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Logo of bmjThe BMJ
BMJ. 2002 July 20; 325(7356): 149–152.
PMCID: PMC1123674
ABC of psychological medicine

Depression in medical patients

Depressive illness is usually treatable. It is common and results in marked disability, diminished survival, and increased healthcare costs. As a result, it is essential that all doctors have a basic understanding of its diagnosis and management. In patients with physical illness depression may

  • Be a coincidental association
  • Be a complication of physical illness
  • Cause or exacerbate somatic symptoms (such as fatigue, malaise, or pain).

Clinical features and classification

The term depression describes a spectrum of mood disturbance ranging from mild to severe and from transient to persistent. Depressive symptoms are continuously distributed in any population but are judged to be of clinical significance when they interfere with normal activities and persist for at least two weeks, in which case a diagnosis of a depressive illness or disorder may be made. The diagnosis depends on the presence of two cardinal symptoms of persistent and pervasive low mood and loss of interest or pleasure in usual activities.

Criteria for major depression*

Five or more of the following symptoms during the same two week period representing a change from normal

 Depressed mood† Decreased interest or  pleasure†
 Substantial weight loss or weight gain Psychomotor retardation or  agitation
 Insomnia or hypersomnia Fatigue or loss of energy
 Feelings of worthlessness or inappropriate guilt Diminished ability to think or  concentrate
 Recurrent thoughts of death or suicide or suicide attempt

*From Diagnostic and Statistical Manual of Mental Disorders, fourth edition†One of these symptoms must be present

Adjustment disorders are milder or more short lived episodes of depression and are thought to result from stressful experiences.

Major depressive disorder refers to a syndrome that requires the presence of five or more symptoms of depression in the same two week period.

Dysthymia covers persistent symptoms of depression that may not be severe enough to meet the criteria for major depression, in which depressed mood is present for two or more years. Such chronic forms of depression are associated with an increased risk of subsequent major depression, considerable social disability, and unhealthy lifestyle choices such as poor diet or cigarette smoking.

Manic depressive (bipolar) disorder relates to the occurrence of episodes of both major depression and mania.


The World Health Organization estimates that depression will become the second most important cause of disability worldwide (after ischaemic heart disease) by 2020. Major depressive disorder affects 1 in 20 people during their lifetime. Both major depression and dysthymia seem to be more common in women.

Depressive illness is strongly associated with physical disease. Up to a third of physically ill patients attending hospital have depressive symptoms. Depression is even more common in patients with

  • Life threatening or chronic physical illness
  • Unpleasant and demanding treatment
  • Low social support and other adverse social circumstances
  • Personal or family history of depression or other psychological vulnerability
  • Alcoholism and substance misuse
  • Drug treatments that cause depression as a side effect, such as antihypertensives, corticosteroids, and chemotherapy agents.

Risk factors

Anxiety, sadness, and somatic discomfort are part of the normal psychological response to life stress, including medical illness. Clinical depression is a final common pathway resulting from the interaction of biological, psychological, and social factors. The likelihood of this outcome depends on such factors as genetic and family predisposition, the clinical course of a concurrent medical illness, the nature of the treatment, functional disability, the effectiveness of individual coping strategies, and the availability of social and other support.

In the attempts to understand the relation between physical illness and depression there has been much debate about the direction of causality. In particular, there has been speculation that certain illnesses—such as stroke, Parkinson's disease, multiple sclerosis, and pancreatic cancer—may cause depression via direct biological mechanisms. Stroke has perhaps received the most attention, but studies have failed to convincingly show direct aetiological mechanisms.

Reasons why depression is missed

  • Difficulty distinguishing psychological symptoms of depression, such as sadness and loss of interest, from a “realistic” response to stressful physical illness
  • Confusion over whether physical symptoms of depression are due to an underlying medical condition
  • Negative attitudes to diagnosis of depression
  • Unsuitability of clinical setting for discussion of personal and emotional matters
  • Patients' unwillingness to report symptoms of depression

Recognition and diagnosis

In spite of its enormous clinical and public health importance, depressive illness is often underdiagnosed and undertreated, particularly when it coexists with physical illness. This often causes great distress for patients who have mistakenly assumed that symptoms such as weakness or fatigue are due to an underlying medical condition.

All medical practitioners must be able to diagnose and manage depressive illness effectively. This depends on

  • Alertness to clues in interviews
  • Patients' manner

• The use of screening questions in those at risk—in particular, two questions about low mood and lack of pleasure in life can detect up to 95% of patients with major depression.

Screening questions for depression

  • How have you been feeling recently?
  • Have you been low in spirits?
  • Have you been able to enjoy the things you usually enjoy?
  • Have you had your usual level of energy, or have you been feeling tired?
  • How has your sleep been?
  • Have you been able to concentrate on newspaper articles or your favourite television or radio programmes?

Self report screening instruments, such as the Beck depression inventory (BDI) and the hospital anxiety and depression scale (HADS) cannot replace systematic clinical assessment, but they are useful in drawing attention to depression and other emotional disturbances in clinical settings where mood is not routinely assessed. Doctors must be aware that persistent low mood and lack of interest and pleasure in life cannot be accounted for by severe physical illness alone. The usual response to illness and treatment is impressive resilience.

If there is doubt about the diagnosis, a doctor may resort to an empirical trial of treatment to establish whether there is benefit. The wider availability of safer drugs and psychological treatments makes this option more attractive than in the past.


The main aims of treatment are to improve mood and quality of life, reduce the risk of medical complications, improve compliance with and outcome of physical treatment, and facilitate the “appropriate” use of healthcare resources. The development of a treatment plan depends on systematic assessment that should, whenever possible, not only involve the patients but also their partners or other key family members.

Milder or briefer adjustment disorders can be managed by primary care staff without recourse to specialist referral. Education, advice, and reassurance are of value. It is important that primary care staff are familiar with the properties and use of the commoner antidepressant drugs, and the value of brief psychological treatments such as cognitive behaviour therapy, interpersonal therapy, and problem solving.

Patients with more enduring or severe symptoms will usually require specific forms of treatment, usually drug treatment. Staff should also be able to assess suicidal thinking and risk. For patients with suicidal ideation or those whose depression has not responded to initial management, specialist referral is the next step in management.

Clinical assessment of suicidal intent

Low level risk

Clinical pictureAction
 Suicidal ideation but no suicide attemptsConsider referral to mental health professional for routine appointment (not always necessary)
 Supportive environment
 Physically healthy
 No history of psychiatric illness

Moderate level risk

Clinical pictureAction
 Low lethality suicide attempt (patient's perception of lethality)Refer to mental health professional, to be seen as soon as possible
 Frequent thoughts of suicide
 Previous suicide attempts
 Persistent depressive symptoms
 Serious medical illness
 Inadequate social support
 History of psychiatric illness

High level risk

Clinical pictureAction
 Definite plan for suicide (When? Where? How?)Refer to mental health professional for immediate assessment
 Major depressive disorder, severe
 High lethality suicide attempt or multiple attempts
 Advanced medical disease
 Social isolation
 History of psychiatric illness

Drug treatment

Antidepressants have been shown to be effective in treating major depressive disorder irrespective of whether the mood disturbance is “understandable.” There have been far fewer trials of antidepressants in patients who are also physically unwell, but the available evidence is in keeping with the treatment of depression generally.

One of the commonest questions is which antidepressant should be used. For non-specialists, the range of available drugs, and the claims made about them can be bewildering. There are four main classes of antidepressant

  • Tricyclics
  • Selective serotonin reuptake inhibitors
  • Monoamine oxidase inhibitors
  • Others (noradrenaline reuptake inhibitors).

Data from the Cochrane Collaboration and other systematic reviews show that the differences in overall tolerability between different preparations is minimal. In general, patients are slightly less likely to drop out of trials because of unacceptable side effects when taking a selective serotonin reuptake inhibitor but are slightly less likely to drop out because of treatment inefficacy when taking a tricyclic. Rather than continuously experimenting with a range of different drugs, clinicians should stick to prescribing one drug from each class in order to become familiar with their dosing regimens, actions, interactions, and side effects. Clinicians should also be aware that in certain situations one class of drug may be more advisable than others.

The debate about different preparations has obscured a potentially more important issue—that of drug dose and compliance. Most prescriptions for antidepressants are for inadequate doses and for inadequate time periods. This problem is compounded by only a minority of patients complying with the prescribed treatment. A recent household survey by the Royal College of Psychiatrists showed that many people believed that antidepressants were addictive and could permanently damage the brain.

To treat patients successfully with antidepressants, doctors must be able to show their patient that they have understood the patient's problems, considered the issues, and are advising the best available treatment (see previous articles). Before starting treatment, patients should be given an explanation of side effects and be reassured that side effects tend to be worse during the first two weeks of treatment and then diminish. They need to be warned that they are unlikely to feel benefits from treatment in the first four weeks. They should be given follow up appointments during this period in order to encourage compliance.

After initial treatment has led to remission of symptoms, subsequent treatment can be divided into two phases. Firstly, four to six months of continuous treatment at full dose are necessary to consolidate remission and prevent early relapse. Secondly, consideration must be given to preventive maintenance treatment, to reduce the risks of recurrence of depression. This is usually indicated if the patient has had two or more episodes of depression within the past five years. Psychological treatment may also help to prevent recurrence and can be used in combination with drug treatment.

Problem solving in psychological treatment

  • Define and list the problems
  • Choose a problem for action
  • List alternative courses of action
  • Evaluate courses of action and choose the best
  • Try the action
  • Evaluate the results
  • Repeat until major problems have been solved

Psychological treatment

Psychological treatment can range from discussion and simple problem solving to more specialised cognitive or dynamic behavioural psychotherapies. In many cases, brief treatment by non-specialists in primary and secondary care can be effective. Such interventions may include education and reassurance about the common reactions to the threats and losses associated with illness and empathic listening to patients' views, uncertainties, and beliefs about the illness. Education and advice about the medical condition and associated depression may prevent needless worry, reduce feelings of helplessness, and diminish irrational fears. Therapeutic approaches that support or promote active coping strategies are an important aspect of treatment in physically ill patients.

Evidence based summary

  • Depressive illness is an important cause of morbidity and disability in physically ill patients
  • All patients with depression should be examined for suicidal ideation
  • Depression is treatable in physically ill patients

Wells KB, Stewart A, Hays RD, Burnam MA, Rogers W, Daniels M, et al. The functioning and well-being of depressed patients. Results from the medical outcomes study. JAMA 1989;262:914-9

Carson AJ, Best S, Warlow C, Sharpe M. How common is suicidal ideation among neurology outpatients? BMJ 2000;320:1311-2

Gill D, Hatcher S. Antidepressants for depression in medical illness. Cochrane Database Syst Rev 2000;(4):CD001312

Cognitive behavioural principles may be used by non-specialists to correct distorted thinking and to encourage behaviours that contribute to patients' sense of mastery and wellbeing. Training in briefer forms of treatment using cognitive behavioural principles for primary care staff may be a worthwhile investment.

Cognitive behaviour therapy, interpersonal therapy, and problem solving have all been shown to be effective for treating depression, although there has been only limited evaluation of their effectiveness in physically ill populations. Although time consuming by comparison with drug treatment, psychological treatment may reduce relapse rates and may be cost effective in the long run. Some patients may require preliminary treatment with drugs to enable them to make best use of psychological treatment.

Further reading

  • Kessler RC, McGonagle KA, Zhao S, Nelson CB, Hughes M, Eshleman S, et al. Lifetime and 12-month prevalence of DSM-IIIR psychiatric disorders in the United States: results of the national comorbidity survey. Arch Gen Psychiatr 1994;51,8-19
  • Rodin G, Craven J, Littlefield C. Depression in the medically ill: an integrated approach. New York NY: Brunner/Mazel, 1991
  • Royal College of Physicians, Royal College of Psychiatrists. The psychological care of medical patients: recognition of need and service provision. London: RCP, RCPsych, 1995

Service organisation

Depression is so common in physically ill patients that it is not feasible for all cases to be managed by mental health specialists. There are advantages to collaborative management with primary care staff working closely with mental health specialists. Community based mental health services may be less accessible to general hospitals and often lack specialist knowledge about assessment and treatment when an important physical illness is also present. Liaison psychiatry services are often well placed to provide support, training, and psychiatric expertise to general hospital patients in a timely fashion.

Aretaeus of Cappadocia (circa 81-138 ad) is credited with the first clinical description of depression
“Neurotic” symptoms, including depression, are continuously distributed in the UK population
The association between depression and mortality after myocardial infarction
Pathways to depression
Physical symptoms that may be due to depression
Meta-analysis of randomised controlled trials comparing tricyclic antidepressants with selective serotonin reuptake inhibitors
Chart of clinical course indicating remission, recovery, and relapse


The diagram of the distribution of neurotic symptoms in the UK population is adapted from Jenkins et al Psychol Med 1997;27:765-74. The graph of association between depression and mortality after myocardial infarction. is adapted from Frasure Smith et al JAMA 1993;270: 1819-25. The diagram showing pathways to depression is adapted from Rodin et al Depression in the medically ill 1991. The meta-analysis of trials comparing antidepressants is adapted from Gill and Hatcher Cochrane Database Syst Rev 2000;(4):CD001312.


Robert Peveler is professor of liaison psychiatry, University of Southampton. Alan Carson is consultant neuropsychiatrist, NHS Lothian, and honorary senior lecturer, University of Edinburgh. Gary Rodin is professor of psychiatry, University of Toronto, Canada.

The ABC of psychological medicine is edited by Richard Mayou, professor of psychiatry, University of Oxford; Michael Sharpe, reader in psychological medicine, University of Edinburgh; and Alan Carson. The series will be published as a book in winter 2002.

Articles from The BMJ are provided here courtesy of BMJ Publishing Group