TABLE I. Evolution of the definition of generalized anxiety disorder in succeeding editions of the DSM and ICD. DSM, Diagnostic and Statisticai Manual of Mental Disorders; GAD, generalized anxiety disorder; iCD, internationai Statistical Classification of Diseases and Related Health Problems; OCD, obsessive-compulsive disorder. Modified and updated from reference 1 9: Rickels K, Rynn M. Overview and clinical presentation of generalized anxiety disorder. Psychiatr Clin North Am. 2001;24(1):1-17.

	DSM-III (1980)	DSM-III-R (1987)	DSM-IV (1994)	DSM-5 (2013)	ICD-10 (1992)	ICD-11 Beta Draft
Anxiety	Generalized, persistent anxiety.	Unrealistic/ excessive anxiety and worry (apprehensive expectation) about 2 or more life circumstances.	- Excessive anxiety and worry (apprehensive expectation) about a number of events or activities. - Difficult to control the worry.	- Excessive anxiety and worry (apprehensive expectation) about a number of events or activities. - Difficult to control the worry.	Generalized and persistent anxiety, not restricted to or even predominating in any environmental circumstances (ie, “free-floating”).	Marked symptoms of anxiety accompanied by either general apprehension (ie, “free-floating anxiety”) or worry focused on multiple everyday events (family, health, finances, school, or work).
Duration	≥ 1 month	≥ 6 months	More days than not for at least 6 months.	More days than not for at least 6 months.	Most days for at least several weeks at a time, and usualiy for several months.	More days than not for at least several months.
Number of symptoms	Unspecified number of symptoms from 3 of 4 categories.	At least 6 of 18 specified symptoms.	At least 3 of 6 specified symptoms.	At least 3 of 6 specified symptoms.	Unspecified number of symptoms.	Unspecified number of symptoms.
Symptoms or symptom categories	1. Motor tension. 2. Autonomic hyperactivity. 3. Apprehensive expectation. 4. Vigilance and scanning.	- Motor tension (n = 4). - Autonomic hyperactivity (n = 13). - Vigilance and scanning (n = 5)	1. Restlessness or feeling keyed up or on edge. 2. Being easily fatigued. 3. Difficulty concentrating or mind going blank. 4. Irritability. 5. Muscle tension. 6. Sleep disturbance.	Identical to DSM-IV.	- Apprehension (worries about future misfortunes, feeling “on edge”, difficulty in concentrating). - Motor tension. - Autonomic overactivity	Additional symptom such as muscular tension or motor restlessness, sympathetic autonomic overactivity, subjective experience of nervousness, difficulty maintaining concentration, irritability, or sleep disturbance.
Associated features	Mild depressive symptoms.	Mild depressive symptoms.	- Somatic symptoms, exaggerated startle response. - Frequent co-occurrence with mood disorders, other anxiety disorders, substance-related disorders, other conditions associated with stress.	Similar to DSM-IV. Symptoms of autonomic arousal are less prominent in GAD than in other anxiety disorders, such as panic disorder.	/	/
Impairment in social and occupational functioning	Rarety more than mild.	Rarely more than mild.	Significant distress and ïmpairment.	Significant distress and impairment.	/	Significant distress or significant impairment in functioning.
Exclusions	Not due to anotber mental disorder, such as a Depressive Disorder or Schizophrenia.	Not due to an organic factor (hyperthyroidism, caffeine). Anxiety/worry unrelated to panic disorder, social phobia, OCD, or anorexia nervosa.	Not due to a substance, a general medical condition. Does not occur exclusively during a mood disorder, a psychotic disorder, or a pervasive developmental disorder.	Anxiety or worry not better explained by another mental disorder (eg, panic disorder, social anxiety disorder, OCD, separation anxiety disorder, posttraumatic stress disorder, anorexia nervosa, somatic symptom disorder, body dysmorphic disorder, illness anxiety disorder, schizophrenia, or delusional disorder).	The transient appearance of symptoms of depression does not rule out GAD as a main diagnosis. The sufferer must not meet the criteria for depressive episode, phobic anxiety disorder, panic disorder, or OCD.	/
Prevalence	Equally common in males and in females. Rare in the general population.	Not commonly diagnosed in clinical samples, where it is equally common in males and in females.	Sex ratio: two-thirds female in epidemiological studies. Lifetime prevalence: 5% in community sarnple	The lifetime morbid risk is 9%. Females are twice as likely as males to experience GAD. Individuals of European descent tend to experience GAD more frequently than do individuals of non-European descent.	- More common in women. - Often related to chronic environmental stress.