There have been limited prospective investigations of early clinical markers involved in mood regulation and diagnosis change in young patients. This study aimed to evaluate the changes in impulsivity and defence mechanisms in patients with major depressive disorder (MDD) and bipolar disorder (BD) with acute symptoms and remission compared to healthy controls (HC), and possible psychological predictors of diagnosis conversion. To read the full article, choose Open Athens “Institutional Login” and search for “Midlands Partnership”.