Which clinical factors and biochemical parameters differentiate major depressive disorder with versus without lifetime psychotic symptoms?

Objective: Major depressive disorder (MDD) is a prevalent disabling condition, with psychotic features complicating its course and management. Purpose of the study is to identify clinical and biochemical factors differentiating psychotic from non-psychotic MDD. Methods: This is a retrospective single-centre study conducted on patients hospitalised between 2002 and 2022 at Fondazione IRCCS Policlinico (Milan, Italy) with a diagnosis of MDD. A large set of clinical and biochemical variables was collected on the first day of hospitalisation. Patients were divided according to the presence or absence of lifetime psychotic symptoms and compared by Student's t-test for continuous variables and Chi-square tests for categorical ones. The statistically significant continuous variables were inserted in a binary logistic regression model as independent predictors of lifetime psychotic symptoms. Results: No statistically significant differences in biochemical parameters (p > 0.05) were found in the two groups. The logistic regression model showed that depressed patients with lifetime psychotic symptoms had a significant longer duration of hospitalisation (p = 0.007), more lifetime suicide attempts (p = 0.035) and higher BPRS scores (p = 0.004) than the counterpart. Conclusions: Lifetime psychotic symptoms confer a more severe course of illness in patients with MDD. No biochemical parameter resulted as a biomarker of MDD psychotic subtype.