No effect of adjunctive, repeated dose intranasal insulin treatment on body metabolism in patients with schizophrenia.

OBJECTIVE: This study examined the effect of adjunctive intranasal insulin therapy on body metabolism in patients with schizophrenia.

METHOD: Each subject had a DSM-IV diagnosis of schizophrenia or schizoaffective disorder and had been on stable dose of antipsychotic agent for at least one month. In an 8-week randomized, double-blind, placebo-controlled study, subjects received either intranasal insulin (40 IU 4 times per day) or placebo. The whole body dual-energy X-ray absorptiometry (DXA) was used to assess body composition. Lipid particles were assessed using nuclear magnetic resonance (NMR) spectroscopy. All assessments were conducted at baseline, and repeated at week 8.

RESULTS: A total number of 39 subjects completed the study (18 in the insulin group, 21 in the placebo group). There were no significant differences between the two groups in week 8 changes for body weight, body mass index, waist circumference, as well as various measures of lipid particles (p's>0.100). The DXA assessment showed no significant differences between the two groups in week 8 changes for fat mass, lean mass or total mass (p's>0.100).

CONCLUSION: In the present study, adjunctive therapy of intranasal insulin did not seem to improve body metabolism in patients with schizophrenia. The implications for future studies were discussed.