Activation/inhibition in major depressive episodes of unipolar, bipolar, and borderline patients measured with the multidimensional assessment of Thymic States (MAThyS)

• We investigated the MATHyS among patients with unipolar or bipolar depression. • Major depressive patients with borderline personality disorder were also included. • Internal consistency of MAThyS was good (α = 0.78–0.88) in all the patient groups. • Validity of MAThyS in assessing activation and emotional reactivity still unclear. Major depressive episodes (MDEs) are phenomenologically heterogeneous. The Multidimensional Assessment of Thymic States (MAThyS) scale was developed to estimate activation/inhibition, emotional reactivity, and to differentiate types of depression in bipolar disorder (BD). Their role in diagnosis or other depressions remains unclear. We assessed validity of Finnish translation of the MAThyS in 94 patients with Major Depressive Disorder (MDD), MDE/BD, or MDE/BPD (MDE comorbid with Borderline Personality Disorder), and 29 healthy controls. We examined the associations of MAThyS total score with depression severity (MADRS), (hypo)manic symptoms (YMRS, MIXMDE), and BPD severity (BPDSI), assessed internal consistency, and conducted confirmatory factor analysis to test the postulated two-factor structure. MAThyS demonstrated good internal consistency in patient subcohorts (Cronbach’s α = 0.78–0.88), but not in controls (α = 0.19). In hierarchical regression model (adjusted R² = 0.34), MAThyS total score was negatively associated with depression severity (MADRS) (β = –0.316, p = 0.003), but positively with mixed symptoms (MIXMDE; β = 0.319, p = 0.017), borderline severity (BPDSI; β = 0.195, p = 0.13) and momentary (hypo)manic symptoms (YMRS; β = 0.171, p = 0.15). The two-factor model had poor fit (CFI = 0.687; RMSEA = 0.125). The Finnish MAThyS translation retains good internal consistency, for total scores assessed in MDE patient subgroups, but validity of the scale in assessing activation and emotional reactivity specifically remains unclear. MAThyS may aid in detecting signs of increased activation and mixed features. Further studies are needed to evaluate its validity and clinical utility.