Cohort profile: The Trondheim Early Secure Study (TESS) – A study of mental health, psychosocial development and health behaviour from preschool to adolescence

​Many mental health disorders in childhood and adolescence are already evident by the preschool years,1–3 but there is little empirical research concerning the prevalence and predictors of psychiatric disorders in young children. If left undetected, child problems may deteriorate and, with time, become more resistant to ​change.4 Identifying risk factors, co-occurrence of difficulties, developmental trajectories and potential causal mechanisms can aid researchers and clinicians in preventing, diagnosing and treating mental health problems in children. A true community study using structured diagnostic tools, which are the preferred methods for diagnosis in all age groups and correspond to medical decision making, had not been published when the Trondheim Early Secure Study (TESS) was established in 2007.

Of note, other comprehensive longitudinal community studies of mental health problems in young children did exist at that time, such as the Dunedin study5 and the Stony Brook Temperament Study;6 however, these studies did not apply diagnostic interviews to assess children’s psychopathology. Subsequently, other prospective studies using clinical interviews to assess a wide spectrum of psychiatric disorders, beginning in the preschool years, were launched, perhaps most notably the Factors of Vulnerability to Psychopathology (Barcelona; 2010)7 and the Leipzig Developmental Study (Leipzig; 2010).