Difficulty: Intermediate | Prerequisites: Introduction to abnormal psychology, DSM-5 classification basics
Somatic symptom and related disorders sit at the intersection of mind and body. They describe conditions where physical symptoms either lack a full medical explanation or where psychological factors drive an excessive response to those symptoms. This cluster of disorders replaced older categories like "somatoform disorders" and "hypochondriasis" in the DSM-5, reflecting a shift away from the idea that symptoms must be medically unexplained and towards a focus on how the person responds to their symptoms. If you are coming in cold, you will want to be comfortable with the general structure of DSM-5 diagnostic criteria and the difference between signs (observable) and symptoms (reported by the patient).
These disorders involve physical complaints that are either not fully explained by a medical condition or are accompanied by disproportionate psychological distress. The four main disorders in this group are Somatic Symptom Disorder, Illness Anxiety Disorder, Conversion Disorder, and Factitious Disorder. Each has distinct diagnostic criteria, but they share a common thread: the relationship between psychological processes and physical experience.
Somatic Symptom Disorder (SSD)
An excessive focus on one or more physical symptoms (such as pain or fatigue) that causes significant emotional distress and disruption to daily life. The key feature is not the symptoms themselves, but the disproportionate thoughts, feelings, or behaviours they produce.
Think of it as: the problem is less about the symptom and more about how consumed the person becomes by it.
Illness Anxiety Disorder (IAD)
A preoccupation with having or acquiring a serious illness, despite having mild or no somatic symptoms. Formerly known as hypochondriasis.
In simple terms, this means the person is anxious about being ill, rather than distressed by specific physical complaints.
Conversion Disorder (Functional Neurological Symptom Disorder)
Neurological symptoms, such as paralysis, blindness, or seizures, that are inconsistent with any recognised neurological or medical condition. The symptoms are real to the patient but have no organic cause.
Think of it as: the body expresses psychological distress through neurological-looking symptoms that do not match any known disease.
Factitious Disorder
Deliberate falsification or induction of physical or psychological symptoms, associated with deception, in the absence of obvious external rewards like financial gain.
In simple terms, the person fakes or causes illness not for material benefit, but to occupy the role of a patient.
Astasia-abasia
Difficulty standing or walking that is not explained by neurological disease. A classic presentation of conversion disorder.
Psychogenic nonepileptic seizures (PNES)
Seizure-like episodes that are not caused by abnormal electrical activity in the brain. They fall under conversion disorder.
Secondary gain
An indirect benefit a person receives from being ill, such as attention, sympathy, or avoidance of responsibilities. Relevant to understanding what maintains symptoms in several of these disorders.
Maladaptive avoidance
Avoiding situations (such as medical appointments) in a way that maintains or worsens the disorder, rather than helping.
One or more somatic symptoms that are distressing or significantly disrupt daily life
Excessive thoughts, feelings, or behaviours related to those symptoms, shown by at least one of the following:
Disproportionate and persistent thoughts about how serious the symptoms are
Persistently high anxiety about health or symptoms
Excessive time and energy devoted to the symptoms or health concerns
The symptomatic state is persistent, typically lasting more than six months
A medical condition may or may not be present; the diagnosis hinges on the psychological response, not the absence of a medical explanation
Case illustration: Jada, a woman in her 30s with joint swelling and chronic infections, was deeply engaged with healthcare professionals and services. Her presentation exemplifies the excessive health-related behaviour that defines SSD.
Preoccupation with having or acquiring a serious illness
Somatic symptoms are absent or, if present, mild in intensity
High anxiety about health and easily alarmed about personal health status
Excessive health-related behaviours (e.g. body checking for signs of illness) or maladaptive avoidance (e.g. avoiding doctors)
The preoccupation persists for at least six months but may shift between different feared illnesses
Two behavioural subtypes:
Care-seeking type: frequent medical visits, reassurance-seeking
Care-avoidant type: avoids medical settings out of fear of confirmation
Case illustration: Leinani was less concerned with specific physical symptoms and more consumed by the idea of being ill, a hallmark of IAD.
One or more symptoms of altered voluntary motor or sensory function
Clinical findings provide evidence of incompatibility between the symptom and recognised neurological or medical conditions
The symptom is not better explained by another medical or mental disorder
Common presentations:
Paralysis or weakness
Blindness or visual disturbance
Aphonia (difficulty speaking)
Psychogenic nonepileptic seizures
Pathophysiology: psychological stress or conflict manifests as physical symptoms. Traumatic events and repression of anxiety can result in these conversions
Case illustration: Eloise experienced difficulty walking, diagnosed as astasia-abasia, a classic conversion disorder symptom.
Falsification of physical or psychological symptoms, or self-inflicted injury, associated with deception
The person presents themselves as ill, impaired, or injured
Deceptive behaviour persists even without obvious external rewards
Distinguished from malingering by the absence of external incentive (malingering involves clear external gain, such as avoiding work or obtaining compensation)
Can be imposed on self or on another person (formerly known as Munchausen syndrome or Munchausen by proxy)
SSD vs. IAD: SSD involves distressing physical symptoms with disproportionate response. IAD involves preoccupation with illness despite minimal or no symptoms. The focus in SSD is on the symptoms; in IAD, on the feared disease.
Conversion Disorder vs. Factitious Disorder: conversion symptoms are not deliberately produced. Factitious symptoms are intentionally faked or induced.
Factitious Disorder vs. Malingering: factitious disorder lacks external incentive. Malingering is driven by tangible gain (and is not classified as a mental disorder).
These diagnoses are common in general medical settings, not just psychiatric clinics. A GP seeing a patient who returns repeatedly with unexplained complaints, or an A&E doctor encountering seizures that do not match epileptic patterns on EEG, is encountering this diagnostic territory in practice. Recognising these disorders early prevents unnecessary medical procedures and helps direct the patient towards appropriate psychological support.
Students often think somatic symptom disorder requires that symptoms have no medical explanation. It does not. A person can have a diagnosed medical condition and still meet criteria for SSD if their psychological response is disproportionate.
Students frequently confuse illness anxiety disorder with somatic symptom disorder. The distinguishing factor is symptom burden: IAD involves minimal or no physical symptoms, while SSD involves prominent ones.
Conversion disorder symptoms are sometimes assumed to be "faked." They are not. The patient experiences the symptoms as real and is not consciously producing them. Factitious disorder is the diagnosis where deliberate fabrication is present.
Malingering is sometimes grouped with factitious disorder. Malingering is not a mental disorder; it is intentional deception for external gain.
⚠️ Know the difference between SSD and IAD. This is a commonly tested distinction. SSD = prominent symptoms + disproportionate response. IAD = minimal symptoms + preoccupation with illness.
⚠️ Conversion disorder symptoms are genuine to the patient, not deliberately produced. Do not confuse with factitious disorder.
⚠️ Factitious disorder is distinguished from malingering by the absence of external incentive.
⚠️ The DSM-5 moved away from requiring that symptoms be "medically unexplained." The focus is now on the excessive psychological response.
⚠️ The six-month duration criterion applies to both SSD and IAD.
True or false: Somatic Symptom Disorder can only be diagnosed if no medical condition is found to explain the symptoms.
Fill in the blank: Illness Anxiety Disorder was formerly known as __________.
True or false: In conversion disorder, the patient is deliberately faking their symptoms.
Fill in the blank: The key difference between factitious disorder and malingering is the absence of __________ in factitious disorder.
True or false: In IAD, the preoccupation with illness must persist for at least six months.
Q: What is the primary distinction between Somatic Symptom Disorder and Illness Anxiety Disorder?
A: SSD involves one or more distressing somatic symptoms with a disproportionate psychological response. IAD involves preoccupation with having or acquiring a serious illness despite minimal or no somatic symptoms. The focus in SSD is on the symptoms themselves; in IAD, it is on the feared disease.
Q: A patient presents with paralysis in one leg, but neurological examination and imaging reveal no organic cause. What disorder should be considered, and why?
A: Conversion disorder (functional neurological symptom disorder). The symptom is neurological in appearance but incompatible with any recognised neurological condition, which is the defining feature of this diagnosis.
Q: How does factitious disorder differ from malingering?
A: In factitious disorder, the person falsifies symptoms without obvious external incentive such as financial gain or avoiding responsibility. In malingering, deception is motivated by a clear external reward. Malingering is not classified as a mental disorder.
Q: A patient has a diagnosed autoimmune condition but spends most of their day researching symptoms online, visits multiple specialists weekly, and experiences severe anxiety about their health that is out of proportion to their medical findings. Could they meet criteria for SSD?
A: Yes. SSD does not require the absence of a medical condition. The diagnosis centres on the excessive and disproportionate thoughts, feelings, and behaviours related to the symptoms, not on whether a medical explanation exists.
Q: Name two behavioural subtypes of Illness Anxiety Disorder.
A: Care-seeking type (frequent medical visits, reassurance-seeking) and care-avoidant type (avoidance of medical settings due to fear of confirmation).
This material connects to mood and anxiety disorders, because health anxiety and somatic preoccupation often co-occur with generalised anxiety and depression. It also links to trauma and stressor-related disorders, since conversion disorder frequently follows traumatic events. Understanding the biopsychosocial model is essential here, as these disorders illustrate how psychological processes produce or amplify physical experience.
somatic symptom disorder, SSD, illness anxiety disorder, IAD, hypochondriasis, conversion disorder, functional neurological symptom disorder, factitious disorder, Munchausen syndrome, Munchausen by proxy, malingering, psychogenic nonepileptic seizures, PNES, astasia-abasia, aphonia, secondary gain, DSM-5 somatic disorders, somatoform disorders, health anxiety, medically unexplained symptoms, abnormal psychology, University of Florida