Beck

  • CBT emphasises the role of maladaptive thoughts and beliefs in the origin and maintenance of depression. The aim of CBT is to identify and alter these maladptive cognitions as well as any dysfunctional behaviours that might be contributing to depression.
  • Tended to be relatively brief, 16-20 sessions, and is focused on current problems and dysfuctional thinking. Two main parts of CBT, Thought catching and behavioural activation.

Thought catching - taught how to see the link between their thoughts and the way they feel. As part of hwk may be asked to record any emotion-arousing even, the automatic negative thoughts associated with these events and their realistic thoughts that might challenge these negative thoughts. They are taught to challenge this association by asking themselves questions like 'Where's the evidence that they were talking about me? By challenging these dysfunctional thoughts, and replacing them with more constructive ones, they are trying out new ways of behaving. 

Behavioural activation - Based on the commonsence idea that being active leads to rewards that acts as an antidote to depression. A characteristic of a depressed person is usually that they no longer take part in activities they previously enjoyed. Therapist and client identify potential pleasurable activites and anticipate and deal with any cognitive ostacles. 

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AO2 of CBT


  • Research support - Robinson et al. meta-analysis found that CBT was superior to no-treatment control groups. However, when these control groups were subdivided into waiting list and placebo groups, CBT was not significantly more effectice than the placebo condition at reducing depressive symptoms. 
  • Therapist competence appears to explain a significant amount of variation in CBT outcomes. This is supported by Kuyken and Tsivrikos, as they concluded that as much as 15% of the variance in outcome may be attributable to therapist competence. Therefore, CBT itself is effective and any different outcome could be down to the knowledge of the therapist and not the CBT. 


CBT appears less suitable for people who have higher levels of dysfunctional beliefs that are both rigid and resistant to change. It als appears to be less suitable in situations where high levels of stress in the individual reflect realistic stressors in the person's life that therapy cannot resolve. 

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A02 of CBT


CBT appears less suitable for people who have higher levels of dysfunctional beliefs that are both rigid and resistant to change. It als appears to be less suitable in situations where high levels of stress in the individual reflect realistic stressors in the person's life that therapy cannot resolve. 

CBT in depressed adolescents - March et al. enrolled 327 adolescents aged 12-17, who were diagnosed with major depression. They were randomly assigned to either fluoxetine alone, CBT alone or fluoxetine combined with CBT. 12 weeks later, 62% responded positively to the drug treament alone, 48% to CBT alone and 73% to a combination of both. 36 weeks later, 81% responded positively to either the drug or CBT alone, and 86% to the combination treatment. Thus suggesting that CBT is more effecive in adolescents when compared with a drug treamnet, therefore CBT is not as effective alone. However, a further analysis found that CBT had significantly reduced suicidal thoughts and behaviours. When patients began study 30% expressed thought about suicide. At the end of study, this dropped to under 15% for those on the drug treatment, compared to 6% for those who had CBT. 

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Psychodynamic interpersonal therapy (PIT) (Robert

Hobson believed that the symptoms of depression arise from disturbances in interprersonal relationships. These disturbances can only be explored and modified effectiveky from within another relationship - therapeutic one, quality of relationship is thus crucial. Components of PIT - model has 7 interlinking components:

  • Exploratory rationale - interpersonal difficulties in the individual's life are identified, and therapist tries to find a rationale for individual that links their current symptoms with these difficulties. 
  • Shared understanding - therapist tries to understand what the individual is really experiencing/ feelin, by saying e.g. 'This is what i am hearing you say. Have I got it right?' 
  • Staying with feelings - instead of talking about feelings in an abstract way, an attempt is made to recreate them in the therapeutic environment.
  • Focus on difficult feelings - individual may express an emotion of which they are unaware, or may not display an appropriate emotion e.g. appear calm when discussing something of great emotional significane.
  • Gaining insight - therapist points out patterns in different types of relationship.
  • Sequencing of interventions - different aspects of the model must be used in a coherent manner.
  • Change - therapist acknowledges and encourages changes made during therapy. 
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AO2 of PIT


Research support - Plaey et al. investigate dthe effectiveness of PIT in a routine clinical practise setting. 62 patients recieved a course of PIT over 52-month period. Outcomes were assessed using many meausures, e.g. Beck's Depression Inventory. Found significant differences in scores on the BDI in pre- and post-treament phases. Clinically significant change was achieved by 34% of clients, measured by scores on BDI. Although these results were less favourable than those obtained during clinical trials, they are roughly equivalent to changes in depressive symptoms reported with other treatments -CBT. Thus showing that PIT can be an effective treatment for depression in routine clinical settings. However, they acknowlege that changes in significant life-events were not monitored during study, therefore any observed clinical gains could not be attributed solely  to the theraputic intervention.

The collaborative psychotherapy project (CCP), found that PIT and CBT were equally effective in reducing the severity of depression, measured by BDI. However, 12 months later, those treated with PIT or CBT showed a tendency for symptoms to recur, thus limitng its long term effectiveness.      

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A02 of PIT


NHS psychotherapy patients were randomly allocated to recieve 12 weeks of PIT ot to remain as waiting list controls for that period. 54 patients entered the study, of whom 33 completed. Significant improvement was observed in patients who completed therapy, suggesting that even brief treatment by inexperienced therapists can be effective in alleviating the symptoms of depression. However, high attrition rates were found between waiting list and completion of therapy. 

The problem of attrition - Hunt and Andrews examined 5meta-analyses and found the median drop-out rate was 8%. If PPTs drop out because they feel therapy is not helping, then the outcomes for the remaining PPTs will appear artificially positive. The remaining PPTs are more likely to be highly motivated and to show greater improvement also biases results, as those remaining are probably doing less well. 

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