Session 3: Diagnosis of mental disorders
Discuss reliability and validity of diagnosis
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Diagnosis within psychology means
identifying and classifying abnormal
behaviour on the basis of symptoms, the
patient’s self reports, observations, clinical
tests or other factors such as information
from relatives
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To identify groups of similar sufferers so that
psychiatrists and psychologists may develop
explanations and treatment methods to help
those groups
Billing purposes. The government and many
insurance companies require a diagnosis for
payment
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Diagnosis of Mental Disorders is difficult
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Issue of drawing the line between what is seen as normal
behavior and what is seen as or ‘abnormal’ behavior.
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Because it is difficult to define it is also difficult to diagnose.
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Reliability of diagnosis: Will different diagnosticians
using the same classification system arrive at the same
diagnosis?
Validity of diagnosis: Does the person diagnosed have
real symptoms with a real underlying cause? (the illness
is not socially constructed, the person is not faking)
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Deviation from social norms
Deviation from ideal mental health
Statistical infrequency
Failure to function adequately
Mental illness criteria
Those making diagnoses use a combination of
these factors when making their diagnosis of
mental disorders. They use standardized systems
which aim to increase validity and reliability of
diagnosis.
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While a doctor looks for signs of disease using Xrays, scanners, or blood tests, as well as
observable symptoms, the psychiatrist will often
have to rely primarily on the patient’s subjective
description of the problem.
This reduces validity and reliability.
How are mental disorders diagnosed?
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Clinical interview is most commonly used means of assessment
Interview usually involves face to face contact with clinician
Although format may vary, most interviews cover these topics:
 Identifying data: contact details, marital status, age, gender, employment,
religion, employment
 Description of presenting problems: What are troubling
behaviours/feelings/thoughts? How do they affect functioning? When did they
begin?
 Psychosocial history: Information describing client’s history: educational, social,
early family relationships etc
 Psychiatric history: History of psychiatric illness/past treatment
 Medical problems/medication: Description of medical problems/medication. May
link to psychological problems
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Today the clinician—often a psychiatrist—uses a standardised
diagnostic system e.g. DSM-IV, ICD
Issues with clinical interviews
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Kleinmutz (1967) has noted that there are limitations to
this interview process that can affect reliability/validity of
diagnosis:
◦ Information exchange may be blocked if either the patient or the
clinician fails to respect the other, or if the other is not feeling well.
(e.g. what if the patient is mute?)
◦ Intense anxiety or preoccupation on the part of the patient may affect
the process.
◦ A clinician’s unique style, degree of experience, and the theoretical
orientation (e.g. Cognitive or biological psych) will definitely affect the
interview.
How are mental disorders diagnosed?
In addition to interviews, other methods can be used to assist with
diagnosis.
These include:
 direct observation of the individual’s behaviour
 brain-scanning techniques such as fMRI and PET (especially in cases
such as schizophrenia or Alzheimer’s disease)
 psychological testing, including personality tests (e.g. MMPI-2) and
IQ tests (e.g. WAIS-R).
DSM
Diagnostic and Statistical Manual of Mental Disorders
ICD
International Classification of Diseases
These classification systems are constantly being
revised, mental disorders are added, deleted and
reorganized in the light of new research evidence
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The two major classification systems used by western psychiatrists today,
the DSM DSM-IV –TR Diagnostic and Statistical Manual of Mental Disorders,
(American Psychiatric Association, 1994) and the lCD-10 International
Classification of Diseases, (WHO, 1992)
Based largely on abnormal experiences and beliefs reported by patients, as
well as agreement among a number of professionals as to what criteria
should be used.
This can explain why the criteria change in revisions of the diagnostic
manuals, for example homosexuality was included in earlier versions of the
DSM.
Some argue that the difficulties met in trying to identify haracteristics of
“abnormality” reflect the fact that abnormal psychology is a social
construction that has evolved over time without prescriptive and regulating
definitions. It is also argued by some that the DSM-IV is gender and
culturally biased. This effects the reliability of diagnosis
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While the main purpose of the ICD is the classification of
disorders, the DSM classification system has the additional
purpose of assisting clinicians to diagnose a persons problem
as a particular disorder.
Diagnosis is important because it determines treatment.
The DSM-I was published in 1952. The DSM-II and DSM-III
caused a lot of debate amongst clinicians because there was a
lack of consensus of the precise listing of disorders (Davison
et al. 2004).
The DSM-IV was published in 1994 and the DSM-IV-TR (text
revision) was published in June 2000, and the long awaited
DSM-V is coming out this year (2013).
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The classification system used in the United
States
Lists more than 250 mental disorders
The diagnosis of one individual is based on
five dimensions
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Axis I: The major diagnostic classification, e.g.
major depressive disorder, anorexia
Axis II: Related to developmental and personality
disorders (e.g. autism, anti-social personality)
Axis III: Physical and medical conditions that may
worsen the disorder (e.g. brain injury, drug abuse,
viruses)
Axis IV: Psychosocial stressors, all stressful events
that may be relevant to the disorder (e.g. poverty,
divorce, loss of job)
Axis V: Global assessment of functioning. Rates the
highest level of social, occupational and
psychological functioning on a scale of 1
(persistent danger) and 90 (good in all areas)
currently and during the last year
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Read through the descriptions of each party
guest
Using some of the descriptors from Axis II
(personality disorders) try to identify which
personality disorder each guest has
Work individually
We will compare answers when you have
finished
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Watch the video critique of the DSM
What are the issues with validity and
reliability?
Remember you also need to think critically
about the source itself as well!
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The current edition – the ICD-10 was published in 1992 by the
WHO – the ICD-11 is expected to be published in 2015
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Mental disorders where included in the ICD in 1952 (ICD-6)
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Main purpose of ICD is to make it easier to report health
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statistics.
Enables universal agreement on the definitions of specific
disorders or sets of syndromes – without these it would be
very difficult for clinicians and researchers in different
countries to communicate with each other.
The ICD identifies 11 general categories of mental disorders.
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Use of the DSM and the ICD increase the validity
& reliability of diagnosis
Diagnostic systems provide a template which the
clinician can use to compare information about
disorders to the condition of a particular client.
In this way, clinicians can use the same models
for diagnosis.
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The difficulty arises over whether classification can indeed
be made effectively using classification systems.
For a classification system to be reliable, it should be
possible for different clinicians, using the same system, to
arrive at the same diagnosis for the same individual. (this is
known as inter rater reliability)
Although diagnostic systems now use more standardised
assessment techniques and more specific diagnostic
criteria, the classification systems are far from perfect.
Mitchel et al. (2009)
 Carried out a meta-analysis of 41 clinical trials with
(50,000 patients) that had used semi- structured
interviews to assess depression
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General Practitioners (GPs) had an 80% reliability in
identifying healthy individuals and 50% reliability in the
diagnosis of depression.
GPs had problems making an accurate diagnosis of
depression.
Cooper et. al. (1972)
 When shown the same video clips, New York
psychiatrists were twice as likely to
diagnose schizophrenia than London
psychiatrists.
 London psychiatrists were twice as likely to
diagnose mania or depression than New
York psychiatrists
Spitzer and Williams (1985)
 Showed that psychiatrists only agree in diagnoses
about 50% of the time.
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The labelling of patients with certain disorders may affect the
practitioners perceptions of them (compare with researcher bias),
patients may act the label that has been given to them (self fulfilling
prophecy). The label itself may simplify a problem that is highly
complex
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People may fake mental illness in order to avoid punishment (The
insanity defense)
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There are significant individual differences for mental disorders. An
individual may have multiple mental disorders
Temerline (1970)
 Clinically trained psychiatrists were influenced
in their diagnosis by hearing the opinion of a
respected authority (expert influence)
 Participants watched a video-taped interview of
a healthy individual.
 The authority claimed, even though the person
only seemed to be neurotic (distress where
behaviour is not outside social norms, patient
has not lost touch with reality) he was actually
psychotic (behaviour is outside social norms,
loss of touch with reality)
Comer (2004)
•Over inclusion and ‘patholologizing’ problems
•The DSM keeps expanding
•According to Comer 48% of Americans might qualify for
a diagnosis on the DSM.
•E.g. mood changes with the menstrual cycle should that
really be seen as ‘Pre Menstrual Dysphoric Disorder’?
This could be seen as ‘pathologizing’ what is normal
behavior for women (gender bias).
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In the 1960s and 70s there was some concern among
psychiatrists that they gave diagnosis of schizophrenia too
readily.
There was an even greater concern that many people where
admitted to mental hospitals when they were not mentally ill,
and once admitted they were detained and given treatment
without their informed consent.
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Rosenhan’s key study supports this and led to the revision of
the DSM.
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Rosenhan's study raises questions about the content validity of
the DSM.
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Content validity being whether the DSM actually measures
what it sets out to measure.
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Validity is always going to be a problem for mental health workers –
because unlike physical illnesses – the symptoms are not clear cut
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E.g. a person suffering from schizophrenia may or may not exhibit
paranoia, they may or may not hear voices.
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Rosenhan’s research showed the low level of validity in the diagnosis of
mental illness
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However – the diagnosis was high in inter rater reliability – since nearly
all the ‘pseudo patients’ where given the diagnosis of schizophrenia –
but this was not a valid diagnosis.
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This shows that a diagnosis may be high in reliability and low in validity
at the same time.
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Each edition of the DSM attempts to improve both the reliability and
validity of diagnostic criteria.
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Look at page 142 in your textbook
Answer the questions about Rosenhan’s
study in the ‘Be a critical thinker’ box
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Andrews & Peters (1997) developed the CIDI to improve
the reliability and validity of the DSM.
This involves the client working through a structured
interview either using a computer program or with an
assistant.
They answer a range of questions on psychological
disorders and their responses are used to determine
which questions from the pool are asked or omitted.
If enough symptoms occur in patterns or clusters, then a
diagnosis is made. All this is done by a computer
program.
A more acceptable method
 Patients feel more comfortable answering
questions on a computer
 It gave them the opportunity to reveal symptoms
they had never been asked before
 Less subjective
High reliability and validity
 Research suggests that the CIDI is high in validity
and reliability
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There is a large amount of research supporting
the view that the reliability and validity of
diagnosis are poor. This is due to many reasons,
e.g. a possible social construction of mental
illness, poor diagnostic tools, the possibility of
faking, social influence, errors in attribution by
practitioners and labeling
There are significant individual and cultural
differences for the symptoms of mental
disorders.
An individual may have multiple mental disorders
A wrong diagnosis may lead to a social stigma
(an ethical issue)
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There are methodological problems with the studies on
validity and reliability (researcher bias, generalisability,
ecological validity)
Revised diagnostic tools are higher in reliability than
earlier versions, e.g. DSM-IV-TR
Many people do seek help voluntarily for disorders
(which may mean that the disorder is valid)
The reliability of diagnosis is high for some disorders,
e.g. obsessive compulsive disorder
There are many similarities of disorders across cultures
Diagnostic systems do not classify people, but the
disorders that they have
Alternative methods for diagnosis are being developed
all the time
Have a go at defining the following terms
Validity
Reliability
ICD
DSM
Diagnosis
Classification
Validity:
this is the extent to which the diagnosis is accurate.
Reliability:
this is how effective the use of a particular method of diagnosis (for example the
DSM) is at identifying a disorder.
ICD:
(International Classification of Diseases and Related Health Problems): The classification
system for medical and mental health problems used by the World Health Organization (WHO).
DSM:
(The Diagnostic and Statistical Manual of Mental Disorders): The classification and
diagnosis system developed by the American Psychiatric Association (APA).
Diagnosis:
is the process of identifying a medical condition or disease by its signs (what the
physician sees), symptoms (what the patient says), and from the results of various diagnostic
procedures.The conclusion reached through this process is called a diagnosis. Diagnosis is a
clinical judgment on the part of the psychiatrist.
Classification:
A list of disorders along with descriptions of symptoms and guidelines for
making appropriate diagnosis (Comer, 2004). For example, deciding what schizophrenia is as
apposed to depression.