Study Procedures 

STRATIFY involved participants at the age 18 to 30 years. Assessment, similar to those performed in IMAGEN follow-up 3, included brain scans and fMRI tasks, blood samples, assessments of substance use, cognitive and neuropsychological performance, and clinical diagnostic interviews. Recruitment started in … and was completed 31. December 2020.  

COVID-19 Follow-Up STRATICO 

Included participants of the STRATIFY pool were re-contacted for the STRATICO questionnaire and were asked to fill out on first a bi-weekly (1st Lockdown phase) to a three-month (2nd Lockdown phase) basis a questionnaire including questions specifically to the COVID-19 exposure, behavioral and symptomology changes, and alterations in daily life, substance use, media consumption. COVID-19 questions are based on the Crisis questionnaire by the NIH ( ). First COVID-19 assessments were performed in April 2020 and are currently ongoing.