Study procedure
Depression
After a screening visit to check their eligibility, participants (all outpatients) were invited to two further visits, the baseline and the week 4 visit (end of treatment). Within 1 month from the screening visit, eligible patients came back for the baseline visit and were randomized to minocycline or placebo (1:1) in addition to their current antidepressant. In the same day, we collected a blood sample for measurement of biological markers, including the inflammatory markers and the KP metabolites, and a clinical assessment including the Beck Depression Inventory II (BDI-II) (The final number of randomized patients was 44 (22:22). Five withdrew for different reasons (2 experienced side effects, 1 was lost in follow-up and 1 withdrew for unknown reasons in the minocycline group; 1 patient in the placebo group left for family issues); thus, the final sample consisted of 39 patients, 18 in the minocycline group and 21 in the placebo group. The consort flow diagram for RCTs is shown in our previous publication (