The Four D’s of Diagnosis
Deviance – Clinicians look at the extent to which the behaviour is ‘rare’ in society
Dysfunction – If the behaviour is significantly interfering with a person’s life, although a person may
have a MHD yet it may not be having an everyday impact on their behaviour
Distress – The extent to which the behaviour is causing upset to the person, this should be treated in
isolation to the other four features
Danger – If the person’s behaviour causes danger to themselves or others, if considerable danger is
caused, then intervention may be needed
Some other researchers view ‘Duration’ as the fifth D, as it is problematic if it lasts for a long period of
time
Evaluation
- There are many issues with using this method as a decision is made by the individual on the level of
abnormality, there is also subjectivity in the interpretation of people’s experiences, clinicians must take
into consideration how the person is coping with the behaviour discussed
- There are also issues with reliability when considering whether the behaviour requires further
diagnosis, clinicians should explore all of the issues and make sure that everybody is measured in a
standardised way
- There are standard tests to assess symptoms of many disorders and these should be used rather than
making a person judgement, some of the problematic behaviours are not actually that rare
- You can also end up with labels for people with MHDs which could worsen their situation
, Classification systems
International Classification of Diseases (ICD) – ICD10 section F contains MHDs, while other
sections contain physiological disorders, further numbers then represent what type of disorder it is, as
well as how much pain there is (F20 is sz), the ICD provides a basis on how clinicians can reach a
decision from clinical interviews
Diagnostic & statistical manual of mental disorders – DSM V – Groups disorders into families,
although just covers MHDs
DSM IV-TR – Contains 5 axes of diagnosis, sz is in axis 1 which covers major clinical syndromes &
MHDs, axis 2 described symptoms related to personality disorders.
There are cultural differences between European ICD & American DSM
Reliability – The extent which clinicians agree on the same diagnosis for the same patient. Brown et al.
found a high level of agreement for most DSM-IV categories when patients underwent 2 clinical
interviews, although Reiger found reliability of sz diagnosis was 0.46, the diagnosis of PTSD/binge
eating was better. For ICD, Nicholls found a 36% agreement for eating disorders, although Jakobsen
found ICD gave reliable sz diagnosis with predictive value of 87%. Patient & clinician factors can affect
reliability
Validity – Wrong diagnoses can lead to the wrong treatment, clinicians can establish validity through:
concurrent validity (comparing diagnostic tools), aetiological validity (comparing known causes of
, Schizophrenia (sz)
Positive symptoms add to the experience of the patient:
- Delusions (grandiose, persecutory and referential)
- Hallucinations (seeing and hearing things which aren’t there)
- Disorganised thinking and/or speech
- Abnormal motor behaviours (including catatonia, can also include dressing bizarrely or fidgeting)
Negative symptoms subtract from normal behaviour these include:
- Avolition (lack of motivation to complete usual, self-motivated activities)
- Alogia (reduced speech)
- Anhedonia (decreased ability to find pleasure in everyday life)
Prevalence and onset:
- Likelihood of developing sz is between 0.3 & 0.7%
- Episodes seem to appear between late adolescence and mid-thirties, peak onset in males is early-
mid 20s and for females is late 20s
Prognosis:
- Approx. 20% of those with sz will respond well to treatment, with some regaining a good quality of
life, however a large number will remain chronically ill
- Doctors have not found a way to accurately predict prognosis after diagnosis
Deviance – Clinicians look at the extent to which the behaviour is ‘rare’ in society
Dysfunction – If the behaviour is significantly interfering with a person’s life, although a person may
have a MHD yet it may not be having an everyday impact on their behaviour
Distress – The extent to which the behaviour is causing upset to the person, this should be treated in
isolation to the other four features
Danger – If the person’s behaviour causes danger to themselves or others, if considerable danger is
caused, then intervention may be needed
Some other researchers view ‘Duration’ as the fifth D, as it is problematic if it lasts for a long period of
time
Evaluation
- There are many issues with using this method as a decision is made by the individual on the level of
abnormality, there is also subjectivity in the interpretation of people’s experiences, clinicians must take
into consideration how the person is coping with the behaviour discussed
- There are also issues with reliability when considering whether the behaviour requires further
diagnosis, clinicians should explore all of the issues and make sure that everybody is measured in a
standardised way
- There are standard tests to assess symptoms of many disorders and these should be used rather than
making a person judgement, some of the problematic behaviours are not actually that rare
- You can also end up with labels for people with MHDs which could worsen their situation
, Classification systems
International Classification of Diseases (ICD) – ICD10 section F contains MHDs, while other
sections contain physiological disorders, further numbers then represent what type of disorder it is, as
well as how much pain there is (F20 is sz), the ICD provides a basis on how clinicians can reach a
decision from clinical interviews
Diagnostic & statistical manual of mental disorders – DSM V – Groups disorders into families,
although just covers MHDs
DSM IV-TR – Contains 5 axes of diagnosis, sz is in axis 1 which covers major clinical syndromes &
MHDs, axis 2 described symptoms related to personality disorders.
There are cultural differences between European ICD & American DSM
Reliability – The extent which clinicians agree on the same diagnosis for the same patient. Brown et al.
found a high level of agreement for most DSM-IV categories when patients underwent 2 clinical
interviews, although Reiger found reliability of sz diagnosis was 0.46, the diagnosis of PTSD/binge
eating was better. For ICD, Nicholls found a 36% agreement for eating disorders, although Jakobsen
found ICD gave reliable sz diagnosis with predictive value of 87%. Patient & clinician factors can affect
reliability
Validity – Wrong diagnoses can lead to the wrong treatment, clinicians can establish validity through:
concurrent validity (comparing diagnostic tools), aetiological validity (comparing known causes of
, Schizophrenia (sz)
Positive symptoms add to the experience of the patient:
- Delusions (grandiose, persecutory and referential)
- Hallucinations (seeing and hearing things which aren’t there)
- Disorganised thinking and/or speech
- Abnormal motor behaviours (including catatonia, can also include dressing bizarrely or fidgeting)
Negative symptoms subtract from normal behaviour these include:
- Avolition (lack of motivation to complete usual, self-motivated activities)
- Alogia (reduced speech)
- Anhedonia (decreased ability to find pleasure in everyday life)
Prevalence and onset:
- Likelihood of developing sz is between 0.3 & 0.7%
- Episodes seem to appear between late adolescence and mid-thirties, peak onset in males is early-
mid 20s and for females is late 20s
Prognosis:
- Approx. 20% of those with sz will respond well to treatment, with some regaining a good quality of
life, however a large number will remain chronically ill
- Doctors have not found a way to accurately predict prognosis after diagnosis
