Diagnosis and classification of depression

DSM 5 (diagnostic statistical manual IV)

Used for diagnosis of D. This is usually used by practioners who arent completely qulified in disorders such as D and the DSM5 is persistant most of the time.

Diagnosis

According to the DSM5 D is a mood disorder with 9 sympotms seperated into 4 domains (affective,cognitive,behavioural, physical). In order for an individual to be diagnosised with D there must be 5 of the 9 symptoms lasting for 2 weeks and 1 of the 5 symptoms MUST be a sad depressed mood or loss of interest or pleasure in usual activites. The other symptoms may be: suicidial ideation, insomina (no sleep or opposite hypersomina), shift in activity level, negative selfconcept/ feeling of worthlessness or difficulties in concentrating.

Beck Depression inventory (BDI)

A 21 closed questionnaire with a likert scale used to measure the severity of D. The higher the score the more severe the level of depression. 

reliability = research by KELLER etal was followed up by ZANARINI et al who conclcuded that although an inter-rater relaibility correlation was of 0.80 for major depressive disorder, test-retest found a correlation of jsut 0.61 with one week ebtween diagnosis sessions.

reliability= Keller et al conducted a mulit site study using 524 depressed in patients and out patients at 5 different sites. Each person was interviewed using the DSM criteria and were then interviewed 6 months later to establist test-retest reliability. the found a 'fair to good' inter-rater reliability scores across the sites, byut after 6months test-retest 'fair' for dysthymia but 'poor to faor' for major depression.

validity = comorbility is an issue with the validity of mental illness, refering to th extent at whcih 2 or more conditions co-occure. for example, D and aneroxia ahve very similiar characteristics so a practionor may diagnose someone with aneroixa when really they have D which could have dextromental effects

Validity = content validity is whether the items in the test are measuring what they intent to measure. The BDI has a high content validity because it was constructed as a result of a consensus among mental health clinicians concerning symtoms found among psychiatric patients.

Validity = this has good concurrent validity as it is consistent with other existing tests. reserach by beck consistently shows concurrent validity between BDI and other measures like the hamiliton depression scale.