Depression is the leading cause of disability worldwide and is a major contributor to the overall global burden of disease, with more than 350 million people of all ages suffering from depression. Especially when recurrent and with moderate or severe intensity, depression may become a serious health condition. Further, we now know that many young people suffer from clinical depression. In fact, major depression is one of the most common mental health disorders in children and adolescents, with an estimated one year prevalence of 4-5% in mid-late adolescence and 5.6% in young people of 13-18 year old. Depression in young people is a precursor of adult depressive disorder which is strongly linked to poor physical health outcomes, lower income and increased unemployment, with half of those with lifelong recurrent depression starting to develop their symptoms before the age of 15 years. Thus, to recognize and treat depression in young ages is crucial. To sum up, depression is a substantial and largely unrecognized problem among young people that warrants an increased need and opportunity for identification and intervention. Understanding how specific factors might prevent and/od be effective in the treatment of depression in young people is crucial for the development of early intervention and treatment of depression among youths.
Depression results from a complex interaction of social, psychological, and biological factors. Recent attempts have been made by the Wellcome Trust to investigate the evidence for different active ingredients (i.e. those aspects of an intervention that drive clinical effect, are conceptually well defined, and link to specific hypothesised mechanisms of action) deemed to help prevent, treat, and manage depression in young people globally, including behaviours and activities, beliefs and knowledge, brain/body functions, cognitive and attentional skills, human connections, and socioeconomic factors. However, what is still unknown is which of these potential active ingredients and/or which combination of these active ingredients constitute a more accurate predictor for different groups of young people with depression, including those with high levels of depression.
A number of important issues need further investigation to aid early intervention in depression. First, most studies in young people with depression have focused on single time points, while very few studies have investigated the different trajectories of depression across adolescence and young adulthood, including young people with persistent high levels of depression. In addition, despite the recent attempt to identify specific active ingredients of effective interventions for depression, it is still unclear which of these active ingredients (and their combinations/interactions) are the most relevant to prevent depression across childhood and adolescence. For this reason, new statistical approaches, including predictive modelling are required and will help advance the field of early intervention in depression.
Therefore, the main purpose of this research proposal will be to characterize the most relevant active ingredients (and their combination) that prevent the development of persistent high levels of depression across adolescence and young adulthood. More specifically, we will aim to answer to the following main research questions: "What combination/s of active ingredients prevent the development of persistent high levels of depression across adolescence and young adulthood?"
To do this, we will use the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort, which is a longitudinal birth cohort study, set in the UK, examining the determinants of development, health and disease during childhood and beyond.