Psychological medicine

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Chapter 23 Psychological medicine

Introduction

Psychiatry is concerned with the study and management of disorders of mental function: primarily thoughts, perceptions, emotions and purposeful behaviours. Psychological medicine, or liaison psychiatry, is the discipline within psychiatry that is concerned with psychiatric and psychological disorders in patients who have physical complaints or conditions. This chapter will primarily concern itself with this particular branch of psychiatry.

The long-held belief that diseases are either physical or psychological has been replaced by the accumulated evidence that the brain is functionally or anatomically abnormal in most if not all psychiatric disorders. Physical, psychological and social factors, and their interactions must be looked into, in order to understand psychiatric conditions. This philosophical change of approach rejects the Cartesian dualistic approach of the mind/body biomedical model and replaces it with the more integrated biopsychosocial model.

Epidemiology (Box 23.1)

The prevalence of psychiatric disorders in the community in the UK is about 20%, mainly composed of depressive and anxiety disorders and substance misuse (mainly alcohol). The prevalence is about twice as high in patients attending the general hospital, with the highest rates in the accident and emergency department and medical wards.

Box 23.1

The approximate prevalence of psychiatric disorders in different populations

	Approximate percentage
Community	20
Neuroses	16
Psychoses	0.5
Alcohol misuse	5
Drug misuse	2 (an underestimate)
(total in community 20% due to co-morbidity)
Primary care	25
General hospital outpatients	30
General hospital inpatients	40

Culture and ethnicity

These can alter either the presentation or the prevalence of psychiatric ill-health. Biological factors in mental illness are usually similar across cultural boundaries, whereas psychological and social factors will vary. For example, the prevalence and presentation of schizophrenia vary little between countries, suggesting that biological/genetic factors are operating independently of cultural factors. In contrast, disorders in which social factors play a greater role vary between cultures, so that anorexia nervosa is found more often in developed cultures. Culture can also influence the presentation of illnesses, such that physical symptoms are more common presentations of depressive illness in Asia than in Europe. Similarly culture will influence the healthcare sought for the same condition.

The psychiatric history

As in any medical specialty, the history is essential in making a diagnosis. It is similar to that used in all specialties but tailored to help to make a psychiatric diagnosis, determine possible aetiology, and estimate prognosis. Data may be taken from several sources, including interviewing the patient, a friend or relative (usually with the patient’s permission), or the patient’s general practitioner. The patient interview also enables a doctor to establish a therapeutic relationship with the patient. Box 23.2 gives essential guidance on how to safely conduct such an interview, although it is unlikely that a patient will physically harm a healthcare professional. When interviewing a patient for the first time, follow the guidance outlined in Chapter 1 (see pp. 10–12).

Box 23.2

The essentials of a safe psychiatric interview

Beforehand: Ask someone of experience who knows the patient whether it is safe to interview the patient alone.

Access to others: If in doubt, interview in the view or hearing of others, or accompanied by another member of staff.

Setting: If safe; in a quiet room alone for confidentiality, not by the bed.

Seating: Place yourself between the door and the patient.

Alarm: If available, find out where the alarm is and how to use it.

Components of the history are summarized in Table 23.1.

Table 23.1 Summary of the components of the psychiatric history

Component	Description
Reason for referral	Why and how the patient came to the attention of the doctor
Present illness	How the illness progressed from the earliest time at which a change was noted until the patient came to the attention of the doctor
Past psychiatric history	Prior episodes of illness, where were they treated and how? Prior self-harm
Past medical history	Include emotional reactions to illness and procedures
Family history	History of psychiatric illnesses and relationships within the family
Personal (biographical) history	Childhood: Pregnancy and birth (complications, nature of delivery), early development and attainment of developmental milestones (e.g. learning to crawl, walk, talk). School history: age started and finished; truancy, bullying, reprimands; qualifications
Personal (biographical) history	Adulthood: Employment (age of first, total number, reasons for leaving, problems at work), relationships (sexual orientation, age of first, total number, reasons for endings of relationships), children and dependants
Reproductive history	In women: include menstrual problems, pregnancies, terminations, miscarriages, contraception and the menopause
Social history	Current employment, benefits, housing, current stressors
Personality	This may help to determine prognosis. How do they normally cope with stress? Do they trust others and make friends easily? Irritable? Moody? A loner? This list is not exhaustive
Drug history	Prescribed and over-the-counter medication, units and type of alcohol/week, tobacco, caffeine and illicit drugs
Forensic history	Explain that you need to ask about this, since ill-health can sometimes lead to problems with the law. Note any violent or sexual offences. This is part of a risk assessment. Worst harm they have ever inflicted on someone else? Under what circumstances? Would they do the same again were the situation to recur?
Systematic review	Psychiatric illness is not exclusive of physical illness! The two may not only co-exist but may also have a common aetiology

The mental state examination (MSE)

The history will already have assessed several aspects of the MSE, but the interviewer will need to expand several areas as well as test specific areas, such as cognition. The MSE is typically followed by a physical examination and is concluded with an assessment of insight, risk and a formulation that takes into account a differential diagnosis and aetiology. Each domain of the MSE is given below; abnormalities that might be detected and the disorders in which they are found are summarized in Table 23.2. The major subheadings are listed below.

Table 23.2 The mental state examination and the psychopathology it is used to detect

Abnormal perceptions

The assessment of perceptions in the mental state involves observation of the patient as well as asking questions of them. For example, patients experiencing auditory hallucinations may appear startled by sounds or voices that you cannot hear or may interact with them, e.g. appearing to be engaged in conversation when nobody else is in the room.

Hallucinatory phenomena can affect any sensory modality and specific types of hallucination will be dealt with later in the chapter with the disorders in which they most commonly occur.

Cognitive state

Examination of the cognitive state is necessary to diagnose organic brain disorders, such as delirium and dementia. Poor concentration, confusion and memory problems are the most common subjective complaints. Clinical testing involves the screening of cognitive functions, which may suggest the need for more formal psychometry. A premorbid estimate of intelligence, necessary to judge changes in cognitive abilities, can be made from asking the patient the final year level of education and the highest qualifications or skills achieved.

Testing can be divided into tests of diffuse and focal brain functions.

Diffuse functions

Orientation in time, place and person. Consciousness can be defined as the awareness of the self and the environment. Clouding of consciousness is more accurately a fluctuating level of awareness and is commonly seen in delirium.

Attention is tested by saying the months or days backwards.

Verbal memory. Ask the patient to repeat a name and address with 10 or so items, noting how many times it takes to recall it 100% accurately (normal is 1 or 2) (immediate recall or registration).

– Ask the patient to try to remember it and then ask it of them again after 5 min (0 or 1 error is normal) (short-term memory).

Long-term memory. Ask the patient to recall the news of that morning or recently. If they are not interested in the news, find out their interests and ask relevant questions (about their football team or favourite soap opera). Amnesia is literally an absence of memory and dysmnesia indicates a dysfunctioning memory.

Focal functions

Frontal, temporal and parietal function tests are covered in chapter 22. Note any disinhibited behaviour not explained by another psychiatric illness. Sequential tasks are tested by asking the patient to alternate making a fist with one hand at the same time as a flat hand with the other. Ask the patient to tap a table once if you tap twice and vice-versa. Note any motor perseveration whereby the patient cannot change the movement once established. Observe for verbal perseveration, in which the patient repeats the same answer as given previously for a different question. Abstract thinking is measured by asking the meaning of common proverbs, a literal meaning suggesting frontal lobe dysfunction, assuming reasonable premorbid intelligence.

Assessing cognitive dysfunction

Questions on: orientation (e.g. time, date, place); registration (naming objects); attention and calculation (simple arithmetic); recall (previously mentioned objects); and language (understanding commands). This correlates well with more time-consuming intelligence quotient (IQ) tests, but it will not as easily pick up cognitive problems caused by focal brain lesions. Simple questioning will detect about 90% of people with cognitive impairments, with about 10% false positives.

Insight and illness beliefs

Insight is the degree to which a person recognizes that he or she is unwell, and is minimal in people with a psychosis. Illness beliefs are the patient’s own explanations of their ill health, including diagnosis and causes. These beliefs should be elicited because they can help to determine prognosis and adherence with treatment, whatever the diagnosis.

Risk

The assessment of risk may sound daunting but it is fundamental to clinical practice; for instance when determining whether a patient presenting with chest pain should be reviewed in the resuscitation room of the emergency department rather than a normal cubicle. Risk must be assessed in people with a psychiatric diagnosis, albeit that the nature of ‘risk’ is different.

Risk can be broken down into two parts: the risk that the patient poses to themselves and that which they pose to others (Table 23.3). You will have already made an appraisal of risk in your initial preparations for seeing the patient (Box 23.2) and in checking ‘forensic history’ (Table 23.1). It may be necessary to obtain additional information from family, friends or professionals who know the patient – this may save time and prove invaluable.

Table 23.3 The assessment of risk

	Risk to self	Risk to others
Active	Acts of self-harm or suicide attempts	Aggression towards others – this may be actual violence or threatening behaviour
Active	Look for prior history of self-harm and what may have precipitated or prevented it	A past history of aggression is a good predictor of its recurrence. Look at the severity and quality of and remorse for prior violent acts as well as identifiable precipitants that might be avoided in the future (e.g. alcohol)
Passive	Self-neglect	Neglect of others – always find out whether children or other dependants are at home
Passive	Manipulation by others

Severe behavioural disturbance

Patients who are aggressive or violent cause understandable apprehension in all staff, and are most commonly seen in the accident and emergency department. Information from anyone accompanying the patient, including police or carers, can help considerably. Box 23.3 gives the main causes of disturbed behaviour.

Box 23.3

Main causes of disturbed behaviour

Drug intoxication (especially alcohol)

Delirium (acute confusional state)

Acute psychosis

Personality disorder

FURTHER READING

Folstein MF, Folstein SE, McHough PR. ‘Mini-mental state’: a practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res 1975; 12:189–198.

Management of the severely disturbed patient

The primary aims of management are control of dangerous behaviour and establishment of a provisional diagnosis. Three specific strategies may be necessary when dealing with the violent patient:

Reassurance and explanation

Medication.

Physical restraint.

Remember that the behaviour exhibited is a reflection of an underlying disorder and as such portrays suffering and often fear. The approach to the agitated or even the violent patient therefore must take this into account and the steps used are with the intention of alleviating this suffering whilst maintaining the safety of the individual, the other patients and staff. Technically speaking, this management begins at the point of an initial assessment that takes into account prior episodes of disturbed behaviour and its precipitants. Armed with this knowledge it may be possible to prevent a recurrence.

‘Verbal de-escalation’. If a patient’s behaviour causes concern, the first step is to try and defuse the situation. Put more simply, this means talking to the patient. It may be something that is relatively simple to correct that has led to the disturbed behaviour such as staff explaining their intentions in approaching the patient.

Medication may be used but an effort should always be made to offer this on an oral basis. The protocol in the UK is to offer a short-acting benzodiazepine in the first instance, such as lorazepam (0.5–1 mg). Patients suffering from a psychotic disorder and who are already taking antipsychotics may be more appropriately treated with an antipsychotic but do not assume that this is the case and be wary of the ‘neuroleptic-naive’ patient. In the delirious or elderly patient, benzodiazepines should be avoided, as they may worsen any underlying confusion and can cause paradoxical agitation. In this instance, low-dose haloperidol is appropriate (2.5–5 mg). More recently, antihistamines have been added to this protocol, such as promethazine. Medications should be given sequentially, rather than all at once, where possible and allowing between 30 min and 1 h for them to take effect.

Physical restraint. In the instance that the above measures do not resolve the situation, physical restraint may be necessary in order to maintain safety and to administer medications on an intramuscular basis (note that for haloperidol this will alter the maximum dose it is safe to use in a 24-hour period). This should not be the first step taken nor should it be performed by staff unless they have been adequately trained in approved methods of control and restraint. This will typically mean nursing staff on a psychiatric ward or security staff on a general medical or surgical ward. Although this may vary between countries, in the UK it is the case that doctors will never be involved in the restraint of the patient. Restraint is a potentially dangerous intervention, even more so when mixed with psychotropic medication, and deaths have occurred as a direct consequence.

Monitoring. If medications (oral or otherwise) are employed, with or without restraint, regular monitoring of physical parameters such as blood pressure, pulse, respiratory rate and oxygen saturation should be performed at a frequency dictated by the level of ongoing agitation and consciousness.

FURTHER READING

NICE. Violence: The short term management of disturbed/violent behaviour in in-patient psychiatric settings and emergency departments. Clinical Guideline 25. London: National Institute for Health and Clinical Excellence, February 2005; www.nice.org.uk

Defence mechanisms

Although not strictly part of the mental state examination, it is useful to be able to identify psychological defences in ourselves and our patients. Defence mechanisms are mental processes that are usually unconscious. Some of the most commonly used defence mechanisms are described in Table 23.4 and are useful in understanding many aspects of behaviour.

Table 23.4 Common defence mechanisms

Defence mechanism	Description
Repression	Exclusion from awareness of memories, emotions and/or impulses that would cause anxiety or distress if allowed to enter consciousness
Denial	Similar to repression and occurs when patients behave as though unaware of something that they might be expected to know, e.g. a patient who, despite being told that a close relative has died, continues to behave as though the relative were still alive
Displacement	Transferring of emotion from a situation or object with which it is properly associated to another that gives less distress
Identification	Unconscious process of taking on some of the characteristics or behaviours of another person, often to reduce the pain of separation or loss
Projection	Attribution to another person of thoughts or feelings that are in fact one’s own
Regression	Adoption of primitive patterns of behaviour appropriate to an earlier stage of development. It can be seen in ill people who become child-like and highly dependent
Sublimation	Unconscious diversion of unacceptable behaviours into acceptable ones

The relevant physical examination

This should be guided by the history and mental state examination. Particular attention should usually be paid to the neurological and endocrinological examinations when organic brain syndromes and affective illnesses are suspected.

Summary or formulation

When the full history and mental state have been assessed, the doctor should make a concise assessment of the case, which is termed a formulation. In addition to summarizing the essential features of the history and examination, the formulation includes a differential diagnosis, a discussion of possible causal factors, and an outline of further investigations or interviews needed. It concludes with a concise plan of treatment and a statement of the likely prognosis.

Classification of psychiatric disorders

The classification of psychiatric disorders into categories is mainly based on symptoms and behaviours, since there are currently few diagnostic tests for psychiatric disorders. There currently exists an unhelpful dualistic division of psychiatric disorders from neurological diseases, since the pathologies of at least the majority of each group of conditions are located in the brain, e.g. Alzheimer’s disease causing dementia and a pseudobulbar palsy causing emotional lability.

Psychiatric classifications have traditionally divided up disorders into neuroses and psychoses.

Neuroses are illnesses in which symptoms vary only in severity from normal experiences, such as depressive illness.

Psychoses are illnesses in which symptoms are qualitatively different from normal experience, with little insight into their nature, such as schizophrenia.

There are several problems with a neurotic-psychotic dichotomy. First, neuroses may be as severe in their effects as psychoses. Second, neuroses may cause symptoms that fulfil the definition of psychotic symptoms. For instance, someone with anorexia nervosa may be convinced that they are fat when they are thin, and this belief would meet all the criteria for a delusional belief. Yet we would traditionally classify the illness as a neurosis.

The ICD-10 Classification of Mental and Behavioural Disorders published by the World Health Organization has largely abandoned the traditional division between neurosis and psychosis, although the terms are still used. The disorders are now arranged in groups according to major common themes (e.g. mood disorders and delusional disorders). A classification of psychiatric disorders derived from ICD-10 is shown in Table 23.5, and this is the classification mainly used in this chapter (ICD-11 will be available in 2014).

Table 23.5 International classification of psychiatric disorders (ICD-10)

Organic disorders

Mental and behavioural disorders due to psychoactive substance use

Schizophrenia and delusional disorders

Mood (affective) disorders

Neurotic, stress-related and somatoform disorders

Behavioural syndromes

Disorders of adult personality and behaviour

Mental retardation

The Diagnostic and Statistical Manual of the American Psychiatric Association (DSM-IV-TR) is an alternative classification system (DSM-V in 2013).

FURTHER READING

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 5th edn. Text Revision (DSM-5). Washington, DC: APA; 2013.

World Health Organization. The ICD-10 Classification of Mental and Behavioural Disorders: Clinical Descriptions and Diagnostic Guidelines. Geneva: World Health Organization; 1992.

Causes of a psychiatric disorder

A psychiatric disorder may result from several causes which may interact. It is most helpful to divide causes into the three ‘Ps’: predisposing, precipitating and perpetuating factors.

Predisposing factors often stem from early life and include genetic, pregnancy and delivery, previous emotional traumas and personality factors.

Precipitating (triggering) factors may be physical, psychological or social in nature. Whether they produce a disorder depends on their nature, severity and the presence of predisposing factors. For instance a death of a close, rather than distant, family member is more likely to precipitate a pathological grief reaction in someone who has not come to terms with a previous bereavement.

Perpetuating (maintaining) factors prolong the course of a disorder after it has occurred. Again they may be physical, psychological or social, and several are often active and interacting at the same time. For example, high levels of criticism at home combined with taking cannabis, as relief from the criticism, may help to maintain schizophrenia.

Psychiatric aspects of physical disease

People with non-psychiatric, ‘physical’ diseases are more likely to suffer from psychiatric disorders than those who are well. The most common psychiatric disorders in physically unwell patients are mood or adjustment disorders and acute organic brain disorders (delirium). The relationship between psychological and physical symptoms may be understood in one of four ways:

Psychological distress and disorders can precipitate physical diseases (e.g. the cardiac risk associated with depressive disorders or hypokalaemia causing arrhythmias in anorexia nervosa).

Physical diseases and their treatments can cause psychological symptoms or ill-health (Table 23.6).

Both the psychological and physical symptoms are caused by a common disease process (e.g. Huntington’s chorea).

Physical and psychological symptoms and disorders may be independently co-morbid, particularly in the elderly.

Table 23.6 Psychiatric conditions sometimes caused by physical diseases

Psychiatric disorders/symptom	Physical disease
Depressive illness	Hypothyroidism
	Cushing’s syndrome
	Steroid treatment
	Brain tumour
Anxiety disorder	Thyrotoxicosis
	Hypoglycaemia (transient)
	Phaeochromocytoma
	Complex partial seizures (transient)
	Alcohol withdrawal
Irritability	Post-concussion syndrome
	Frontal lobe syndrome
	Hypoglycaemia (transient)
Memory problem	Brain tumour
Memory problem	Hypothyroidism
Altered behaviour	Acute drug intoxication
	Postictal state
	Acute delirium
	Dementia
	Brain tumour

Factors that increase the risk of a psychiatric disorder in someone with a physical disease are shown in Table 23.7.

Table 23.7 Factors increasing the risk of psychiatric disorders in the general hospital

Patient factors

Previous psychiatric history

Current social or interpersonal stresses

Homelessness

Recent alcohol misuse

Setting

A&E department

Neurology, oncology and endocrinology wards

Intensive care unit

Renal dialysis unit

Physical conditions

Chronic ill-health

Chronic pain

Life-threatening illness

Recent bad prognostic news

Disabling condition

Brain disease

Recent live birth, stillbirth or miscarriage

Functional illness

Treatment

Certain drugs (e.g. dopamine agonists)

Second postoperative day

Surgery affecting body image (e.g. emergency stomata)

FURTHER READING

Moussavi S, Chatterii S, Verdes E et al. Depression, chronic diseases, and decrements in health: results from the World Health Surveys. Lancet 2007; 370:851–858.

Differences in treatment

Although the basic principles are the same as in treating psychiatric illnesses in the physically healthy, there are some differences:

Uncertainty regarding the physical diagnosis or prognosis, with its attendant tendency to imagine the worst, is often a triggering or maintaining factor, particularly in an adjustment or mood disorder. Good two-way communication between doctor and patient, with time taken to listen to the patient’s concerns, is often the most effective ‘antidepressant’ available.

The history may reveal the role of a physical disease or treatment exacerbating the psychiatric condition, which should then be addressed (Table 23.6). For example, the dopamine agonist bromocriptine can precipitate a psychosis.

When prescribing psychotropic drugs, the dose should be reduced in disorders affecting pharmacokinetics, e.g. fluoxetine in renal or hepatic failure.

Drug interactions should be of particular concern, e.g. lithium and non-steroidal anti-inflammatory drugs.

Sometimes a physical treatment may be planned that may exacerbate the psychiatric condition. An example would be high-dose steroids as part of chemotherapy in a patient with leukaemia and depressive illness.

Always remember the risk of suicide in an inpatient with a mood disorder and take steps to reduce that risk; for example, moving the patient to a room on the ground floor and/or having a registered mental health nurse attend the patient while at risk.

The sick role and illness behaviour

The sick role describes behaviour usually adopted by ill people. Such people are not expected to fulfil their normal social obligations. They are treated with sympathy by others and are only obliged to see their doctor and take medical advice or treatments.

Illness behaviour is the way in which given symptoms may be differentially perceived, evaluated and acted (or not acted) upon by different kinds of persons. We all have illness behaviour when we choose what to do about a symptom. Going to see a doctor is generally more likely with more severe, distressing and numerous symptoms. It is also more likely in introspective individuals who focus on their health.

Abnormal illness behaviour occurs when there is a discrepancy between the objective pathology present and the patient’s response to it, in spite of adequate medical investigation and explanation.

Functional or psychosomatic disorders

So-called functional (in contrast to ‘organic’) disorders are illnesses in which there is no obvious pathology or anatomical change in an organ and there is a presumed dysfunction of an organ or system. Examples are given in Table 23.8. The psychiatric classification of these disorders would be somatoform disorders, but they do not fit easily within either medical or psychiatric classification systems, since they occupy the borderland between them. This classification also implies a dualistic ‘mind or body’ dichotomy, which is not supported by neuroscience. Since current classifications still support this outmoded understanding, this chapter will address these conditions in this way.

Table 23.8 ‘Functional’ somatic syndromes

The word psychosomatic has had several meanings, including psychogenic, ‘all in the mind’, imaginary and malingering. The modern meaning is that psychosomatic disorders are syndromes in which both physical and psychological factors are likely to be causative. So-called medically unexplained symptoms and syndromes are very common in both primary care and the general hospital (over half the outpatients in gastroenterology and neurology clinics have these syndromes). Because orthodox medicine has not been particularly effective in treating or understanding these disorders, many patients perceive their doctors as unsympathetic and seek out complementary or even alternative treatments of uncertain efficacy.

Because epidemiological studies suggest that having one of these syndromes significantly increases the risk of having another, some doctors believe that these syndromes represent different manifestations of a single ‘functional syndrome’, indicating a global somatization process. Functional disorders also have a significant association with depressive and anxiety disorders. Against this view is the evidence that the majority of primary care people with most of these disorders do not have either a mood or other functional disorder. It also seems that it requires a major stress or the development of a co-morbid psychiatric disorder in order for such sufferers to see their doctor, which might explain why doctors are so impressed with the associations with both stress and psychiatric disorders. Doctors have historically tended to diagnose ‘stress’ or ‘psychosomatic disorders’ in people with symptoms that they cannot explain. History is full of such disorders being reclassified as research clarifies the pathology. An example is writer’s cramp (p. 1122) which most neurologists now agree is a dystonia rather than a neurosis.

The likelihood is that these functional disorders will be reclassified as their causes and pathophysiology are revealed. Functional brain scans suggest enhancement of brain activity during interoception in more than one syndrome. Interoception is the perception of internal (visceral) phenomena, such as a rapid heartbeat.

Chronic fatigue syndrome (CFS)

There has probably been more controversy over the existence and cause of CFS than any other ‘functional’ syndrome in recent decades. This is reflected in its uncertain classification as neurasthenia in the psychiatric classification and myalgic encephalomyelitis (ME) under neurological diseases. There is now good evidence for the independent existence of this syndrome, although the diagnosis is made clinically and by exclusion of other fatiguing disorders. Its prevalence is 0.5–2.5% worldwide, mainly depending on how it is defined. It occurs most commonly in women between the ages of 20 and 50 years.

Clinical features

The cardinal symptom is chronic fatigue made worse by minimal exertion. The fatigue is usually both physical and mental, associated most commonly with:

poor concentration

impaired registration of memory

alteration in sleep pattern (either insomnia or hypersomnia)

muscular pain.

Mood disorders are present in a large minority of patients, and can cause problems in diagnosis because of the overlap in symptoms. These mood disorders may be secondary, independent (co-morbid), or primary (with a misdiagnosis of CFS).

Aetiology

Functional disorders often have some aetiological factors in common with each other (Table 23.9), as well as more specific aetiologies. For instance, CFS can be triggered by certain infections, such as infectious mononucleosis and viral hepatitis. About 10% of patients who have infectious mononucleosis have CFS 6 months after the onset of infection, yet there is no evidence of persistent infection in these patients. Those fatigue states which clearly do follow on a viral infection can also be classified as post-viral fatigue syndromes.

Table 23.9 Aetiological factors commonly seen in ‘functional’ disorders

Predisposing

Perfectionist, obsessional and introspective personality traits

Childhood traumas (physical and sexual abuse)

Precipitating (triggering)

Infections (chronic fatigue syndrome (CFS) and irritable bowel syndrome)

Traumatic events (especially accidents)

Physical problems (‘fibromyalgia’ and other chronic pain syndromes)

Life events that precipitate changed behaviours (e.g. going off sick)

Incidents where the patient believes others are responsible

Perpetuating (maintaining)