An Examination of Psychological Pain, Alexithymia, and Chronotype in Depressive Disorder within the Framework of the Interpersonal Theory of Suicide

Background: Major depressive disorder (MDD) is strongly associated with increased suicide risk, with psychological pain considered an important experiential dimension related to suicide vulnerability. Within the framework of the Interpersonal Theory of Suicide (IPTS), perceived burdensomeness, thwarted belongingness, and acquired capability for suicide are key interpersonal constructs associated with suicidal ideation and behavior. In addition, alexithymia and chronotype have also been linked to depression and suicidality.Methods: This cross-sectional study included 121 patients with MDD and 141 healthy controls. Participants completed the Beck Depression Inventory, Psychache Scale, Toronto Alexithymia Scale, Morningness–Eveningness Questionnaire, Interpersonal Needs Questionnaire, and Acquired Capability for Suicide Scale. Group comparisons, correlation analyses, and multiple linear regression analyses were performed.Results: Compared with controls, individuals with MDD showed higher levels of psychological pain, depressive symptoms, alexithymia, interpersonal unmet needs, and acquired capability for suicide, and were more likely to exhibit an evening chronotype. Psychological pain was positively associated with depressive symptoms, perceived burdensomeness, thwarted belongingness, alexithymia, and acquired capability for suicide. In the multivariable model, perceived burdensomeness showed the strongest association with psychological pain, followed by depressive symptom severity and thwarted belongingness.Conclusion: Psychological pain in MDD appears to be closely associated with interpersonal unmet needs, particularly perceived burdensomeness. These findings highlight the importance of evaluating psychological pain together with IPTS-related interpersonal constructs in comprehensive clinical assessments of individuals with depression.