Somatoform and conversion/dissociative disorders: epidemiology, etiology, clinical features, course, and treatment. Consultation-Liaison Psychiatry

01Definition and overview

Somatoform and dissociative disorders share one idea: symptoms that look like those of a physical or neurological disease, or a loss of normal mental integration, that are real, not produced on purpose, and not explained by disease. The old terms (hysteria, psychogenic, medically unexplained) are giving way to functional disorders and persistent physical symptoms: a problem of how the nervous system works, not of its structure. Disease and a functional disorder often coexist.

The classifications have changed more here than anywhere else in psychiatry:

ICD-11 and DSM-5 no longer require the symptoms to be medically unexplained: bodily distress and somatic symptom disorder are defined by excessive distress and attention, which can accompany a known disease. Nor is a psychological cause required for functional neurological disorder, though stress often comes first.

What separates these disorders from feigned illness is intention and motive:

02Etiology and pathophysiology

Persistent bodily symptoms arise from many factors acting together, best thought of in three groups:

The brain does not simply register signals from the body: it predicts them. When attention is fixed on the body and expectations of illness are strong, these predictions can generate sensations or override normal movement, although the pathways are intact. In functional neurological disorder, imaging shows altered activity in networks for attention, emotion and the sense of agency, and these patterns differ from those of healthy people asked to feign the same weakness. In functional pain and fatigue syndromes, central sensitisation may amplify normal signals.

1. 1

   A symptom

   A normal sensation, a minor illness or an injury produces a symptom.
2. 2

   Threat

   It is read as a sign of serious disease, and attention fixes on the body, which makes the symptom stronger.
3. 3

   Help-seeking

   Tests and reassurance bring relief, but only briefly, and each new opinion raises another possibility.
4. 4

   Avoidance

   Rest, checking and avoiding activity lead to deconditioning, more symptoms and more disability.

Dissociation is a disruption of the normal integration of memory, identity, perception, movement and awareness. Brief dissociation is a normal response to overwhelming threat. Dissociative disorders are linked with trauma, especially in childhood, though not all patients have a trauma history. Dissociative identity disorder is contested: one view sees it as a response to severe early trauma, another as shaped partly by suggestion, culture and therapy. The psychodynamic idea of conflict converted into symptoms is no longer part of the definitions.

03Clinical features

Persistent bodily symptoms

In bodily distress disorder (ICD-11) and somatic symptom disorder (DSM-5), distressing bodily symptoms, often several and changing over time, sometimes a single one such as pain or fatigue, come with excessive attention to them: persistent worry about their seriousness, a great deal of time and energy spent on them, and repeated medical contact that examination, tests and reassurance do not settle. DSM-5 looks for at least six months.

ICD-10 somatisation disorder is the severe, chronic end: at least two years of multiple, changing symptoms, refusal to accept reassurance, and a life that revolves around illness, beginning in early adulthood, with thick case notes and often several operations. More often the symptoms fall in one specialty's field, as functional somatic syndromes:

These syndromes overlap. Chronic fatigue syndrome (ME/CFS) is placed here by some but seen by many as a physical illness, and NICE (2021) advises against graded exercise therapy for it. Health anxiety, a fear of having a serious disease, is covered with OCD's related disorders.

Functional neurological disorder

Its forms include weakness or paralysis, tremor, jerks and dystonia, gait disorders, sensory loss, loss of speech (aphonia) or vision, and dissociative seizures. The diagnosis rests on positive signs of inconsistency within the examination, shown to be present, not just on normal tests:

Midline splitting of sensation and la belle indifférence (apparent unconcern) are unreliable and should not be used.

Dissociative seizures

Dissociative seizures (psychogenic non-epileptic or functional seizures) resemble epilepsy or faints, and are often treated as epilepsy for years.

No single sign is decisive. The test is video-EEG capture of a typical episode. A raised prolactin 10 to 20 minutes after a generalised seizure supports epilepsy, but a normal level rules nothing out. About one in five patients with dissociative seizures also has epilepsy, though estimates vary widely between studies.

Dissociative amnesia, fugue and identity

• Dissociative amnesia is an inability to recall important personal information, usually about a stressful or traumatic event, too extensive for ordinary forgetting; usually patchy, rarely global. In a dissociative fugue the person also travels away, behaving outwardly normally, and may take on a new identity, with no memory of it afterwards. Epileptic automatisms, head injury, intoxication and transient global amnesia must be excluded.
• In dissociative identity disorder, two or more distinct personality states that take control in turn, with gaps in memory between them. It is rare, diagnosed far more in some countries and services than others. Rapid-cycling bipolar disorder and borderline personality disorder are differentials.
• Depersonalisation-derealisation disorder brings persistent or recurrent feelings of being detached from oneself, as an observer of one's own thoughts and actions, or that the world is unreal, dreamlike or flat, with insight preserved, unlike passivity in psychosis.
• Trance and possession disorders are involuntary states of altered identity, outside accepted cultural or religious practice.

Factitious disorder

The patient deliberately fabricates, induces or worsens illness: injecting contaminants, taking insulin, interfering with wounds, tampering with samples or inventing a history. Clues are a dramatic or inconsistent story, findings that defy explanation, many hospitals, eagerness for invasive procedures, and worsening just before discharge. The severe, wandering form (Munchausen syndrome) is commoner in men; non-wandering forms are commoner in women, often healthcare workers, and overlap with borderline personality disorder. In factitious disorder imposed on another (fabricated or induced illness), a carer, usually a parent, fabricates or induces illness in a child or other dependant.

04Diagnosis and management

Making the diagnosis

A functional diagnosis should be made confidently and on positive grounds: positive signs, a recognisable pattern, and features that do not fit disease. Follow-up studies show that later discovery of a disease that explains the symptoms is rare, about 5 per cent, similar to other diagnoses in neurology and psychiatry.

Principles for persistent bodily symptoms

1. 1

   Assess fully, once

   Read all the records, take a full history including what the patient believes and fears, examine, and screen for depression, anxiety and alcohol.
2. 2

   Explain

   Name the diagnosis, say what it is and is not, that it is common, real and can improve, and avoid implying that it is imagined. Write it down and copy the letter to the patient and every team.
3. 3

   One doctor, planned reviews

   One named clinician sees the patient at planned, regular intervals rather than whenever symptoms flare, and coordinates referrals.
4. 4

   Limit harm

   Investigate only new objective findings, stop unhelpful drugs, especially opioids and sedatives, and avoid operations aimed at symptoms alone.
5. 5

   Treat and rehabilitate

   Treat depression and anxiety; offer CBT, graded return to activity and, for pain, a low dose of a tricyclic such as amitriptyline or a pain programme.

Functional neurological disorder

Explanation by a neurologist who shows the patient the positive signs is the first treatment. Rehabilitation follows: physiotherapy that retrains automatic movement, occupational therapy, speech therapy for voice problems, and CBT where anxiety, avoidance or trauma are prominent. Wheelchairs and crutches can entrench disability. The evidence is modest: in the largest trials, specialist physiotherapy for functional motor disorder (Physio4FMD) did not beat community physiotherapy on the main outcome at 12 months, and CBT for dissociative seizures (CODES) did not reduce seizure frequency at 12 months, though several secondary outcomes improved.

In dissociative seizures, antiepileptic drugs are withdrawn under specialist care once epilepsy has been excluded. A prolonged dissociative seizure mistaken for status epilepticus can lead to large doses of benzodiazepines, intubation and intensive care, so a care plan for emergencies helps. Hypnosis and drug-assisted interviews (abreaction) are rarely used.

Dissociative disorders

Dissociative amnesia and fugue usually resolve over days to weeks with a safe setting, support and attention to the stress behind them. Dissociative identity disorder is treated with phased trauma-focused psychotherapy, starting with safety and stabilisation. Techniques that aim to recover forgotten memories, hypnosis among them, can create false memories. For depersonalisation-derealisation disorder, CBT has some support; SSRIs, sometimes with lamotrigine, have weak evidence.

Factitious disorder and malingering

There is no proven treatment for factitious disorder. The team agrees a plan, and a senior clinician raises the evidence calmly and without blame, offering continued care and psychiatric help; many patients leave. The aims are to stop needless investigations and treatments and to manage risk. In fabricated or induced illness in a child, the child's safety comes first: follow child protection procedures and involve safeguarding services before any challenge to the parent. Malingering is not treated as a disorder. Careful, factual documentation matters in both.

Consultation-liaison psychiatry

Consultation-liaison psychiatry, or psychological medicine, provides psychiatric care in the general hospital. In consultation, a psychiatrist assesses a patient at another team's request; in liaison, the team works within medical services, shaping how they care for patients. Almost every acute hospital in England with an emergency department now has a liaison psychiatry service, though fewer provide it around the clock, and in Germany psychosomatic medicine is a separate specialty.

of general hospital inpatients have a psychiatric disorder, twice the community rate

40per centof general hospital inpatients have a psychiatric disorder, twice the community rate

of patients on medical wards have delirium

20 to 30per centof patients on medical wards have delirium

of medical inpatients have a depressive disorder

10 to 20per centof medical inpatients have a depressive disorder

Physical disease and its treatment often cause psychiatric symptoms: depression with hypothyroidism, Cushing syndrome or steroids; anxiety with thyrotoxicosis, hypoglycaemia or phaeochromocytoma; psychosis with dopamine agonists or high-dose steroids. Prescribing needs care: lower doses in kidney and liver failure, QT prolongation with citalopram and antipsychotics in heart disease, bleeding with SSRIs and anticoagulants or NSAIDs, hyponatraemia with SSRIs in older people, and the interaction of lithium with NSAIDs, ACE inhibitors and thiazides.

05Epidemiology

Persistent bodily symptoms are among the commonest problems in primary care and every hospital specialty. The strict ICD-10 somatisation disorder is rare (lifetime about 0.2 per cent, five times commoner in women), but somatic symptom disorder, defined more broadly, may affect around 5 to 7 per cent of adults. Health anxiety affects men and women equally, with rates from under 1 to about 10 per cent depending on the setting.

Conversion disorder has a lifetime prevalence of about 3 to 6 per 1000 women, lower in men, and usually begins before 35; functional neurological disorder is one of the commoner diagnoses in neurology clinics. Dissociative seizures account for a substantial share of referrals to epilepsy centres with apparently drug-resistant epilepsy; most patients are young women, and diagnosis is often delayed for years. Up to half of people have transient depersonalisation at some time, 1 to 2 per cent chronically. Factitious disorder is rare but under-recognised.

06Prognosis

• Recent functional symptoms with a clear trigger usually resolve, in 70 to 90 per cent of acute conversion symptoms. Long-standing symptoms often persist: in one study of neurology inpatients with functional weakness or sensory loss, more than four in five still had symptoms 12 years later.
• Somatisation disorder runs a chronic, fluctuating course, and harm from tests, operations and drug dependence often outweighs the original symptoms. Dissociative seizures often continue for years, worse after a long delay to diagnosis.
• Dissociative amnesia and fugue usually recover within days to weeks; dissociative identity disorder and depersonalisation tend to be chronic.
• Factitious disorder has a poor prognosis; in fabricated or induced illness, children can be seriously harmed or die.
• Good prognostic signs are a short history, acceptance of the diagnosis, a clear precipitant, treated depression or anxiety, and no compensation dispute.