Post-traumatic stress burden in a sample of hospitalized patients with Bipolar Disorder: Which impact on clinical correlates and suicidal risk? BACKGROUND:  Increasing evidence suggests Bipolar Disorder (BD) to be frequently associated to a history of traumatic experiences and Post-traumatic Stress Disorder (PTSD), with consequent greater symptoms severity, number of hospitalizations and worsening in quality of life. The aim of the present study was to investigate the lifetime exposure to traumatic events and PTSD rates in-patients with BD and to analyze the relationships between PTSD symptoms, clinical characteristics and severity of the mood disorder. METHODS:  A consecutive sample of 212 in-patients with a DSM-5 diagnosis of BD was enrolled at the psychiatric unit of a major University hospital in Italy and assessed by the SCID-5 and MOOD Spectrum-Self Report lifetime version (MOODS-SR). Socio-demographic characteristics, clinical features, substance or alcohol abuse, history of suicide related behaviors were also collected. RESULTS:  Lifetime trauma exposure emerged in 72.3% subjects, with a DSM-5 PTSD diagnosis reported by 35.6%. Patients with PTSD showed more frequently a (hypo)manic episode at onset, alcohol or substance abuse, psychotic features, suicide behaviors, higher scores in almost all the MOODS-SR domains, compared to those without PTSD. LIMITATIONS:  Cross sectional study. Lack of data about the time since trauma exposure or PTSD onset. CONCLUSIONS:  Our findings show a history of multiple traumatic experiences in hospitalized patients with BD besides high rates of PTSD, with the co-occurrence of these conditions appearing to be related to a more severe BD. Detailed investigation of post-traumatic stress symptoms is recommended for the relevant implications on the choice of a tailored treatment and the prognosis assessment.