The goal of this observational study is to learn about the effects of early-life adversity (ELA) on the composition of children's microbiome and on their psychosocial functioning. The main questions it aims to answer are:

• Do children who have experienced ELA have lower gut microbial diversity and/or an altered gut microbial composition?
• Do these microbiome alterations correlate with adverse neurodevelopmental outcomes, including increased levels of stress, social and/or affective problems?

Inclusion Criteria:

• Primary school-aged children (6 to 13 years of age) who have experienced at least one early-life traumatic event, based on the Childhood Trust Events Survey (CTES) questionnaire
• The child and at least one of his/her parents (or guardian) speak Dutch sufficiently well to complete all of the questionnaires and the semi-structured child psychiatric interview (SCID-5-Junior)

Exclusion Criteria:

• any chronic disorders or diseases known to affect the gut micobiome
• inablity to complete questionnaires and/or semi-structured interview because of linguistic and/or cognitive barrier
• congenital or acquired immunodeficiencies
• use of medication(s) that affect gastrointestinal function (e.g., antibiotics) within the last 6 weeks, or laxatives within the last 4 weeks, or probiotic or prebiotic supplements within the last 4 weeks
• current involvement in another clinical or food study

Primary school-aged children (6 to 13 years of age) who have been referred to the UZ Brussel child and adolescent psychiatry department