Behavioral Health

Delusional disorder: subtypes and management

Clinical Overview and When to Suspect Delusional Disorder

— Criterion A: one or more delusions ≥1 month

— Criterion B: Criterion A for schizophrenia has never been met (no prominent hallucinations, disorganized speech, grossly disorganized behavior, or negative symptoms)

— Criterion C: functioning not markedly impaired, behavior not bizarre

— Criterion D: if mood episodes occurred, they were brief relative to delusional periods

— Criterion E: not due to substance/medical condition or better explained by another disorder (e.g., BDD, OCD)

— Middle-aged or older outpatient brought in by family for a fixed, non-bizarre belief (cheating spouse, being followed, parasitic infestation, secret admirer)

— Patient is otherwise dressed, employed, oriented, and conversation is coherent outside the topic

— Repeated visits to dermatology, ID, ENT, or law enforcement seeking validation

— No prior psychiatric history; insight is poor to absent

Definition (DSM-5-TR): Presence of ≥1 delusion for ≥1 month, in a person whose functioning is not markedly impaired and whose behavior is not obviously bizarre outside the delusional theme.

Epidemiology: lifetime prevalence ~0.2%; mean onset middle-to-late adulthood (40s–60s); slight female predominance overall but jealous type more common in men.

When to suspect on Step 3:

Risk factors: social isolation, immigration, sensory impairment (especially hearing loss in late-onset cases), family history of schizophrenia spectrum, head trauma.

Board pearl: The single most useful discriminator from schizophrenia on a vignette is preserved psychosocial functioning plus absence of hallucinations and disorganization. If the stem mentions auditory hallucinations as prominent, it is not delusional disorder.

Key distinction: "Non-bizarre" means the belief could plausibly happen in real life (being poisoned by a coworker = non-bizarre; organs replaced by aliens = bizarre → favors schizophrenia). Bizarre content does not exclude delusional disorder per DSM-5-TR, but on exams non-bizarre content remains the classic cue.

Step 3 management entry point: Confirm duration ≥1 month, screen for substances (stimulants, steroids), rule out delirium/dementia, then refer for outpatient psychiatry with antipsychotic trial as cornerstone.

Presentation Patterns and Key History

— Erotomanic: belief that a person of higher status (celebrity, physician, politician) is secretly in love with the patient; letters, calls, stalking. More common in women.

— Grandiose: inflated worth, power, identity, or special relationship to a deity/famous person. Distinguish from mania by absence of mood symptoms.

— Jealous (conjugal/Othello syndrome): unshakeable belief partner is unfaithful; checking phones, hiring investigators. Associated with alcohol use disorder and intimate-partner violence risk.

— Persecutory (most common): being conspired against, poisoned, spied on. Patients file lawsuits, complaints, contact police.

— Somatic: body infested, malodorous, or deformed. Delusional parasitosis (Ekbom syndrome) → "matchbox sign," skin specimens brought to derm.

— Mixed: more than one theme, none predominant.

— Unspecified: dominant delusion can't be clearly determined (e.g., Capgras, Fregoli without other features).

— Onset, content stability, time course (must be ≥1 month)

— Functional status: still working, paying bills, maintaining hygiene?

— Collateral from family — patients underreport

— Substance review: methamphetamine, cocaine, cannabis, anabolic steroids, levodopa, high-dose corticosteroids

— Medical: CNS lesions, neurosyphilis, HIV, B12 deficiency, thyroid disease, temporal lobe epilepsy

— Sensory: hearing or visual loss (late-paraphrenia presentations)

— Safety: homicidal ideation toward "the lover," "the cheater," or "the persecutor"; access to firearms

Seven DSM-5-TR subtypes — memorize the trigger phrases:

History essentials on Step 3 vignettes:

Board pearl: A 55-year-old man convinced his wife is having an affair despite no evidence, with heavy alcohol use → jealous type + screen aggressively for IPV and weapons.

Key distinction: Erotomania in delusional disorder is fixed and monothematic; in mania it is expansive, mood-congruent, and episodic with pressured speech and decreased sleep.

Step 3 management: Always document a violence risk assessment in jealous and persecutory types — this is both clinical and medicolegal protection.

Physical Exam Findings and Mental Status Assessment

— Somatic subtype may show excoriations, prurigo nodularis, ulcers from picking, or self-applied topical agents

— Jealous subtype: signs of alcohol use (telangiectasias, hepatomegaly, elevated GGT)

— Behavior: engaged, often articulate; can be guarded if persecutory

— Speech: normal rate, rhythm, prosody — not pressured, not disorganized

— Mood/affect: congruent to delusional content (angry when discussing "the cheater"), otherwise reactive and full

— Thought process: linear and goal-directed outside the delusional theme — a hallmark

— Thought content: fixed false belief; absent or minimal hallucinations (tactile in parasitosis or olfactory in somatic type may occur but are not prominent)

— Cognition: intact orientation, attention, memory, executive function

— Insight: poor; judgment impaired regarding the delusion only

— Suicidality/homicidality: must be explicitly assessed

— Cranial nerves, gait, focal deficits → rule out frontal/temporal lesion

— Cognitive screen: MoCA preferred over MMSE for executive dysfunction

— Check hearing and vision — uncorrected deficits drive late-onset psychotic symptoms

— Tachycardia, hypertension, tremor → consider stimulant intoxication or hyperthyroidism

— Fever, neck stiffness, altered consciousness → this is delirium, not delusional disorder

General appearance: typically well-groomed, cooperative, age-appropriate dress — a deliberate exam contrast to schizophrenia.

Mental Status Exam pattern:

Neurologic exam (mandatory in new late-life presentation):

Vitals and systemic exam:

Board pearl: Preserved cognition with isolated fixed delusion in a 70-year-old with hearing aids in the drawer → check audiogram; correcting presbycusis can reduce paranoid ideation.

Key distinction: In delirium, attention fluctuates and orientation is impaired; in delusional disorder, sensorium is clear. If a vignette says "waxing and waning attention," abandon the delusional disorder diagnosis.

Step 3 management: Document capacity for specific decisions (e.g., refusing medical workup) — capacity is decision-specific and is often preserved despite delusions outside that decision's domain.

Diagnostic Workup — Initial Labs, Imaging, and Screening

— CBC, CMP (electrolytes, calcium, glucose, hepatic, renal)

— TSH (hyper- or hypothyroidism can mimic)

— Vitamin B12, folate

— HIV and RPR/treponemal-specific test — neurosyphilis is the classic missed cause in board questions

— Urinalysis (UTI in elderly → delirium mimic)

— Urine toxicology: amphetamines, cocaine, cannabinoids, PCP

— Pregnancy test in women of childbearing age before antipsychotic initiation

— Ceruloplasmin, 24-hr urine copper if <40 yo with neuropsychiatric symptoms → Wilson disease

— ANA, anti-NMDA receptor antibodies if subacute psychosis with autonomic instability, dyskinesias, seizures (autoimmune encephalitis)

— Heavy metals (lead, mercury) for occupational exposure

— Cortisol/dexamethasone suppression if Cushingoid features

— EEG if any episodic stereotyped psychotic episodes → temporal lobe epilepsy

— MRI brain (preferred over CT) for: first-episode psychosis after age 40, focal neuro deficits, atypical features, rapid cognitive decline, history of head trauma, treatment resistance

— Look for frontal/temporal lesions, strokes, tumors, NPH, white matter disease

Delusional disorder is a clinical diagnosis — labs and imaging are to exclude secondary causes, not to confirm.

First-tier outpatient workup (any new psychotic presentation):

Targeted additions by clinical context:

Neuroimaging — when to order:

ECG before antipsychotic: baseline QTc is essential before starting most antipsychotics (haloperidol, ziprasidone, iloperidone are particular offenders).

Board pearl: A 60-year-old with new-onset persecutory delusions, hyporeflexia, and macrocytic anemia → check B12 before reaching for risperidone.

Key distinction: Acute delirium workup emphasizes infection and metabolic derangement; delusional disorder workup emphasizes chronic secondary causes (neurosyphilis, B12, thyroid, structural lesions).

Step 3 management: Order MRI brain, TSH, B12, HIV, RPR, UDS, CMP, CBC, ECG, and pregnancy test as the standard new-onset psychosis panel in middle-aged/older adults — the question often hinges on which one was skipped.

Diagnostic Workup — Confirmatory and Differential-Narrowing Studies

— DSM-5-TR criteria checklist; document delusion duration explicitly

— Collateral history from family, employer, or PCP — patients minimize

— Review prior records for episodic mood symptoms (rules in mood disorder with psychotic features)

— Validated tools (rarely tested but legitimate): PANSS, BPRS for symptom tracking; SAPS captures delusional severity

— Indicated when cognitive impairment is suspected and clinical exam is equivocal

— Distinguishes dementia with delusions (executive and memory deficits) from delusional disorder (preserved cognition)

— Frontotemporal dementia behavioral variant can present with paranoid delusions and disinhibition — neuropsych + MRI atrophy pattern clarifies

— Reserve for suspected CNS infection, autoimmune encephalitis, or paraneoplastic syndrome

— Send CSF for cell count, protein, glucose, VDRL, anti-NMDA receptor antibodies, oligoclonal bands, viral PCR

— 24-hr urine free cortisol or late-night salivary cortisol if Cushing suspected

— Free T4 and TSH receptor antibodies for Graves disease

— Time-locked: symptoms began with drug initiation and resolve with discontinuation

— Common culprits: corticosteroids, levodopa, dopamine agonists, anticholinergics, interferon, isotretinoin, varenicline, methylphenidate, amphetamines

Structured psychiatric assessment:

Neuropsychological testing:

Lumbar puncture:

Polysomnography: if narcolepsy or REM behavior disorder is on the table (hypnagogic hallucinations can be misread as psychosis).

Endocrine confirmation:

Genetic testing: not routine; consider in early-onset, family history of Huntington (chorea + psychiatric prodrome).

Drug-induced delusions confirmation:

Board pearl: New persecutory delusions in a Parkinson patient → reduce dopaminergic medications first, then add pimavanserin or low-dose quetiapine/clozapine; avoid first-gen antipsychotics that worsen motor symptoms.

Key distinction: Delusional disorder requires that symptoms are not better explained by substance/medical condition — this is a diagnostic-criterion-level rule-out, not a "consider also" item.

Step 3 management: Document the specific etiology workup that was negative before assigning the delusional disorder diagnosis — surveyors and the test both expect this.

Risk Stratification and First-Line Management Logic

— Step 1: Is there acute danger to self or others? Homicidal ideation toward perceived persecutor or cheating partner, access to weapons, recent escalation → emergency psychiatric evaluation, possible involuntary hold

— Step 2: Is the patient able to maintain basic functioning (food, shelter, medical care)? If not → inpatient

— Step 3: Is a secondary cause identified and reversible (B12, thyroid, drug-induced)? → treat that first

— Step 4: Otherwise → outpatient psychiatric management with antipsychotic + psychotherapy

— Do not directly confront or challenge the delusion early — this destroys rapport

— Do not collude or agree with the delusion — undermines integrity and worsens trust over time

— Use neutral curiosity: "Help me understand how this has been affecting your life"

— Focus on distress and functional impairment the delusion causes, not the truth of the belief

— Frame medication as helping with stress, sleep, or anxiety if the patient rejects "psychotic" framing

— Antipsychotic monotherapy — first-line pharmacologic

— CBT for psychosis (CBTp) — reduces conviction and distress

— Supportive psychotherapy and family education

— Address comorbidities: alcohol use (especially jealous type), depression, anxiety

— Better outcomes: female sex, acute onset, identifiable precipitant, younger onset, persecutory or somatic types

— Worse outcomes: chronicity, social isolation, severe paranoia, jealous type, comorbid SUD

Decision framework on initial encounter:

Outpatient is the default — most delusional disorder patients are managed ambulatorily, which is a recurrent Step 3 testing point.

Therapeutic alliance is the rate-limiting step:

Treatment modalities (combination preferred):

Prognostic factors:

Board pearl: Adherence is the central long-term challenge — by definition the patient does not believe they are ill. Plan for long-acting injectable antipsychotics early if non-adherence is anticipated.

Step 3 management: First visit deliverables — safety assessment, secondary-cause workup ordered, antipsychotic started at low dose, follow-up in 1–2 weeks, family psychoeducation provided, written safety plan if any violence risk.

Pharmacotherapy — First-Line Antipsychotic Regimens

— Risperidone 0.5–1 mg/day, titrate to 2–6 mg — most commonly tested first-line

— Olanzapine 5 mg/day → 10–20 mg; watch metabolic effects

— Aripiprazole 5–10 mg → 15–30 mg; lower metabolic burden, useful in young patients

— Quetiapine 50 mg → 300–600 mg; useful in Parkinson-related psychosis at low dose

— Pimozide historically favored for delusional parasitosis but largely supplanted by SGAs due to QT prolongation and EPS; still high-yield as a board association

— Start low, go slow — adherence collapses with early side effects

— Allow 4–6 weeks at therapeutic dose before declaring failure

— If partial response → optimize dose; if no response → switch agent

— Two failed adequate trials = treatment-resistant → consider clozapine

— Metabolic syndrome (olanzapine > quetiapine > risperidone > aripiprazole > ziprasidone): weight, BP, fasting glucose, lipids, HbA1c at baseline, 12 weeks, then annually

— EPS (risperidone, haloperidol): akathisia, parkinsonism, tardive dyskinesia (AIMS every 6 months)

— Hyperprolactinemia (risperidone, paliperidone): galactorrhea, amenorrhea, sexual dysfunction

— QTc prolongation (ziprasidone, iloperidone, pimozide, haloperidol IV): baseline + repeat ECG

— Sedation, orthostasis: especially in elderly

— Neuroleptic malignant syndrome: rigidity, hyperthermia, autonomic instability, elevated CK

— SSRI if comorbid depression or significant anxiety; some evidence for SSRIs alone in somatic-type and body-dysmorphic-spectrum presentations

— Benzodiazepine short-term for severe agitation, not maintenance

Class: second-generation antipsychotics (SGAs) are first-line based on tolerability; evidence base in delusional disorder is limited (mostly extrapolated from schizophrenia trials and case series), but expert consensus and Step 3 favor SGAs.

Preferred agents and starting doses (outpatient):

Titration principles:

Adverse effects to monitor:

Adjunctive medications:

Board pearl: Pimozide for delusional parasitosis is the classic boards association — but in modern practice risperidone or olanzapine is preferred and equally testable.

Step 3 management: Order baseline weight, waist, BP, fasting lipids, glucose, HbA1c, ECG, prolactin (if symptomatic), AIMS — then write the prescription.

Expanded Pharmacology — Treatment Resistance, LAIs, and Subtype-Specific Choices

— Defined as failure of ≥2 adequate antipsychotic trials (different agents, 6 weeks each, therapeutic dose, confirmed adherence)

— Clozapine is the evidence-based next step

— Requires REMS enrollment, ANC monitoring weekly × 6 months, biweekly × 6 months, then monthly

— Hold for ANC <1000; discontinue and never rechallenge if severe neutropenia (<500) unless benign ethnic neutropenia documented

— Major adverse effects: agranulocytosis, myocarditis (first 4–8 weeks — check troponin, CRP, ECG if tachycardic/febrile), seizures (dose-dependent), metabolic syndrome, constipation/ileus, sialorrhea

— Indicated when non-adherence is the failure mode — common in delusional disorder by definition

— Paliperidone palmitate (monthly, 3-monthly, 6-monthly formulations) — no oral overlap required for some loading regimens

— Aripiprazole monohydrate or lauroxil — lower metabolic burden

— Risperidone microspheres (biweekly) or subcutaneous risperidone

— Document a discussion: LAIs improve outcomes but require trust-building; do not coerce

— Somatic (delusional parasitosis): risperidone, olanzapine, aripiprazole; historical pimozide

— Jealous type with alcohol use: treat alcohol use disorder concurrently (naltrexone or acamprosate), antipsychotic, IPV safety planning

— Persecutory type: risperidone or olanzapine, CBTp adjunct

— Erotomanic: antipsychotic; legal consultation if stalking the object of delusion (mandatory reporting may apply in some jurisdictions if there is a credible threat)

— Parkinson-associated psychosis: pimavanserin (selective 5-HT2A inverse agonist, no D2 blockade), or low-dose quetiapine/clozapine; avoid haloperidol and risperidone

— CYP2D6 inhibitors (fluoxetine, paroxetine, bupropion) raise risperidone/aripiprazole levels

— Smoking induces CYP1A2 → lowers olanzapine and clozapine levels (relevant on hospitalization when patients quit abruptly)

Treatment-resistant delusional disorder:

Long-acting injectables (LAIs):

Subtype-tailored choices:

Drug interactions to flag:

CCS pearl: For a hospitalized patient newly started on clozapine who develops fever and tachycardia in week 3 — order troponin, CRP, ECG, echo for myocarditis before assuming infection; discontinue clozapine if confirmed.

Special Populations — Elderly and Renal/Hepatic Impairment

— Often called late paraphrenia historically

— Strongly associated with sensory deficits (hearing loss especially), social isolation, and mild cognitive impairment

— Persecutory type predominates ("neighbors are pumping gas into my apartment")

— Always rule out dementia, delirium, depression with psychotic features, medication effect before assigning

— Black box warning: increased mortality in elderly patients with dementia-related psychosis — applies to all antipsychotics

— Use the lowest effective dose, shortest duration, document risk/benefit and surrogate discussion

— Preferred: quetiapine (low EPS, useful in Lewy body/Parkinson), risperidone at 0.25–0.5 mg, aripiprazole low dose

— Avoid: olanzapine (metabolic, anticholinergic), high-potency typicals

— Monitor for falls, orthostasis, anticholinergic delirium, QT prolongation, stroke risk

— Paliperidone is renally cleared — reduce dose if CrCl <50; avoid if CrCl <10

— Risperidone active metabolite is paliperidone → also requires reduction in renal failure

— Olanzapine, quetiapine, aripiprazole, clozapine are hepatically metabolized — generally do not require renal adjustment but start lower

— Reduce starting dose of most SGAs by ~50%

— Avoid chlorpromazine (cholestasis), use caution with clozapine (hepatotoxicity, agranulocytosis risk compounded)

— Check LFTs at baseline and periodically

— Anticholinergics, benzodiazepines, opioids, sedating antihistamines compound cognitive impairment and fall risk

— Use Beers Criteria to deprescribe

Late-onset delusional disorder (≥60 years):

Antipsychotic prescribing in elderly:

Renal impairment:

Hepatic impairment:

Polypharmacy review is essential in elderly:

Board pearl: A 78-year-old in assisted living with paranoid delusions and cognitive deficits → this is most likely major neurocognitive disorder with psychotic features, not delusional disorder. Treat the dementia, address environment, use antipsychotic only if behavior endangers patient/others, with informed surrogate consent.

Step 3 management: Before prescribing antipsychotic in elderly, document: baseline cognition, fall risk, ECG QTc, postural BP, medication reconciliation, and goals-of-care conversation with patient and family.

Special Populations — Pregnancy, Postpartum, and Younger Adults

— Untreated psychosis carries substantial risk: poor prenatal care, self-neglect, substance use, suicide, harm to fetus from delusion content (e.g., denial of pregnancy)

— Continue antipsychotic if needed for stability — abrupt discontinuation often worsens outcomes

— Preferred agents: haloperidol, olanzapine, quetiapine, risperidone, aripiprazole have the most safety data; no agent is risk-free

— Avoid new starts with paliperidone LAI in pregnancy without specialist input

— Third-trimester exposure: monitor neonate for EPS, withdrawal, sedation, feeding difficulty (Poor Neonatal Adaptation Syndrome)

— Folate 4 mg/day if on any psychotropic; standard prenatal otherwise

— Coordinate with OB and neonatology; document shared decision-making

— Most antipsychotics enter breast milk in small amounts

— Olanzapine, quetiapine, risperidone generally compatible

— Avoid clozapine (agranulocytosis risk in infant) and lithium if used adjunctively

— Monitor infant for sedation, weight gain, EPS

— Distinguish delusional disorder from postpartum psychosis — the latter is acute, mood-laden, with rapid onset within 2–4 weeks of delivery, and is a psychiatric emergency requiring inpatient admission and consideration of ECT

— Postpartum psychosis is associated with bipolar disorder, not delusional disorder

— Delusional disorder is uncommon in this age group; first reconsider schizophrenia, schizophreniform, brief psychotic disorder, substance-induced

— Screen for cannabis (especially high-potency), synthetic cannabinoids, stimulants, hallucinogens

— Consider autism spectrum with overvalued ideas (not delusions)

— Address fertility, weight, and metabolic concerns proactively; aripiprazole or lurasidone are reasonable starts

Pregnancy:

Breastfeeding:

Postpartum considerations:

Younger adults (18–35):

Adolescents: Delusional disorder is rare; pursue thorough developmental and trauma history; consult child psychiatry.

Board pearl: A 25-year-old new mother with sudden-onset paranoid delusions about her baby being replaced → this is postpartum psychosis, requires hospitalization, and is not delusional disorder regardless of content.

Step 3 management: For pregnant patients with delusional disorder, schedule monthly joint psychiatric/OB visits, share medication list with pediatrics before delivery, and plan postpartum follow-up at 1–2 weeks.

Complications and Adverse Outcomes

— Violence: jealous and persecutory types carry meaningful risk to specific targets (partner, perceived persecutor); homicide in Othello syndrome is a recognized association

— Suicide: lifetime risk elevated, particularly with comorbid depression, persecutory delusions, somatic distress, and loss of social support

— Stalking and legal entanglement: erotomanic type — restraining orders, arrests; defendant may have impaired capacity

— Isolation: progressive withdrawal as family becomes incorporated into delusional system

— Job loss, housing instability, financial ruin from lawsuits, hiring investigators, or paying "experts"

— Somatic type: self-injury from picking, application of caustic agents, repeated unnecessary biopsies, antibiotics, antiparasitics

— Persecutory type: refusal of medical care due to belief providers are part of conspiracy → untreated chronic disease

— Jealous type: heavy alcohol use → liver disease, withdrawal, nutritional deficiency

— Metabolic syndrome, T2DM, dyslipidemia, weight gain (SGAs)

— Cardiovascular: QT prolongation, sudden cardiac death (rare, dose-related)

— EPS, tardive dyskinesia — TD risk ~5%/year on FGAs, lower on SGAs

— NMS: rare but lethal — discontinue antipsychotic, supportive care, dantrolene/bromocriptine

— Clozapine-specific: agranulocytosis, myocarditis, seizures, ileus, sialorrhea

— Hyperprolactinemia → bone loss over years; check DXA if prolonged

— Anticholinergic burden → cognitive decline, urinary retention, constipation

— Close relative (often spouse/parent) adopts the delusion

— Treatment: separation from index patient + treat index; secondary case often resolves without antipsychotic

Behavioral and social complications:

Medical complications:

Treatment-related complications:

Folie à deux (shared psychotic disorder, now "delusional symptoms in partner of individual with delusional disorder"):

Mortality: all-cause mortality elevated vs general population, driven by cardiovascular disease, suicide, and accidents.

Board pearl: A wife of a man with jealous delusional disorder begins endorsing the same conspiracy → separate them first; her symptoms may remit without medication. This is the classic folie à deux vignette.

Step 3 management: At every visit document weight, BP, AIMS (≥q6mo), labs annually, suicide and violence screen, and adherence assessment.

When to Escalate — Inpatient, Consultation, and Emergency Triage

— Active homicidal ideation with identified target, plan, or means (especially jealous and persecutory types)

— Suicidal ideation with intent or plan

— Grave disability: unable to feed, clothe, or shelter self due to delusion (refusing food because "poisoned")

— Acute decompensation with disorganization or impaired reality testing extending beyond the delusional theme

— Suspected secondary cause requiring urgent workup (autoimmune encephalitis, CNS infection, mass)

— Severe self-injury from somatic delusions (extensive excoriations, ingestion of harmful substances)

— Danger to self, danger to others, or grave disability due to a mental illness

— Document the specific behavior, specific threat, and causal link to psychosis

— Use the least restrictive setting that ensures safety

— When a patient communicates a serious threat against an identifiable victim, the clinician has a duty to protect — options include warning the intended victim, notifying law enforcement, hospitalization, or intensifying treatment

— Jurisdiction-specific (Tarasoff applies in California; analogous statutes exist elsewhere) — but Step 3 expects you to act

— Psychiatry — confirmation, medication, capacity assessment

— Neurology — focal deficits, atypical presentation, seizures

— Social work — safety planning, IPV resources, housing

— Legal/risk management — if duty-to-warn is triggered, capacity for refusing treatment is contested, or court-ordered treatment is sought

— Ethics — when forced medication or guardianship is being considered

— Worsening symptoms despite adherence → switch agent or add CBTp

— New comorbid depression → add SSRI, reassess suicide risk

— Family burnout → arrange respite, family therapy

Indications for emergency psychiatric evaluation / inpatient admission:

Involuntary hold criteria (state-specific but common features):

Tarasoff and duty to protect:

Consultations to order:

Outpatient escalation triggers (without immediate hospitalization):

CCS pearl: Patient with persecutory delusions says "If I see my landlord, I'll shoot him" and admits to owning a firearm → admit involuntarily, notify landlord and police (duty to protect), document the chain of decision-making. Discharging this patient is the wrong answer regardless of "good insight" elsewhere.

Key Differentials — Within the Psychotic Spectrum

— Requires ≥6 months total duration including prodrome, with ≥1 month of active-phase symptoms

— Two or more of: delusions, hallucinations, disorganized speech, grossly disorganized/catatonic behavior, negative symptoms — and at least one must be delusions, hallucinations, or disorganized speech

— Marked functional decline in work, relationships, or self-care

— Differentiator: delusional disorder lacks prominent hallucinations, disorganization, and functional decline

— Same symptoms as schizophrenia but duration 1–6 months

— Function may or may not decline

— Differentiator: meets full Criterion A of schizophrenia, which delusional disorder does not

— Duration >1 day but <1 month, with full return to premorbid function

— Often follows marked stressor or postpartum

— Differentiator: delusional disorder requires ≥1 month duration

— Uninterrupted period with a major mood episode and active-phase symptoms of schizophrenia, plus ≥2 weeks of delusions/hallucinations without prominent mood symptoms

— Mood symptoms present for majority of total illness duration

— Differentiator: delusional disorder mood episodes are brief relative to delusional periods

— Psychosis occurs exclusively during mood episodes

— Delusions often mood-congruent (guilt/worthlessness in MDD; grandiosity in mania)

— Treatment: antidepressant + antipsychotic, or mood stabilizer + antipsychotic, or ECT

— Differentiator: in delusional disorder, delusions persist independent of mood

— Temporal relationship to intoxication, withdrawal, or medication exposure

— Resolves within ~1 month of cessation (some persist longer, e.g., methamphetamine)

— Differentiator: by DSM criteria, delusional disorder is excluded if substance-induced

Schizophrenia:

Schizophreniform disorder:

Brief psychotic disorder:

Schizoaffective disorder:

Major depressive or bipolar disorder with psychotic features:

Substance/medication-induced psychotic disorder:

Board pearl: A vignette saying "the patient also hears voices commenting on his actions" → this is not delusional disorder; reclassify toward schizophrenia spectrum. Tactile (parasitosis) and olfactory hallucinations related to the delusional theme are permitted.

Key distinction: The cleanest fork is functioning + no hallucinations/disorganization (delusional disorder) versus functional decline + Criterion A symptoms (schizophrenia spectrum).

Key Differentials — Medical, Neurologic, and Other Causes

— Alzheimer, Lewy body, frontotemporal, vascular

— Lewy body: visual hallucinations, parkinsonism, fluctuating cognition, REM behavior disorder, antipsychotic sensitivity

— FTD-behavioral variant: disinhibition, apathy, executive dysfunction, sometimes paranoid delusions

— Differentiator: cognitive decline precedes or accompanies delusions

— Acute onset, fluctuating course, inattention, altered consciousness

— Look for infection (UTI, pneumonia), metabolic derangement, polypharmacy, withdrawal

— Differentiator: clouded sensorium — never present in delusional disorder

— Temporal lobe epilepsy: stereotyped episodes, auras, postictal confusion

— Stroke: focal deficits, especially right hemisphere (Capgras, Fregoli)

— Brain tumors: frontal/temporal mass with personality change and delusions

— Multiple sclerosis, Huntington, Parkinson, Wilson disease

— Neurosyphilis and HIV-associated neurocognitive disorder

— Autoimmune encephalitis (anti-NMDA-R): young, subacute psychiatric symptoms, dyskinesias, autonomic instability, seizures

— Thyrotoxicosis, hypothyroidism (myxedema madness)

— Cushing syndrome, Addison disease

— Hypercalcemia, hyponatremia

— B12 deficiency, pellagra (niacin), thiamine deficiency

— Steroids (dose-related, often >40 mg prednisone equivalent)

— Dopaminergic agents (levodopa, pramipexole)

— Anticholinergics in elderly

— Stimulants, atomoxetine

— Interferon, isotretinoin, varenicline, mefloquine

— Paranoid PD: lifelong pattern of mistrust without fixed delusions; reality testing intact under pressure

— Schizotypal PD: odd beliefs, magical thinking, but no frank delusions

— Differentiator: delusional disorder has discrete fixed beliefs that meet "delusion" threshold

— Repetitive thoughts/behaviors with at least some intermittent insight

— BDD: preoccupation with imagined defect — overlap with somatic type DD; if insight is absent, BDD with "absent insight/delusional beliefs" specifier preferred over delusional disorder

Major and mild neurocognitive disorders (dementia):

Delirium:

Neurologic causes:

Endocrine and metabolic:

Medication-induced:

Personality disorders:

OCD with poor insight / body dysmorphic disorder:

Board pearl: A 30-year-old with new psychosis, orofacial dyskinesias, autonomic instability, and ovarian teratoma on imaging → anti-NMDA receptor encephalitis — order CSF antibodies, treat with steroids/IVIG/rituximab and tumor removal, not just risperidone.

Long-Term Plan, Maintenance Therapy, and Relapse Prevention

— After first remission, continue antipsychotic for at least 1–2 years at the effective dose

— Many patients require indefinite treatment given chronic course and relapse on discontinuation

— Do not abruptly stop — taper slowly over months if discontinuation is attempted, and only with stable function and shared decision-making

— Aim for the lowest effective dose that prevents relapse

— Consider LAI conversion for any patient with adherence concerns, prior relapse off medication, or limited insight — which describes most delusional disorder patients

— CBT for psychosis (CBTp): targets distress, conviction, and behavioral consequences without confronting belief truth

— Supportive therapy: continuity, problem-solving, monitoring

— Family-focused therapy / psychoeducation: reduces expressed emotion and relapse

— Motivational interviewing for comorbid substance use, especially in jealous type

— Depression: SSRI (sertraline, escitalopram preferred); avoid bupropion alone in psychotic illness

— Anxiety: SSRI; short-term benzodiazepine only if needed

— Alcohol use disorder: naltrexone or acamprosate, AA referral

— Tobacco: varenicline can rarely worsen psychiatric symptoms — monitor; bupropion or NRT alternatives

— Annual fasting lipids, HbA1c, weight, waist circumference, BP

— Lifestyle: Mediterranean-style diet, ≥150 min/week moderate activity, smoking cessation

— Statin per ASCVD risk; lower threshold given iatrogenic dyslipidemia

— Treat hypertension to standard targets; metformin if SGA-induced weight gain or prediabetes

Treatment duration:

Maintenance dosing:

Psychotherapy integration:

Comorbidity management:

Metabolic and cardiovascular health (long-term):

Bone health: if hyperprolactinemia >6 months → check prolactin, consider switching agent (aripiprazole lowers prolactin), DXA if amenorrhea or hypogonadism.

Vaccinations and primary care integration: patients with serious mental illness die ~15 years earlier than the general population, largely from preventable medical illness — ensure flu, COVID, pneumococcal, shingles, colon/breast/cervical cancer screening per USPSTF.

Board pearl: The largest contributor to premature mortality in serious mental illness is cardiovascular disease — Step 3 expects you to address it as aggressively as the psychiatric symptoms.

Step 3 management: Build a written longitudinal care plan with PCP, psychiatry, therapy, labs schedule, and emergency contacts; share via the patient portal.

Follow-Up, Monitoring, and Counseling Cadence

— Week 1–2: side effect check, adherence, symptom trajectory

— Weeks 4 and 6: dose adequacy, response assessment

— Weeks 8–12: metabolic recheck (weight, BP, fasting glucose/lipids)

— Monthly for first 6 months, then every 1–3 months once stable

— More frequent during medication changes, life stressors, or relapse warning signs

— Symptomatic: conviction in delusion (rate 0–10), associated distress, behavioral consequences (lawsuits, confrontations, isolation), function (work, relationships, ADLs)

— Safety: suicidal ideation (PHQ-9 item 9), violence risk, IPV in jealous type

— Medication: adherence (pill counts, pharmacy refills, family report, LAI receipt), side effects (EPS via simple bedside exam, AIMS q6mo)

— Metabolic: weight/BMI each visit, BP each visit, fasting lipids and HbA1c at 3 months then annually

— ECG: baseline; repeat with dose changes or new QT-prolonging meds

— Prolactin: only if symptomatic

— Clozapine: ANC per REMS schedule; troponin/CRP weekly × 4 weeks then PRN

— Sleep disruption

— Increased preoccupation with delusional content

— Social withdrawal beyond baseline

— Reduced self-care

— New legal/financial actions tied to belief

— Substance use uptick

— Adherence framing (focus on function and distress reduction, not "belief change")

— Side effect anticipation and proactive management

— Driving safety: caution if sedating regimen, particularly elderly

— Pregnancy planning for women of reproductive age

— Heat illness risk in hot weather (impaired thermoregulation on antipsychotics)

— Smoking interaction with olanzapine/clozapine — if patient quits, levels rise; if resumes, levels fall

— PCP for cardiometabolic and preventive care

— Therapist for CBTp/supportive

— Pharmacist for interactions

— Social work for housing/benefits

Visit schedule (outpatient, post-diagnosis):

Monitoring parameters by domain:

Relapse warning signs to teach patient and family:

Counseling priorities:

Care coordination:

Board pearl: A patient stable on clozapine stops smoking during a hospitalization and develops sedation, hypotension, and sialorrhea → clozapine levels have risen; consider dose reduction and obtain a level.

Step 3 management: Document a written relapse prevention plan with at least three early warning signs and the contact pathway, signed by patient and a designated family member.

Ethical, Legal, and Patient Safety Considerations

— Capacity is decision-specific and time-specific, not global

— Four elements: understand the information, appreciate the situation and consequences, reason through options, express a choice

— A patient with delusional disorder may retain capacity for many decisions (e.g., consenting to colonoscopy) while lacking capacity for the one decision contaminated by the delusion (refusing treatment because the doctor is "the persecutor")

— Document the assessment explicitly

— Before starting antipsychotic, disclose tardive dyskinesia risk (irreversible in some), metabolic effects, sexual dysfunction, sedation, and (in elderly with dementia) black-box mortality warning

— In somatic type, patients may refuse antipsychotic because they believe their problem is parasitic — frame the medication as treating distress and itch sensation; do not deceive

— Identifiable victim + credible threat = obligation to act (warn victim, notify law enforcement, hospitalize, or intensify treatment)

— Especially relevant in jealous and persecutory subtypes

— Document the threat verbatim, the risk assessment, and actions taken

— Intimate partner violence: in many states not mandatory, but document, offer resources, and assess safety; child or elder abuse witnessed in the home is mandatory

— Firearm access in patients with violence or suicide risk: counsel on safe storage / voluntary surrender; some states have extreme risk protection orders (ERPOs / red flag laws)

— Criteria: danger to self, others, or grave disability due to mental illness

— Use least restrictive alternative; outpatient commitment exists in many states (e.g., Kendra's Law in NY, Laura's Law in CA)

— Court-ordered medication requires separate adjudication in most states

— Cannot disclose without consent except for safety

— Can receive information from family even without patient consent — useful for collateral

— Discharge from ED or inpatient to outpatient is the highest-risk window for non-adherence and relapse

— Arrange follow-up within 7 days, provide bridge prescription, send records to outpatient provider, give crisis line, confirm a responsible adult is involved

Capacity assessment:

Informed consent edge case:

Duty to protect / Tarasoff:

Mandatory reporting:

Involuntary treatment and commitment:

Confidentiality vs. family involvement:

Transition-of-care risk (Step 3 favorite):

Board pearl: A patient with somatic delusional parasitosis refuses risperidone. You have not lost capacity grounds — the refusal is consistent with their (delusional) belief but the decision-making is structurally intact. Continue alliance-building, do not override autonomy absent danger.

High-Yield Associations and Rapid-Fire Clinical Facts

— Erotomanic → "celebrity is secretly in love with me" → female patients, stalking, restraining orders

— Grandiose → "I have invented the cure for cancer" without mania

— Jealous (Othello) → middle-aged male, alcohol, partner violence

— Persecutory → "neighbors are spying through vents" → most common type

— Somatic (Ekbom) → "bugs under my skin," matchbox sign, dermatology hopping

— Capgras: familiar person replaced by an impostor — right hemisphere lesions, Lewy body dementia

— Fregoli: strangers are actually one familiar person in disguise

— Cotard: nihilistic delusion (I am dead / my organs are missing) — severe MDD with psychotic features

— De Clérambault: erotomania

— Folie à deux: shared delusion with close contact

— Pimozide classically associated with delusional parasitosis — QT prolongation, EPS

— Pimavanserin: 5-HT2A inverse agonist, FDA-approved for Parkinson disease psychosis — no D2 blockade, no worsening of motor symptoms

— Clozapine: ANC monitoring (REMS), agranulocytosis, myocarditis, seizures, sialorrhea, ileus, weight gain

— Risperidone: highest prolactin elevation among SGAs

— Olanzapine: highest metabolic burden

— Aripiprazole: partial D2 agonist, akathisia, weight-neutral-ish

— Ziprasidone, iloperidone, pimozide, haloperidol IV: QT prolongation

— Smoking induces CYP1A2 → ↓ olanzapine and clozapine levels

Subtype mnemonics and signature vignettes:

Classical eponyms:

Pharmacology pearls:

Workup must-haves in any new psychosis stem: TSH, B12, RPR/HIV, urine tox, MRI brain, ECG.

Epidemiology numbers: prevalence ~0.2%; persecutory most common; onset typically 40s–60s.

Duty to protect: identifiable victim + credible threat → warn, hospitalize, notify police; document.

Postpartum psychosis ≠ delusional disorder; it is an emergency linked to bipolar disorder.

Prognosis better with: acute onset, identifiable precipitant, female sex, younger age, persecutory/somatic types.

Anti-NMDA-R encephalitis: young woman, subacute psychosis + dyskinesias + autonomic instability + seizures + ovarian teratoma — treat the encephalitis, not just the delusion.

Board pearl: When the vignette describes preserved function + non-bizarre fixed belief + middle age + no hallucinations → answer is delusional disorder; next step is usually risperidone plus CBT.

Board Question Stem Patterns

— Stem: "A 55-year-old man insists his wife is having an affair despite no evidence; he checks her phone nightly and follows her car. He drinks 8 beers daily. Exam unremarkable, MMSE 30/30."

— Answer: Jealous type delusional disorder + screen for IPV, treat alcohol, antipsychotic.

— Stem includes "auditory hallucinations commenting on her actions" or "marked decline in self-care" → schizophrenia, not delusional disorder.

— Stem with preserved hygiene, employment, and one fixed non-bizarre belief → delusional disorder.

— 65-year-old new persecutory delusions, ataxia, macrocytic anemia → B12 deficiency, next step is B12 level.

— 30-year-old female, psychosis + orofacial dyskinesia + ovarian mass → anti-NMDA encephalitis, LP for antibodies.

— Patient on prednisone 60 mg/day → steroid-induced psychosis, taper steroids if possible.

— Delusional parasitosis → risperidone or olanzapine (or pimozide classically).

— Parkinson disease with psychosis → pimavanserin or low-dose quetiapine/clozapine; avoid haloperidol.

— Pregnant patient → continue haloperidol or olanzapine/quetiapine, monitor neonate.

— Patient says "I'm going to kill my landlord, and I have a gun" → hospitalize and notify intended victim and law enforcement, even over patient objection.

— Wife of patient develops same delusion → separate, treat the primary; secondary often resolves spontaneously.

— New mother, day 14 postpartum, rapid-onset delusion her baby is the devil → postpartum psychosis, admit, consider ECT, antipsychotic + mood stabilizer, screen for bipolar.

— 82-year-old with cognitive decline and accusations of theft against caregivers → major neurocognitive disorder with behavioral disturbance; first-line is non-pharmacologic (environment, hearing aids, routine); antipsychotic only if dangerous behavior, with black-box discussion.

— Somatic patient refuses dermatology biopsy because "the bugs will spread" → assess capacity for that specific decision; may still have capacity to refuse non-emergent care.

Pattern 1 — Subtype identification:

Pattern 2 — Differential anchor (delusional disorder vs schizophrenia):

Pattern 3 — Secondary cause workup:

Pattern 4 — Pharmacology selection:

Pattern 5 — Tarasoff / duty to protect:

Pattern 6 — Folie à deux:

Pattern 7 — Postpartum vs delusional disorder:

Pattern 8 — Elderly with dementia and paranoia:

Pattern 9 — Capacity question:

Board pearl: The most common wrong answers on Step 3 are confronting the delusion directly and discharging a patient with active homicidal ideation — neither is ever correct.

One-Line Recap

Delusional disorder is a chronic psychotic illness defined by ≥1 month of one or more non-bizarre fixed delusions with preserved functioning and without prominent hallucinations or disorganization, managed primarily with a second-generation antipsychotic, CBT for psychosis, and aggressive secondary-cause exclusion — while addressing safety, capacity, and comorbidity.

— Diagnosis: ≥1 delusion for ≥1 month + Criterion A for schizophrenia not met + function not markedly impaired + behavior not bizarre + not better explained by mood, substance, or medical condition. Seven subtypes — erotomanic, grandiose, jealous, persecutory, somatic, mixed, unspecified.

— Workup: TSH, B12, RPR, HIV, urine toxicology, CMP/CBC, MRI brain (especially late onset), ECG before antipsychotic, pregnancy test. Consider anti-NMDA receptor antibodies in young patients with autonomic/movement features.

— Treatment: SGA first-line (risperidone, olanzapine, aripiprazole); pimozide historically tied to delusional parasitosis; pimavanserin for Parkinson psychosis; clozapine for treatment resistance with REMS monitoring; LAIs early when adherence is the failure mode; combine with CBTp and family psychoeducation; avoid confronting or colluding with the belief.

— Safety and systems: assess violence (jealous, persecutory) and suicide at every visit; Tarasoff duty to protect when an identifiable victim is threatened; capacity is decision-specific; black-box warning in elderly dementia patients; arrange 7-day follow-up after any ED or inpatient transition; integrate cardiometabolic monitoring and preventive primary care because cardiovascular disease — not psychosis — is the leading cause of premature death.

High-yield recap bullets:

Final board pearl: When the stem gives you a middle-aged, well-groomed, employed patient with one fixed non-bizarre belief and a normal MSE outside that belief — the diagnosis is delusional disorder, the medication is a second-generation antipsychotic, and the rate-limiting step is the therapeutic alliance that makes adherence possible.