Anxiety Disorders

Anxiety disorders are the most common class of mental disorders, characterized by excessive fear, anxiety, and related behavioral disturbances. While fear is an adaptive response to real or perceived threat, anxiety disorders involve disproportionate reactions that significantly impair functioning.

Distinguishing Normal Anxiety from Disorder

Domain	Normal Anxiety	Anxiety Disorder
Intensity	Proportionate to threat	Disproportionate to the situation
Duration	Time-limited; resolves when threat passes	Persistent; lasts months to years
Function	Adaptive (enhances performance, alertness)	Maladaptive (impairs functioning)
Control	Manageable with coping strategies	Difficult to control despite insight
Distress	Mild to moderate	Significant, often severe
Impairment	Minimal	Substantial (social, occupational)

Generalized Anxiety Disorder (GAD)

GAD is characterized by persistent, excessive, and uncontrollable worry about multiple domains (work, health, finances, relationships) occurring more days than not for at least six months.

Epidemiology

Metric	Value
Lifetime prevalence	~5-10%
12-month prevalence	~2-5%
Female:male ratio	2:1
Mean age of onset	~30 years (but wide range)
Course	Chronic, fluctuating; onset often gradual
Comorbidity	50-90% have at least one comorbid disorder (most commonly MDD, other anxiety disorders)

DSM-5 Diagnostic Criteria

Criterion	Description
A. Excessive anxiety and worry	Worry occurring more days than not for at least 6 months, about numerous events or activities
B. Difficulty controlling worry	The individual finds it difficult to control the worry
C. Associated symptoms (3+ in adults)	Restlessness, easily fatigued, difficulty concentrating, irritability, muscle tension, sleep disturbance
D. Significant distress/impairment	Clinically significant distress or impairment in functioning
E. Exclusions	Not attributable to substance use or another medical condition; not better explained by another mental disorder

Symptom Domains in GAD

Domain	Manifestations
Cognitive	Chronic worry, catastrophizing, intolerance of uncertainty, “what-if” thinking
Physiological	Muscle tension, headaches, fatigue, gastrointestinal distress, trembling
Behavioral	Reassurance-seeking, procrastination, avoidance, over-preparation
Emotional	Irritability, edginess, sense of dread

Neurobiology of GAD

• Prefrontal cortex: Reduced top-down regulation of amygdala
• Amygdala: Hyperreactivity to threat cues
• Neurotransmitters: GABA deficiency, serotonin system dysregulation, norepinephrine hyperactivity
• HPA axis: Chronic mild elevation of cortisol
• Genetics: Moderate heritability (~30%)

Panic Disorder

Panic disorder is characterized by recurrent, unexpected panic attacks and persistent concern about future attacks or their consequences.

Panic Attack

A panic attack is an abrupt surge of intense fear or intense discomfort that reaches a peak within minutes and includes four or more of the following symptoms:

Symptom	Type	Description
Palpitations	Cardiovascular	Pounding heart, accelerated heart rate
Sweating	Autonomic	Diaphoresis
Trembling	Neuromuscular	Shaking
Shortness of breath	Respiratory	Smothering sensation, dyspnea
Choking sensation	Respiratory	Feeling of choking
Chest pain	Cardiovascular	Chest discomfort or pain
Nausea	Gastrointestinal	Abdominal distress
Dizziness	Vestibular	Lightheadedness, unsteady, faint
Derealization	Perceptual	Feelings of unreality or detachment
Fear of losing control	Cognitive	Fear of going crazy
Fear of dying	Cognitive	Fear of impending doom
Paresthesias	Sensory	Numbness, tingling
Chills/hot flushes	Thermoregulatory	Temperature sensations

Types of panic attacks:

• Unexpected (spontaneous): Not associated with a specific trigger
• Situationally bound (cued): Occur almost invariably immediately on exposure to a trigger
• Situationally predisposed: More likely to occur on exposure to a trigger but not invariably

DSM-5 Diagnostic Criteria for Panic Disorder

Criterion	Description
A. Recurrent unexpected panic attacks	Repeated, unexpected surges of intense fear/discomfort
B. Worry about future attacks	Persistent worry about additional attacks or their consequences
C. Maladaptive behavior change	Significant maladaptive change in behavior (e.g., avoidance)
D. Exclusion	Not attributable to substance use or another medical condition
E. Not better explained	Not better accounted for by another mental disorder

Agoraphobia

Agoraphobia is significant fear or anxiety about two or more of the following situations:

1. Using public transportation
2. Being in open spaces (parking lots, marketplaces)
3. Being in enclosed places (shops, theaters)
4. Standing in line or being in a crowd
5. Being outside of the home alone

Key features:

• Fear of these situations because escape might be difficult or help unavailable if panic-like symptoms develop
• Situations actively avoided, require a companion, or endured with intense fear
• Fear is out of proportion to actual danger

Relationship between panic disorder and agoraphobia:

• Many individuals with panic disorder develop agoraphobia
• Agoraphobia can occur without panic disorder (DSM-5 separates the diagnoses)
• Agoraphobia without panic disorder accounts for ~30-50% of agoraphobia cases

Social Anxiety Disorder (Social Phobia)

Social anxiety disorder is characterized by significant fear or anxiety about one or more social situations where the individual may be scrutinized by others.

DSM-5 Criteria

Criterion	Description
A. Fear of social situations	Marked fear/anxiety about social situations involving possible scrutiny (interactions, being observed, performing)
B. Fear of negative evaluation	Fear of acting in a way that will be negatively evaluated or showing anxiety symptoms
C. Anxiety nearly always provoked	Social situations almost always provoke fear or anxiety
D. Avoidance or endurance	Social situations are avoided or endured with intense fear/anxiety
E. Disproportionate	Fear/anxiety is out of proportion to actual threat
F. Duration	Persistent, typically 6 months or more
G. Impairment	Clinically significant distress or impairment
H. Exclusions	Not attributable to substance use or another medical condition

Specifier: Performance only: Fear is restricted to speaking or performing in public.

Epidemiology

Metric	Value
Lifetime prevalence	~7-13%
12-month prevalence	~5-8%
Female:male ratio	1.5:1
Mean age of onset	~13 years (early adolescence)
Course	Usually chronic if untreated

Common Feared Situations

Situation	% Endorsing
Public speaking	~90%
Meeting new people	~70%
Eating/drinking in public	~50%
Using public restrooms	~30%
Writing in front of others	~30%
Returning items to a store	~25%

Specific Phobias

Specific phobia is marked fear or anxiety about a specific object or situation, leading to avoidance or endured with intense distress.

DSM-5 Criteria

Criterion	Description
A. Marked fear	Intense fear/anxiety about a specific object or situation
B. Immediate response	Phobic stimulus almost always provokes immediate fear/anxiety
C. Avoidance/endurance	Active avoidance or endurance with intense fear
D. Disproportionate	Fear is out of proportion to actual danger
E. Duration	Persistent, typically 6 months or more
F. Impairment	Clinically significant distress or impairment

Types of Specific Phobias

Type	Examples	Onset
Animal	Spiders, snakes, dogs, insects	Childhood (usually)
Natural environment	Heights, storms, water	Childhood (variable)
Blood-injection-injury	Needles, blood, medical procedures	Childhood (fainting common)
Situational	Flying, elevators, enclosed spaces, driving	Variable (often mid-20s)
Other	Choking, vomiting, loud sounds, costumed characters	Variable

Blood-injection-injury phobia is unique in that it often produces a vasovagal response (drop in heart rate and blood pressure) leading to fainting, rather than the typical fight-or-flight response.

Pathophysiology of Anxiety Disorders

Neurocircuitry

Brain Region	Role in Anxiety
Amygdala	Threat detection, fear conditioning, emotional arousal
Prefrontal cortex (ventromedial)	Extinction learning, top-down regulation
Anterior cingulate cortex	Conflict monitoring, error processing
Insula	Interoception, body state awareness
Hippocampus	Contextual fear memory
Periaqueductal gray	Defensive responses (freeze, flight, fight)

Neurotransmitters

System	Function in Anxiety
GABA (inhibitory)	Reduced inhibitory tone → increased anxiety
Serotonin	Complex: both anxiogenic and anxiolytic effects via different receptors
Norepinephrine	Increased arousal, autonomic activation
Glutamate (excitatory)	Excessive excitatory signaling in fear circuits
Corticotropin-releasing factor (CRF)	HPA axis activation, stress response

Genetics

Finding	Details
Heritability	~30-50% across anxiety disorders
Shared genetic factors	High genetic correlation across anxiety disorders
Specific loci	Genome-wide association studies identify multiple small-effect variants
Gene-environment interaction	Early adversity increases risk in genetically vulnerable individuals

Learning and Conditioning Models

• Classical conditioning: Neutral stimulus paired with aversive event becomes feared
• Operant conditioning: Avoidance behavior negatively reinforced by reduction in fear
• Observational learning: Fear acquired by observing others’ fearful responses
• Informational transmission: Fear acquired through verbal information
• Failure of extinction: Impaired safety learning contributes to persistence

Evidence-Based Treatment

Pharmacotherapy

Class	Medications	Indications	Key Points
SSRIs	Sertraline, escitalopram, fluoxetine, paroxetine, citalopram	All anxiety disorders (first-line)	Slow onset (2-6 weeks), few side effects, safe in overdose
SNRIs	Venlafaxine, duloxetine	GAD, panic disorder, social anxiety (first-line)	Similar profile to SSRIs; may cause blood pressure elevation
Benzodiazepines	Clonazepam, lorazepam, alprazolam	Short-term use, acute anxiety	Rapid onset, tolerance/dependence risk, avoid as monotherapy
Buspirone	Buspirone	GAD (mild-moderate)	Low abuse potential, no sedation, delayed onset
Beta-blockers	Propranolol	Performance anxiety only	Reduces autonomic symptoms (tremor, tachycardia)
TCAs	Clomipramine, imipramine	Panic disorder, GAD (second-line)	Effective but more side effects than SSRIs
MAOIs	Phenelzine	Social anxiety (treatment-resistant)	Dietary restrictions, hypertensive crisis risk

Cognitive-Behavioral Therapy (CBT)

CBT is the first-line psychological treatment for all anxiety disorders. Core components include:

Cognitive restructuring:

• Identify anxiety-provoking thoughts
• Challenge probability overestimation and catastrophizing
• Develop more realistic, balanced appraisals

Exposure therapy:

• Systematic, repeated confrontation with feared stimuli
• Hierarchy-based (gradual exposure)
• Habituation and extinction learning
• Types: in vivo (real life), imaginal, interoceptive, virtual reality

Key CBT protocols by disorder:

Disorder	Specific Protocol	Key Elements
GAD	CBT for GAD	Cognitive restructuring, worry time, uncertainty tolerance, relaxation
Panic disorder	Panic control treatment (PCT)	Interoceptive exposure, cognitive restructuring of catastrophic misinterpretations
Social anxiety	CBT for social anxiety	Social skills training, attention training, behavioral experiments, videotaped feedback
Specific phobia	One-session treatment	Intensive exposure, participant modeling, cognitive challenge
Agoraphobia	CBT with exposure	Situational exposure hierarchy, panic management skills

Other Psychological Treatments

Modality	Evidence	Application
Acceptance and commitment therapy (ACT)	Moderate to strong	GAD, social anxiety; values-based action, experiential avoidance reduction
Mindfulness-based stress reduction (MBSR)	Moderate	GAD, panic; mindfulness meditation, present-moment awareness
Dialectical behavior therapy (DBT)	Limited for primary anxiety	Anxiety in context of emotion dysregulation, BPD
Psychodynamic therapy	Limited (short-term)	Anxiety related to unconscious conflict
Applied relaxation	Strong	GAD; progressive muscle relaxation, cue-controlled relaxation

Treatment Algorithm

First-line:
  CBT (individually or group)
  OR SSRI/SNRI
  OR Combined CBT + medication

Inadequate response:
  Switch to alternative first-line option
  OR Augment (e.g., CBT if had medication alone; add medication if had CBT alone)

Treatment-resistant:
  Consider alternative medication class (different SSRI/SNRI, TCA, MAOI)
  Augment with atypical antipsychotic or pregabalin (off-label)
  Consider intensive CBT
  Refer to specialist

Maintenance:
  Medication: Continue 6-12 months after remission, then consider taper
  CBT: Booster sessions as needed
  Relapse prevention strategies

Special Populations

Children and Adolescents

• Separation anxiety disorder: Most common childhood anxiety disorder
• School refusal: Common presentation of anxiety
• Parent training: Parents included in treatment
• CBT adapted for developmental level
• SSRIs first-line for moderate-to-severe anxiety

Older Adults

• Anxiety common but often overlooked (attributed to aging or medical illness)
• Higher rates of GAD compared to younger adults
• Caution with benzodiazepines (falls, cognitive impairment)
• SSRIs at lower starting doses due to drug interactions

References

1. American Psychiatric Association. (2022). Diagnostic and Statistical Manual of Mental Disorders (5th ed., text rev.). Arlington, VA: APA.
2. Bandelow, B., et al. (2015). Treatment of anxiety disorders. Dialogues in Clinical Neuroscience, 17(3), 327-335.
3. Craske, M. G., & Stein, M. B. (2016). Anxiety. Lancet, 388(10063), 3048-3059.
4. Hofmann, S. G., et al. (2012). The efficacy of cognitive behavioral therapy: a review of meta-analyses. Cognitive Therapy and Research, 36(5), 427-440.
5. National Institute of Mental Health. (2023). Anxiety Disorders. NIMH.
6. Stein, M. B., & Sareen, J. (2015). Generalized anxiety disorder. New England Journal of Medicine, 373(21), 2059-2068.