Intro/ Diagnosis & Classification
Depression is an affective mood disorder and it is the most common form of mental disorder. The DSM distinguishes between major depression (unipolar) and bi-polar. 10% of men and 20% of women become clininically depressed at some point in their lives. 90% of them suffer from unipolar.
Clinical depression is where everday functioning is impaired.
Diagnosis & Classification
Clinical characteristics of major depressive disorder:
For a diagnosis of depression, these symptoms should be present all or most of the time and should persist for longer than 2 weeks:
- sad, depressed mood = as indicated by either subject report (feeling sad or empty), or observation made by others (e.g. appears tearful).
- loss of interest/ pleasure in usual activities= as indicated by either subjective account or observation made by others.
- difficulties in sleeping = some patients have a desire to sleep all the time.
- poor appetite and weight loss or increased appetite & weight gain= e.g. significant weight loss when not dieting.
- difficulity in concentrating= slowed thinking/ indecisiveness
- recurrent thoughts of death or suicide
- loss of energy
- negative self concept, feelings of worthlessness and guilt
- shift in activity level- lethargic or agitated- observable by others
The formal diagnosis of Depression requires at least 5 out of 9 to be present.
Reliability & Validity issues
Reliability- refers to the consistency of a measuring intrument e.g. a questionnaire/ scale, to assess for example, the severity of depressive symptoms.
Inter-rater reliability-> is about assessing whether two indepedent clinicians give similar diagnoses. Low levels of inter-rater reliability related to a classification procedure suggest that it might lead to faulty diagnosis/ inappropriate treatment.
Test-retest reliability -> is about whether tests used to deliver these diagnoses are consitent over time. The DSM V (5) has emphasised the importance of test-retest reliability & has this as one of its main goals. Current measurement scales such as the Beck Depression Inventory (BDI) have been assessed for their test-retest reliability.
I- there is research evidence for the DSM diagnosis of depression.
J- Research on the reliability of diagnoses using the DSM classification system suggests that inter-rater reliability is 'fair to good' whereas test-retest is 'fair' at best. Zanarini also came to the same conclusion, who although finding an inter-rater reliability correlation of .80 for major depressive disorder, found a test-retest correlation of just .61 with one week between diagnosis sessions.
E- This lack of reliability is an issue as it could lead to the wrong type of treatment being given to a sufferer of depression or misdiagnosis.
Reliability- 2nd A02
I- Keller suggests a number of possible reasons why the DSM diagnosis of depression might lack reliability.
J- These include the fact that for major depression to be diagnosed, 5 out of 9 symptoms must be present. When the severity of the disorder means that it's on the diagnostic threshold, a one item disagreement makes the difference on the diagnosis of the disorder.
E- Therefore suggesting that the guidelines set out by the DSM may need to be altered to increase reliability. Also, if a person is therefore wronly diagnosed with depression this can have a big impact on their life e.g. labelling.
Reliability- 3rd AO2
I- There is evidence to support simplifying the diagnosis of depression.
J- Zimmerman et al claim that the DSM criteria for major depression disorders are unnecessarily lengthy and that doctors frequently have difficulty recalling all 9 syymptoms; as shown by Krupinski and Tiller's study on 2,500 GPs. Zimmerman then developed a briefer definition of major depressive disorder.
E- This suggests that the DSM method is too complicated, leading to incorrect diagnoses and so lacking reliability.
Validity-> refers to the extent that a classification system e.g. DSM, measures what it claims to measure.
Comorbidity-> is an important issue for the validity of diagnosis of mental illness, It refers to the extent that two or more conditions co-occur. E.g. research has shown that the presence of an anxiety disorder is the biggest clinical risk for the development of depression.
Content validity-> refers to whether the items in a test are representative of what is being measured e.g. the BDI is considered to be high in content validity as it was constructed as a result of a consensus among mental health clinicians.
Concurrent validity-> is a measure of the extent to which a test concurs (agrees) with already existing standard ways of assessing the characteristic in question.
I- the diagnosis of depression requires clinicians to differentiate between several distinct subtypes of this disorder.
J- However, when McCullough compared 681 outpatients with various types of depression, they found few differences on a range of clinical, psychosocial and treatment response variables.
E- This suggests that distinctions between different subtypes of depressuin may not be valid.
Validity- 2nd A02
I- GP diagnoses of depression may lack validity
J- For most people, a diagnosis of depression is given by their local GP. However Van Weel-Baumgarten et al suggests that diagnoses made by GPs, rather than seconday care specialists are made against a background of previous patient knowledge and so could be biased.
E- This suggests that to get a more valid diagnosis, a secondary care specialist may have to diagnose the depression rather than the GP.
A03- Cultural differences
- There are cultural differences in the diagnosis of depression.
- members of ethnic minority groups are less likely than middle class white people to seek professional help.
- various explanations have been offered fo this, including the stigma attached to mental illness in some cultures. Therefore cultural differences may impact on whether an individual gets treatment or not.