The age of onset of anxiety disorders

_Objective:_ The objective was to estimate the age of onset (AOO) for all anxiety disorders and for specific subtypes. Gender differences in the AOO of anxiety disorders were examined, as were the influence of study characteristics on reported AOOs. _Methods:_ Seven electronic databases were searched up to October 2014, with keywords representing anxiety disorder subtypes, AOO, and study design. The inclusion criteria were studies using a general population sample that provided data on the AOO for all anxiety disorders, or specific anxiety disorders, according to DSM-III-R, DSM-IV, or ICD-10 criteria. _Results:_ There were 1028 titles examined, which yielded 24 studies meeting the inclusion criteria. Eight studies reported the AOO and gender. Meta-analysis found a mean AOO of all anxiety disorders of 21.3 years (95% CI 17.46 to 25.07). Separation anxiety disorder, specific phobia, and social phobia had their mean onset before the age of 15 years, whereas the AOO of agoraphobia, obsessive-compulsive disorder, posttraumatic stress disorder, panic disorder, and generalized anxiety disorder began, on average, between 21.1 and 34.9 years. Meta-analysis revealed no difference in the AOO between genders. A prospective s