The TIDE-project (Tracking premenstrual Increases in Depressive Episodes) investigates how often depressive symptoms worsen in women in the days or week before their periods, a phenomenon called Premenstrual Exacerbation (PME) of depression. ‘Many women with depression find that their symptoms increase monthly in the week before their periods, which seems to be associated with longer and more severe depressive episodes,’ says Morssinkhof. The research focuses on how common PME is, whether measuring PME is feasible in clinical practice, and whether women with PME are more likely to experience depression around pregnancy. In doing so, the TIDE project hopes to contribute to better recognition, detection, and treatment of PME in depression.