Definition and Overview
Generalized anxiety disorder (GAD) is characterized by excessive and persistent worry about various aspects of daily life for at least 6 months, accompanied by physical symptoms such as muscle tension, restlessness, sleep disturbance, and fatigue [1].
The lifetime prevalence of GAD is approximately 3-6%, with a 12-month prevalence of about 2-3%. It is approximately twice as common in women as in men [1]. Unlike panic disorder's acute episodes, GAD involves chronic, low-grade anxiety that pervades daily life.
Causes and Pathophysiology
Neurobiological Mechanisms
The amygdala-prefrontal cortex circuit dysregulation is a key finding. The amygdala is hyperactive to threat stimuli while prefrontal cortex regulation is impaired [2]. GABAergic and serotonergic system dysfunction are implicated, with reduced GABA receptor binding observed in neuroimaging studies.
Autonomic Dysfunction
GAD patients consistently show reduced heart rate variability (HRV), indicating decreased vagal tone and autonomic inflexibility [3]. Chronic sympathetic hyperactivation manifests as muscle tension, increased startle response, and sleep onset insomnia.
Genetic and Environmental Factors
Heritability is estimated at 30-40%. The serotonin transporter gene (5-HTTLPR), COMT, and MAO-A polymorphisms have been associated with anxiety vulnerability [5]. Childhood adversity, chronic stress, and insecure attachment patterns are environmental risk factors.
Symptoms
The DSM-5 criteria require excessive anxiety and worry about multiple events or activities occurring more days than not for at least 6 months, with difficulty controlling the worry. At least three of the following must be present [1]:
- Restlessness or feeling on edge
- Easy fatigability
- Difficulty concentrating or mind going blank
- Irritability
- Muscle tension
- Sleep disturbance (difficulty falling/staying asleep, restless sleep)
Physical symptoms also include headache, trembling, sweating, nausea, diarrhea, and frequent urination. These autonomic symptoms reflect the chronic sympathetic hyperactivation state.
Diagnosis
GAD is diagnosed clinically using DSM-5 criteria. The GAD-7 scale is a validated screening tool, with scores of 10 or above suggesting moderate-to-severe GAD [1].
Differential diagnosis includes other anxiety disorders (panic disorder, social anxiety), depression, hyperthyroidism, pheochromocytoma, cardiac arrhythmias, and medication/substance effects. Basic blood work including thyroid function tests helps rule out organic causes.
Treatment
Psychotherapy
Cognitive behavioral therapy (CBT) is the first-line psychological treatment. It addresses cognitive distortions (catastrophizing, overestimation of threat) and avoidance behaviors. Meta-analyses show CBT produces clinically significant improvement in 50-60% of GAD patients [3].
Pharmacotherapy
SSRIs (escitalopram, sertraline) and SNRIs (duloxetine, venlafaxine) are first-line medications [4]. Buspirone, a 5-HT1A partial agonist, is an alternative without dependence risk. Benzodiazepines provide rapid relief but should be limited to short-term use due to dependence potential. Pregabalin is approved in some countries for GAD.
Autonomic Neuromodulation
HRV biofeedback training can improve autonomic flexibility. Vagus nerve stimulation (VNS) is being studied for treatment-resistant anxiety. Mindfulness-based stress reduction (MBSR) shows comparable efficacy to CBT in some trials.
Lifestyle Management
- Regular aerobic exercise (30 minutes, 5 times/week) reduces anxiety symptoms
- Sleep hygiene: consistent sleep schedule, limited screen time before bed
- Caffeine and alcohol reduction
- Relaxation techniques: progressive muscle relaxation, diaphragmatic breathing
- Social support and structured daily routines