LAUSR

Abstract Objectives Accumulating evidence suggests that the effects of ketamine administered intravenously at subanaesthetic doses on both anhedonic symptoms and suicidal ideation occur independently of depressive symptoms in major depressive disorder (MDD) and bipolar disorder (BD). This study sought to determine the relationship between anhedonia and suicidal ideation after serial ketamine infusions. Methods A total of 79 subjects with either treatment-refractory MDD (n = 60) or BD (n = 19) were included in a clinical ketamine study. The Montgomery–Åsberg Depression Rating Scale (MADRS) anhedonia factor and the first five items of the Scale for Suicidal Ideations (SSI-Part I) were used to assess anhedonia symptoms and suicidal ideation, respectively. Results At baseline, anhedonia, as measured by the MADRS, was not significantly associated with suicidal ideation or specific suicide-related ideation as measured by SSI-Part I (all p’s > 0.05). Only the ‘wish to die’ and ‘desire to make a suicide attempt’ items were positively associated with anhedonia at two weeks after the sixth ketamine infusion, which was independent of the reductions in depressive symptoms (all p’s < 0.05). Conclusion Anhedonia as measured by the MADRS appeared to not be positively related to suicidal ideation after serial ketamine infusions. KEY POINTS Serial ketamine (0.5 mg/kg) infusions have shown quick and dramatic antisuicidal and antianhedonic effects in patients with depression. The association between anhedonia and suicidal ideation after serial ketamine infusions is unclear. Anhedonia appeared to not be positively related to suicidal ideation after serial ketamine infusions.