To the best of our knowledge, no quality assessment measure has been validated for the type of studies included in the current meta-analysis. Therefore, the risk of bias was evaluated with an ad-hoc list of criteria derived from the Newcastle-Ottawa scale (NOS) [33], which included the definition of onset age of the mental disorder, diagnostic criteria employed, and study design. However, since these criteria were not validated, they were not employed to categorise studies according to their quality; they were only used for descriptive reporting.
