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PS7.1 | Anxiety Disorders in Primary Care — SDL Guide

Learning Objectives

• Recognise the clinical presentation of GAD, Panic Disorder, Social Anxiety Disorder, and Specific Phobia
• Distinguish anxiety disorders from medical mimics such as hyperthyroidism and cardiac arrhythmia
• Apply DSM-5 diagnostic criteria for the common anxiety disorders, citing duration thresholds with their classification system
• Formulate an evidence-based management plan: SSRIs as first-line pharmacotherapy and CBT as psychological treatment
• Identify the appropriate use and limitations of benzodiazepines, and explain the dependence risk to patients
• Determine when a patient with anxiety disorder requires referral to secondary psychiatric services

INSTRUCTIONS

Anxiety disorders are the most prevalent mental health conditions in primary care worldwide, yet they are frequently unrecognised and undertreated. Missed diagnosis leads to unnecessary medical investigations, patient distress, and avoidable morbidity. As a Year-3 student soon entering internship, you will encounter anxious patients in every clinical posting — as the general practitioner in a community health centre, you need to diagnose and initiate treatment without delay. This module provides the skills to do so confidently and safely.

References

• Ahuja N. A Short Textbook of Psychiatry, 8th ed. Jaypee Brothers, 2022. Ch. 7: Anxiety and Related Disorders (textbook)
• Kaplan & Sadock's Synopsis of Psychiatry, 12th ed. Wolters Kluwer, 2022. Ch. 13: Anxiety Disorders (textbook)

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Version 2.0 | NMC CBME 2024

Recognising Anxiety Disorders: Clinical Presentation

Anxiety disorders share a common substrate — excessive, disabling fear or worry — but differ in their trigger, pattern, and duration. The primary care physician's task is to identify the predominant symptom cluster and map it to the correct diagnosis. This determines both the treatment choice and the prognosis.

Generalised Anxiety Disorder (GAD) presents as pervasive, free-floating worry about multiple everyday domains (finances, health, family, work), present on more days than not. The patient typically cannot control the worry and experiences associated features: restlessness, easy fatigability, difficulty concentrating, irritability, muscle tension, and disturbed sleep. It is the 'always-on' form of anxiety — unlike panic disorder, there are no discrete sudden attacks. GAD is the most common anxiety disorder seen in primary care and is frequently comorbid with depression.

Panic Disorder presents with recurrent, unexpected panic attacks — discrete surges of intense fear that peak within minutes and include ≥4 of 13 DSM-5 somatic and cognitive symptoms: palpitations, sweating, trembling, shortness of breath, choking sensation, chest pain, nausea, dizziness, chills or hot flushes, paraesthesiae, derealisation/depersonalisation, fear of losing control, and fear of dying. Crucially, the attacks are 'unexpected' — they arise without an obvious trigger. After one or more attacks, the patient develops ≥1 month of anticipatory worry about future attacks or maladaptive behavioural change (agoraphobia — avoidance of situations where escape might be difficult).

Social Anxiety Disorder (Social Phobia) centres on intense fear of scrutiny or negative evaluation in social or performance situations — public speaking, meeting strangers, eating in public, using a telephone. Patients fear that they will embarrass or humiliate themselves, or that others will notice their anxiety. They avoid these situations or endure them with marked distress. This is distinct from ordinary shyness in its severity and functional impairment.

Specific Phobia involves intense, disproportionate fear of a circumscribed object or situation: needles, blood, heights, animals, flying, closed spaces. The patient recognises the fear as excessive but cannot control it. Exposure triggers immediate anxiety, often meeting criteria for a panic attack. The patient structures their life around avoidance.

Disorder	Core feature	Trigger pattern	Duration criterion (DSM-5)
GAD	Pervasive worry, multiple domains	Continuous, non-specific	≥6 months
Panic Disorder	Discrete panic attacks	Unexpected, any time	≥1 month post-attack concern
Social Anxiety	Fear of scrutiny/embarrassment	Social/performance contexts	≥6 months
Specific Phobia	Fear of specific object/situation	On exposure	≥6 months

Psychopathology and Aetiology of Anxiety Disorders

Anxiety disorders arise from a complex interplay of neurobiological vulnerability, learned fear responses, and psychosocial stressors. Understanding these mechanisms both deepens clinical insight and directly informs the rationale for specific treatments.

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The neurobiological model centres on the amygdala — the brain's threat-detection nucleus. In anxiety disorders, the amygdala is hyperresponsive: it triggers the hypothalamic-pituitary-adrenal (HPA) axis (releasing cortisol) and activates the sympathetic nervous system (releasing adrenaline and noradrenaline) in response to stimuli that objectively pose little or no threat. Three neurotransmitter systems are critically involved. GABA (gamma-aminobutyric acid), the principal inhibitory neurotransmitter, normally damps amygdala firing; reduced GABAergic activity leads to sustained fear responses — this is the pharmacological target of benzodiazepines. Serotonin (5-HT) modulates emotional tone through prefrontal cortical pathways; serotonin dysregulation accounts for both the mood and the anxiety components of GAD, and is the principal target of SSRIs. Noradrenaline, released from the locus coeruleus, mediates the physical arousal symptoms — palpitations, sweating, tremor — that dominate the presentation of panic attacks.

The fear-conditioning model (Pavlovian) explains panic disorder and specific phobias elegantly: an initial panic attack (unconditioned stimulus) becomes paired with a neutral context or internal cue (conditioned stimulus), such that the context alone subsequently triggers panic. This 'interoceptive conditioning' — where normal physiological sensations like a slight increase in heart rate become triggers — explains why attacks feel random to the patient but are actually conditioned responses.

The biopsychosocial risk factors include: genetic predisposition (heritability of GAD and panic disorder is 30–40%); temperament (behavioural inhibition in childhood — excessive shyness and fearfulness — strongly predicts adult anxiety disorders); adverse childhood experiences (abuse, neglect, parental loss); chronic life stress; and personality traits such as neuroticism and harm avoidance. Protective factors include secure attachment, social support, and high resilience.

Important: anxiety disorders rarely occur in isolation. GAD has a lifetime comorbidity with major depression exceeding 60%. Panic disorder commonly co-occurs with agoraphobia. Alcohol misuse may develop as a maladaptive coping mechanism, and its withdrawal exacerbates anxiety — creating a vicious cycle the primary care physician must identify and address.

Diagnosis and Distinguishing Anxiety from Medical Mimics

The single most important diagnostic discipline in primary care psychiatry is exclusion of medical causes before labelling anxiety as 'primary.' Several medical conditions produce symptoms virtually identical to anxiety disorders, and missing them causes serious harm to the patient — both by delaying appropriate medical treatment and by exposing them to unnecessary psychiatric stigma and inappropriate psychotropic medication. In clinical practice, the experienced primary care physician approaches every new anxiety presentation with two simultaneous tasks running in parallel: gathering the psychiatric symptom profile while simultaneously scanning for biological red flags that demand investigation first. The three commonest medical mimics — hyperthyroidism, cardiac arrhythmia, and phaeochromocytoma — each have distinguishing clinical features and targeted investigations. Hypoglycaemia is an additional mimic specific to diabetic patients on insulin or sulfonylureas. The mandatory baseline investigations for every new anxiety presentation are TSH, fasting blood glucose, and ECG; further investigations are ordered based on specific clinical indications.

Key medical mimics and their distinguishing investigations:
- Hyperthyroidism: palpitations, sweating, anxiety, tremor, weight loss, heat intolerance, diarrhoea; distinguish by TSH (suppressed in hyperthyroidism), free T4 (elevated). The patient may have a goitre. Unlike GAD, the worry content is not the predominant feature — the somatic symptoms dominate.
- Cardiac arrhythmia (supraventricular tachycardia, paroxysmal atrial fibrillation): episodic palpitations that may be indistinguishable from panic by symptoms alone. A 12-lead ECG during an episode, or a 24-hour Holter monitor, is required if the history suggests arrhythmia (abrupt onset, regular fast pulse, terminated by vagal manoeuvres).
- Phaeochromocytoma: episodic hypertension, headache, sweating, pallor, and palpitations — the classic 'surgical' mimic of panic disorder. Investigate with urine catecholamines/metanephrines when episodic hypertension accompanies the anxiety symptoms.
- Hypoglycaemia: in diabetic patients on insulin or sulfonylureas, hypoglycaemia causes sweating, tremor, palpitations, and anxiety. Check capillary blood glucose during symptoms.

DSM-5 diagnostic criteria (attribute system):
For GAD (DSM-5): excessive anxiety and worry about multiple events or activities, present on more days than not for ≥6 months (DSM-5 criterion; note that ICD-11 uses 'several months' without specifying a fixed six-month floor), which the patient finds difficult to control, with ≥3 associated symptoms (of 6: restlessness, fatigue, concentration difficulty, irritability, muscle tension, sleep disturbance). Causes clinically significant distress or functional impairment, not attributable to a substance or medical condition.

For Panic Disorder (DSM-5): recurrent unexpected panic attacks (≥4 of 13 specified symptoms, peaking within minutes), followed by ≥1 month of persistent concern about further attacks, their implications, or significant behavioural change.

For Social Anxiety Disorder (DSM-5): marked fear or anxiety about ≥1 social situation in which the person is exposed to possible scrutiny; fear out of proportion to actual threat; duration ≥6 months; causes significant distress or impairment.

Mental Status Examination (MSE) features in anxiety:
- Appearance: anxious facies, psychomotor restlessness or fidgeting; may be pale and sweating
- Speech: may be rapid, pressured, or halting
- Affect: anxious, apprehensive, tense
- Thought content: excessive worry (GAD), fear of dying or losing control (panic), fear of embarrassment (social anxiety)
- Perception: no hallucinations or illusions (hallucinations suggest psychosis or substance intoxication)
- Cognition: intact; concentration may be impaired due to worry
- Insight: usually preserved — patients recognise their fear is excessive, which distinguishes anxiety from delusional disorder

Mandatory baseline investigations in all new presentations: TSH, fasting blood glucose, ECG, FBC (anaemia can worsen anxiety). Reserve further investigations (echocardiogram, Holter, urine catecholamines) for specific clinical indications.