This is a parallel 3-group, multicenter, prospective, randomized, single-blind (evaluator) controlled pilot trial, with a 38- week follow-up. Patients diagnosed with bipolar disorder (BD) according to DSM -5 criteria for mild depression or subsyndromal depressive symptoms are assigned to one of the following 3 treatment groups: 1) psychopharmacological treatment plus Mindfulness Based Cognitive Therapy (MBCT); 2) psychopharmacological treatment plus structured group psychoeducation; 3) treatment as usual (TAU), including standard psychiatric care with standard pharmacologic treatment. After written informed consent is signed, patients meeting the inclusion criteria are randomized (2:2:1 ratio) through a Random Allocation Software. All three groups are assessed at baseline (t0), immediately after completing the program (t1; 8 weeks) and at follow-up six months after randomization. The assessments include the following variables: depression, anxiety, general and social cognition, global functioning, BDNF, and other clinical variables. The evaluator who collected the biomarkers and the clinical and psychometric data will be blind to treatment. The interrater variability between all researchers will be checked.