Age of onset of mental disorders: etiopathogenetic and treatment implications.

Age of onset (AOO) of anxiety disorders could serve as a vital statistic in the formulation of mental health policy. Previous reviews have reported on the AOO of anxiety disorders in the general population. However, these review studies did not systematically estimate the AOO of different anxiety disorder subtypes, and did not examine factors that might have influenced reported AOO.

The aims of the present study were (1) to estimate the AOO for all anxiety disorders and for specific subtypes, (2) to examine gender differences in AOO of anxiety disorders, and (3) to examine the influence of study characteristics on reported AOO.

Seven electronic databases were searched with keywords representing anxiety disorder subtypes, AOO and study design. The inclusion criteria were studies using a general population sample that provided data on AOO for all anxiety disorders, or specific anxiety disorders, according to DSM-III-R, DSM-IV or ICD-10 criteria. Meta-analysis was used to estimate AOO and gender differences, while meta-regression was used to examine the influence of study characteristics.

A total of 1028 titles were examined, which yielded 24 studies meeting the inclusion criteria. Meta-analysis found an average 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 AOO of agoraphobia, obsessive compulsive disorder, post-traumatic stress disorder, panic disorder and generalized anxiety disorder began on average between 21.1 and 34.9 years. Anxiety disorder is more common in women, but meta-analysis revealed no difference in AOO between genders. Prospective study design and higher developmental level of the study country were associated with earlier AOO.

Results from this meta-analysis indicate that anxiety disorder subtypes differ in mean AOO, with onsets ranging from early adolescence to young adulthood. These findings suggest that prevention strategies of anxiety disorders should be directed towards the factors associated with the development of subtypes of anxiety disorder in the age groups with the greatest vulnerability for developing those disorders.

The authors have not supplied their declaration of competing interest.