CLINICAL CHARACTERISTICS AND DIAGNOSIS OF DEPRESSION
To read up on the clinical characteristics and the diagnosis of depression, refer to
pages 425–431 of Eysenck’s A2 Level Psychology.
Ask yourself
 How is clinical depression different from feeling “down”?
 What are the symptoms of depression?
 Why do you think twice as many women as men are diagnosed with
depression?
What you need to know
CLINICAL CHARACTERISTICS OF
DEPRESSION

The physical and psychological
symptoms of depression including
physical/behavioural, perceptual,
cognitive, motivational, social, and
emotional
ISSUES SURROUNDING THE
CLASSIFICATION AND DIAGNOSIS OF
DEPRESSION


In particular you must consider
the issues of reliability and
validity
Further issues you may consider
are: culture bias; social issues
such as public and political
attitudes to abnormality; and the
economic implications of
diagnosis
CLINICAL CHARACTERISTICS OF DEPRESSION
Mood disorders are characterised by disturbances of affect (mood), which can be in
the direction of depression or elation. Mood disorders are distinguished from
normal mood variations by the duration and degree of disturbance. Depression is an
emotional response that can have physical, behavioural, perceptual, cognitive,
motivational, social, and emotional symptoms.
Major depression
Physical/behavioural symptoms:
 Appetite is usually reduced, but can increase (comfort eating) and tends to be
unhealthy.
 Sleep disturbances occur. Insomnia tends to be most common with problems
in falling asleep and early morning waking. Hypersomnia can also occur,
which is excessive sleeping, and may be an attempt to escape reality. Sleep
disturbances result in tiredness and feelings of lethargy (loss of energy) or
restlessness.
 Sex drive is usually reduced.
Perceptual symptoms:

Auditory hallucinations may occur, which are extreme forms of self-critical
delusions as the hallucinations often involve voices that are abusive and
critical of the depressive.
Cognitive symptoms:
Depressives have slow, muddled thinking and difficulty in making decisions.
Thinking is pessimistic, negative, and in severe cases suicidal. A negative selfconcept can lead to faulty thinking, when the individual is overly critical of him- or
herself—this can develop into delusions.
Motivational symptoms:
Depressives show a lack of interest (apathy) in their appearance, work, home, and
others. There is also reduced activity due to their lack of interest and energy.
Social symptoms:
Depressives usually show social withdrawal because they do not gain pleasure from
social interaction and may feel they have nothing to contribute and do not want
people to see them in their depressed state.
Emotional/mood symptoms:
 Depressives show low mood, unhappiness, anguish, and are often on the
verge of tears.
 They may experience anhedonia, which refers to a loss of pleasure in
activities previously enjoyed.
 Diurnal mood variations may occur in which the mood changes throughout
the day, being particularly low in the morning and improving a little as the
day progresses.
Classification of Depression
DSM-IV (Diagnostic and Statistical Manual, 4th edition; see A2 Level Psychology page
426), which is the American classification system, and ICD-10 (International
Classification of Diseases), the tenth edition of which was published by the World
Health Organization in 1992 (ICD-10; see A2 Level Psychology page 426), are the two
most common classification systems.
According to DSM-IV, diagnosis of major depression requires an episode of major
depression, which means five or more of the physical, perceptual, behavioural,
cognitive, social, and emotional symptoms must persist over a minimum period of 2
weeks, with one of the symptoms being depressed mood or loss of pleasure. An
individual with 2–4 depressive symptoms may be diagnosed with minor depression
but this is less likely to be formally diagnosed.
The criteria used in ICD-10 to diagnose a depressive episode are similar to those
used in DSM-IV. Severe depressive episodes must include the following symptoms
over at least a 2-week period: depressed mood most of the day and nearly every
day, loss of interest or pleasure in activities that are generally regarded as
pleasurable, and increased fatigue or reduced energy. Other symptoms must also be
present.
Types of Depression
Depression is the main symptom of a range of mood disorders, which include:
 Major depression (unipolar)
 Manic depression (bipolar disorder)
 Seasonal affective disorder (SAD)
 Premenstrual syndrome (PMS)
 Postpartum depression (PPD)
Major depression can be divided into different types:
 Endogenous—caused by factors within the person.
 Reactive—caused by factors external to the person, such as stressful life
events; this is the type that people are most likely to experience.
Although a useful distinction, this can be difficult to apply as the depression may be
due to internal and external factors. In clinical practice a distinction is often made
between minor, neurotic illness, and major, psychotic illness. The former is used
when there is mood disturbance only and the latter is used when there are also
severe cognitive and perceptual distortions, such as delusions and hallucinations.
ISSUES SURROUNDING THE CLASSIFICATION AND DIAGNOSIS OF DEPRESSION
For any diagnostic system to work effectively, it must possess reliability and
validity. Reliability means that there is good consistency over time and between
different people’s diagnosis of the same patient; known as inter-judge (or interrater) reliability. If diagnosis of depression is valid then patients who are diagnosed
as suffering from depression must have the disorder. If a diagnostic system is to be
valid, it must also have high reliability. Clearly if a disorder cannot be agreed upon
(so low reliability) then all of the different views cannot be correct (so low validity).
Whereas a diagnostic system can be reliable but not valid—it can produce
consistently wrong diagnoses.
In terms of classification, DSM-IV and ICD-10 take a categorical approach, which
assumes that all mental disorders are distinct from each other, and that patients can
be categorised with a disorder based on their having particular symptoms.
However, diagnosing abnormality is not as straightforward as this approach
suggests.
The categorical system
Several factors can reduce the reliability and validity of diagnosis of major
depressive disorder (unipolar depression).
 First, classification systems such as DSM-IV-TR (revised version of DSM-IV in
2000) and ICD-10 are categorical systems. This is an all-or-none approach in
which patients are assumed to have the disorder or not. This seems
straightforward but using the system in practice is not because a patient who

has six symptoms every day for 13 days would not meet the criteria, yet
clearly has experienced some depression.
Further evidence that the all-or-none system lacks validity is that those who
don’t meet the diagnosis of major depressive disorder or minor depressive
disorder do still have some form of depression, which may progress to major
depression. For example, Horwath et al. (1992, see A2 Level Psychology page
429) found that over 50% of new cases of major depressive disorder
(unipolar depression) had previously reported less severe symptoms of
depression.
Subjectivity of diagnosis
Judging whether patients have any given symptom is subjective because they cannot
be measured. For example, loss of pleasure in usual activities is a symptom of major
depressive disorder, but how much loss of pleasure is needed to qualify?
Comorbidity
Comorbidity means that a given individual has two or more mental disorders at the
same time. For example, many people suffer from both depression and anxiety. This
means the diagnostic categories in DSM-IV and ICD-10 are not distinct from each
other, yet the classification systems assume that they are.
EVALUATION
 Different forms of comorbidity mean it is difficult to make comparisons
between patients. It is also difficult for the therapist to know which disorder
to focus on first in treatment.
Diagnosis: Semi-structured interviews
Patients are generally diagnosed on the basis of one or more interviews with a
therapist. Some interviews are very unstructured and informal. This can produce
good rapport between the patient and the therapist, but reliability and validity of
diagnosis tend to be low (Hopko et al., 2004, see A2 Level Psychology page 430). The
most reliable and valid approach involves the use of semi-structured interviews in
which patients are asked a largely predetermined series of questions.
EVALUATION
 Semi-structured interviews do have good reliability and validity. Two of
the most used semi-structured interviews for depression are the Structured
Clinical Interview for DSM-IV-Patient Version (SCID-I/P) and the Anxiety
Disorder Interview Schedule for DSM-IV (ADIS-IV). Both interviews involve
systematic questioning about a range of symptoms common to depression.
 High reliability and accuracy. Inter-judge reliability and diagnostic
accuracy were both high with the SCID-I/P (Ventura et al., 1998, see A2 Level
Psychology page 430).
 Good reliability when used to assess depression but less so for other
anxiety disorders. ADIS-IV is mainly designed to diagnose anxiety
disorders. But it also provides an assessment of depression because many

patients suffer with both. Brown et al. (2001, see A2 Level Psychology page
430) found good inter-judge reliability when two therapists used ADIS-IV to
assess depression (i.e. the two therapists showed good agreement). However,
reliability was somewhat lower than for most of the anxiety disorders.
Different diagnoses and the “threshold issue”. This lack of reliability was
mainly due to patients reporting different symptoms during the two
interviews. However, there were also different diagnoses where one
therapist diagnosed depression and the other anxiety. The “threshold issue”
also reduces reliability because therapists sometimes disagreed as to
whether the symptoms exceeded the threshold; we considered this earlier in
terms of how much loss of pleasure the patient must show.
Content validity
Content validity refers to the extent to which an assessment procedure obtains
detailed relevant information. Thus, the diagnostic interviews have content validity
if they provide detailed information regarding all of the symptoms of depression.
EVALUATION
 Semi-structured interviews can have high content validity. SCID-I/P and
ADIS-IV are clearly both high in content validity.
Criterion validity
Any form of assessment for depression possesses good criterion validity if those
diagnosed as having depression differ in predictable ways from those not diagnosed
with depression.
EVALUATION
 Evidence for differences. There is evidence that patients diagnosed with
major depressive disorder are less likely to be in a long-lasting relationship,
to have a full-time job, or to have many friends (Hammen, 1997, see A2 Level
Psychology page 431).
 Difficult to distinguish depression from other mental disorders. This
provides some evidence for criterion validity, but note that poor social and
work functioning are found in those suffering from most mental disorders
and so this doesn’t distinguish patients with depression from patients with
other mental disorders.
Construct validity
Third, there is construct validity, which is the extent to which hypotheses about a
given disorder are supported by the evidence.
EVALUATION
 Evidence for depression being associated with a lack of involvement in
pleasurable activities. It is often assumed that depression is associated
with a lack of involvement in pleasurable activities, and the evidence

supports that assumption (Lewinsohn et al., 1992, see A2 Level Psychology
page 431).
Low levels of serotonin. Similarly, one hypothesis is that low levels of
serotonin are linked to depression and so the fact individuals with
depression have low levels of serotonin provides some evidence for
construct validity.
Gender bias
Females are twice as likely as men to be diagnosed with depression. Some suggest
this is due to gender bias—that females are being stereotyped as neurotic, and so
more likely to be diagnosed than male patients who present with the same
symptoms. However, there are a number of arguments against this—see the section
on socio-cultural explanations in Psychological Explanations of Depression for these
arguments (see A2 Level Psychology pages 448–449).
So what does this mean?
Overall, then, it seems that the main ways of diagnosing major depressive disorder
possess reasonable content, criterion, and construct validity. The many forms of
depression inevitably raise some issues of reliability and validity in diagnosis. The
two main systems of diagnosis, DSM-IV and ICD-10, have reasonably good content
validity as the research findings suggest they have sufficient detail of symptoms for
accurate diagnosis. However, there are many issues that question the reliability and
validity of diagnosis, such as the categorical approach, the subjectivity of diagnosis,
and comorbidity. Unstructured clinical interviews can lack reliability and validity.
However, the semi-structured interviews, SCID-I/P, and ADIS-IV have been found to
have reliability as two therapists’ diagnoses have been found to be high in
consistency, and they have high diagnostic accuracy (validity).
Over to you
1. Outline the clinical characteristics of depression. (5 marks)
2. Discuss the issues associated with the classification and diagnosis of depression.
(20 marks)