Evidence based primarily on a small number of either prospective or retrospective case studies that included a small number of participants and often used non-validated outcome measures for a short period of follow-up, suggests that antidepressants, particularly SSRIs, show improvement of aggression and self-injurious behaviour on average in less than 50% of cases and the rest show either no improvement or deterioration. The effect is most pronounced in the presence of an underlying anxiety or an associated diagnosis of obsessive-compulsive disorder. Most studies have highlighted the concern regarding adverse effects.