High-sensitivity C-reactive protein as an early transdiagnostic biomarker for thoughts of death in mood disorders

Introduction: Individuals with affective disorders have been consistently found to exert chronic low-grade inflammation, particularly, increased C-reactive protein (CRP) hematic levels were observed in major depressive disorder (MDD) patients. Moreover, an association between suicidal behaviour and increased CRP hematic levels has been documented. Few studies specifically investigated all suicidality spectrum dimensions, by recruiting all affective disorders, e.g. MDD, bipolar disorder type-1 (BD-I), bipolar disorder type-2 (BD-II) and cyclothymic mood disorder (Cyc). Therefore, our study was designed to explore the association between a low-grade inflammatory state (as assessed by high-sensitivity CRP [hsCRP]) and all suicidal spectrum dimensions across affective spectrum disorders in a real-world setting. Methods: A naturalistic observational cross-sectional study was carried out by retrospectively recruiting 225 adult inpatients with affective disorders (MDD, BD-I, BD-II, Cyc). As routine clinical practice, for all patients were collected: a) hsCRP levels within a full laboratory panel; b) anthropometric measures; c) short version of the MINI Suicidal Scale (MINI-5-s); d) short version of the Temperament Evaluation of the Memphis, Pisa, Paris and San Diego (brief-TEMPS-M). Results: Within the total sample, 62.2 % reported thoughts of death in the last month, while 55.6 % experienced current suicidal ideation. According to a logistic regression model, thoughts of death were significantly predicted by higher score at the depressive subscale of TEMPS-M (Exp(B) = 1.069; 95 %IC = 1.021-1.119; p = 0.005) and higher hsCRP levels (Exp(B) = 1.818; 95 %IC = 1.053-3.139; p = 0.032). Conclusions: Our findings suggest that hsCRP could potentially represent a relatively easy, cheap and early transdiagnostic inflammatory biomarker for suicidality across mood disorders, particularly among those displaying a predominant affective depressive temperament. Further studies should longitudinally explore clinical implication derived by the stratification of mood disorders according to the inflammatory pattern, as well as testing whether anti-inflammatory therapy could represent an early treatment strategy for managing suicidality risk.