Key Facts

Panic disorder involves recurrent unexpected panic attacks and persistent concern about their implications. Panic attacks are sudden surges of intense fear accompanied by physical and cognitive symptoms, peaking within minutes.

Epidemiology

Lifetime prevalence is 2-3%; 12-month prevalence ~1.5%. Women are twice as commonly affected. Age of onset is typically late teens to mid-30s. Panic disorder is frequently comorbid with agoraphobia (~30-50%), depression (~50%), and other anxiety disorders.

Aetiology

• Genetic: Heritability ~40%; first-degree relatives have 4-8× increased risk
• Neurobiological: Amygdala hyperreactivity, locus coeruleus (noradrenergic) overactivity, serotonergic dysfunction
• Cognitive: Catastrophic misinterpretation of bodily sensations (Clark's cognitive model) — e.g., palpitations → "I'm having a heart attack"
• Respiratory: CO2 hypersensitivity theory — panic-prone individuals have lower threshold for CO2-induced anxiety
• Psychosocial: Stressful life events, childhood separation anxiety, parental overprotection

Pathophysiology

• False suffocation alarm theory (Klein): Brainstem CO2 monitor is overly sensitive → triggers alarm response inappropriately
• Sympathetic nervous system activation: Adrenaline surge → tachycardia, sweating, tremor, hyperventilation
• Hyperventilation → respiratory alkalosis → reduced ionised calcium → paraesthesia, dizziness, tetany
• Conditioned fear response: Interoceptive conditioning — benign bodily sensations become associated with panic → anticipatory anxiety → avoidance

Panic Attack Symptoms (≥4 of the following)

• Palpitations or accelerated heart rate
• Sweating
• Trembling or shaking
• Shortness of breath or feeling of smothering
• Chest pain or discomfort
• Nausea or abdominal distress
• Dizziness, light-headedness, or feeling faint
• Chills or hot flushes
• Paraesthesia (numbness or tingling)
• Derealisation or depersonalisation
• Fear of losing control or "going crazy"
• Fear of dying

Associated Features

• Anticipatory anxiety: Persistent worry about when next attack will occur
• Avoidance: Avoiding situations associated with attacks (may develop into agoraphobia)
• Nocturnal panic attacks: Wake from sleep with panic (differentiate from sleep apnoea, cardiac arrhythmia)

Red Flags — Exclude Medical Causes

• Chest pain with cardiac risk factors — ECG, troponin
• Syncope — cardiac arrhythmia assessment
• Weight loss, tremor, heat intolerance — thyrotoxicosis
• Episodes always related to specific trigger — consider phobia rather than panic disorder

Bedside

• GAD-7 and PHQ-9: Screen for comorbid GAD and depression
• Panic Disorder Severity Scale (PDSS): Quantify severity
• Risk assessment: Suicide risk, self-harm, substance misuse

Bloods

• TFTs: Exclude hyperthyroidism
• FBC, glucose: Anaemia, hypoglycaemia
• U&Es, calcium: Electrolyte abnormalities

Special Tests

• ECG: Exclude arrhythmia, QTc prolongation baseline
• Echocardiogram: If cardiac symptoms concerning
• Holter monitor: If palpitations not captured on ECG

Non-pharmacological

• CBT: First-line psychological therapy — Clark's cognitive model
  • Psychoeducation about panic cycle
  • Cognitive restructuring of catastrophic misinterpretations
  • Interoceptive exposure (deliberately inducing feared sensations — e.g., hyperventilation, spinning)
  • Behavioural experiments to test catastrophic predictions
• Guided self-help: Based on CBT principles
• Breathing retraining: Slow diaphragmatic breathing

Pharmacological (NICE CG113)

• First-line: SSRI — sertraline 50mg OD or citalopram 10-20mg OD (start low, increase slowly — SSRIs can initially worsen anxiety)
• Second-line: SNRI — venlafaxine 75-225mg; or imipramine (TCA) if SSRIs/SNRIs not tolerated
• Short-term crisis only: Benzodiazepines (diazepam 2-5mg PRN) — maximum 2-4 weeks
• Not recommended: Beta-blockers (ineffective for panic disorder, unlike performance anxiety)

Referral Criteria

• Failed first-line SSRI + CBT — secondary care
• Severe agoraphobia preventing engagement with treatment
• Significant comorbidity (depression, substance misuse)
• Diagnostic uncertainty

• CBT: 70-90% response rate; gains generally maintained at 2-year follow-up
• SSRIs: 50-60% response rate; ~30% relapse on discontinuation
• Combined CBT + SSRI: Best outcomes in moderate-severe panic disorder
• Natural course: Without treatment, panic disorder tends to be chronic with waxing and waning; spontaneous remission in ~30-40%
• Agoraphobia: Develops in ~30-50% if untreated; significantly worsens prognosis
• Mortality: No increased all-cause mortality, but significant functional impairment and reduced quality of life

Clark's Cognitive Model of Panic

Panic Disorder vs GAD