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Dissociative, Somatic, and Personality Disorders

Dissociative, Somatic, and Personality Disorders

6 min read Updated Apr 19, 2026

Three final disorder groups round out the chapter. They’re less common on the MCAT than schizophrenia or depression, but each appears in passages, and each has a distinct clinical picture.

Dissociative Disorders

Dissociation is a disconnect between consciousness, memory, identity, and perception. It can be a normal experience (daydreaming, highway hypnosis) but becomes a disorder when it’s severe or impairing.

Mixed-media collage portrait of a woman with eyes closed and red lips, hands pressed to her face. Jagged black-and-white paper shards radiate outward from her head as if her sense of self were fracturing apart
An artistic rendering of dissociation - a felt sense of fragmentation between thought, memory, identity, and perception. Mild dissociation is normal (daydreaming, highway hypnosis); severe or chronic dissociation defines disorders such as DID, dissociative amnesia, and depersonalization/derealization. Credit: Dyversions via Wikimedia Commons (CC0).

Dissociative Identity Disorder (DID)

Formerly called multiple personality disorder. Two or more distinct personality states (alters) that recurrently take control of behavior, with gaps in memory between states. Each alter may have its own name, voice, mannerisms, and even handwriting.

Strongly associated with severe childhood trauma (especially repeated abuse). The idea: the mind fragments as a defense, splitting unbearable experience into separate identities.

DID is rare and controversial in psychiatry - debated in terms of prevalence and the role of suggestion. The MCAT does test the basic concept.

Dissociative Amnesia

Inability to recall important autobiographical information, usually traumatic, not explained by ordinary forgetting. May be localized (specific event), selective (specific aspects), or generalized (entire life history). Can include dissociative fugue - purposeful travel with amnesia for past identity, sometimes adopting a new one.

Depersonalization/Derealization Disorder

Persistent or recurrent experiences of:

  • Depersonalization - feeling detached from your own thoughts, feelings, or body, as if watching yourself from outside.
  • Derealization - feeling the external world is unreal, dreamlike, visually distorted.

Reality testing remains intact (the person knows this isn’t real), distinguishing it from psychotic disorders.

The common thread: physical symptoms without adequate medical explanation, or disproportionate to any underlying medical condition.

Somatic Symptom Disorder

One or more distressing somatic symptoms, plus excessive thoughts, feelings, and behaviors regarding those symptoms. Persists for at least 6 months. The symptoms are real to the patient - often medically unexplained or only partially explained by findings.

Conversion Disorder (Functional Neurological Symptom Disorder)

Neurological symptoms (blindness, paralysis, seizures) that aren’t explained by any neurological disease. Historically called “hysterical conversion” - Freud thought psychic conflict was “converted” into physical symptoms.

Illness Anxiety Disorder (Formerly Hypochondriasis)

Preoccupation with having or acquiring a serious illness. Physical symptoms are minimal or absent. The person may perform excessive health-related checking, research symptoms obsessively, or avoid medical appointments out of fear of bad news.

Factitious Disorder

Deliberately producing or feigning symptoms for the purpose of assuming the sick role (no external reward). Distinct from malingering, where symptoms are faked for external gain (disability, drugs, avoiding work). Factitious disorder imposed on another (formerly Munchausen by proxy) involves inducing symptoms in someone else, typically a child.

Personality Disorders

Personality disorders are enduring patterns of inner experience and behavior that deviate markedly from cultural expectations, are pervasive and inflexible, begin by early adulthood, and cause distress or impairment. Ten specific disorders are organized into three clusters.

Cluster A: Odd or Eccentric

  • Paranoid. Distrustful, suspicious. Sees benign remarks as threats. Not psychotic.
  • Schizoid. Detached from social relationships. Limited emotional expression. “A loner” by preference.
  • Schizotypal. Eccentric thinking, speech, and behavior; magical thinking or unusual beliefs. Does not meet criteria for schizophrenia but shares some features.

Mnemonic: “weird.”

Cluster B: Dramatic, Emotional, or Erratic

  • Antisocial. Disregard for others’ rights; deception, impulsivity, aggression, lack of remorse. Was called psychopathy/sociopathy. Requires evidence of conduct disorder before age 15.
  • Borderline. Unstable relationships, self-image, and emotions. Intense fear of abandonment. Impulsivity (spending, sex, substance use, self-harm). Chronic feelings of emptiness. Suicidal/self-injurious behavior common.
  • Histrionic. Excessive emotionality and attention-seeking. Dramatic expression, sexually provocative behavior, shallow emotions.
  • Narcissistic. Grandiosity, need for admiration, lack of empathy. Exploits others, expects special treatment.

Mnemonic: “wild.”

Cluster C: Anxious or Fearful

  • Avoidant. Social inhibition, feelings of inadequacy, hypersensitivity to criticism. Wants relationships but is too afraid of rejection.
  • Dependent. Excessive need to be cared for. Submissive, clinging. Fears separation and inability to function alone.
  • Obsessive-compulsive personality disorder (OCPD). Preoccupation with order, perfectionism, and control. DIFFERENT from OCD - OCPD involves personality traits that feel ego-syntonic (the person thinks their rigidity is correct); OCD involves ego-dystonic obsessions/compulsions that distress the person.

Mnemonic: “worried.”

Treatment

Personality disorders are notoriously difficult to treat. Pharmacotherapy targets specific symptoms (mood, anxiety, psychosis) but doesn’t treat the underlying pattern. Dialectical behavior therapy (DBT), developed by Marsha Linehan, is the evidence-based psychotherapy for borderline personality disorder. Long-term psychotherapy can gradually shift rigid patterns but progress is slow.

What is the key distinction between DID and schizophrenia?
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DID (dissociative identity disorder) involves multiple distinct personality states with memory gaps between them - a dissociative disorder, often linked to childhood trauma. Schizophrenia involves psychotic symptoms (hallucinations, delusions, disorganized thought) and one identity. Popular culture often confuses the two, but they are unrelated.
Distinguish somatic symptom disorder, conversion disorder, illness anxiety disorder, and factitious disorder.
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Somatic symptom disorder: real distressing symptoms + excessive concern. Conversion disorder: neurological-like symptoms with no medical basis. Illness anxiety disorder: preoccupation with having/getting an illness, minimal symptoms. Factitious disorder: deliberately producing/faking symptoms to assume sick role (malingering does so for external gain).
A patient has unstable relationships, intense fear of abandonment, chronic emptiness, and self-harming behavior. Which personality disorder?
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Borderline personality disorder (Cluster B). Evidence-based psychotherapy is DBT (dialectical behavior therapy), developed by Marsha Linehan.
What distinguishes OCD from OCPD?
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OCD: obsessions and compulsions that are ego-dystonic (the person finds them distressing and irrational). OCPD: pervasive personality pattern of rigidity, perfectionism, and control that is ego-syntonic (the person thinks their approach is correct and doesn't see a problem).
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