A randomized, double-blind, placebo-controlled, crossover trial evaluating the effect of intranasal insulin on cognition and mood in individuals with treatment-resistant major depressive disorder.

Abstract Background Cognitive dysfunction in major depressive disorder (MDD) is identified as a primary therapeutic target; no current treatment is approved for the treatment of cognitive dysfunction in MDD. We examined whether intranasal insulin offered a beneficial effect across measures of cognitive function in adults with MDD. Methods Thirty-five adults (18–65 years of age: 47.09±9.89) meeting criteria for a major depressive episode as per the Diagnostic and Statistical Manual (DSM)-IV-Treatment Revised were included in this randomized, double blind, placebo-controlled, crossover design study. Subjects were not stratified based on baseline cognitive deficit. Subjects were randomized to 4 weeks of either intranasal insulin 40 International Units (IU) taken four times a day (i.e., morning, afternoon, evening, and before bed) (QID) (n=19) or placebo (n=16). Results No between group differences were observed in change from baseline on total Montgomery Asberg Depression Rating Scale (MADRS) score (25.98±2.81), in either of the Positive or Negative subscales of the Positive and Negative Affect Schedule (PANAS), or on a global index of neurocognition. The possibility of practice and/or carry over effect could not be excluded. Methodological refinement (e.g., stratification of subjects based on baseline cognitive deficit) may have augmented assay sensitivity. Conclusion Intranasal insulin did not demonstrate statistically significant improvements on overall mood, aspects of emotional processing, neurocognitive function, or self-reported quality of life patient reported outcomes.