Evaluation of IGF-1 as a novel theranostic biomarker for schizophrenia

In the current study, we aimed to investigate fasting plasma levels of glucose, insulin, growth hormone, IGF-1, and lipid profile in remission schizophrenia patients, treatment resistant schizophrenia patients and healthy controls and to determine whether IGF-1 levels can be used as a theranostic biomarker in schizophrenia.

Sixty-two patients under remission from schizophrenia, sixty-five treatment-resistant patients with schizophrenia and sixty-two healthy controls were included in the study. All patients were recruited and evaluated over 11 months. Symptoms at the time of evaluation were assessed twice using BPRS, PANSS, CGI, and GAF scales by an experienced psychiatrist in accordance with Andreaseen's remission criteria and TRIPS group resistance criteria. Blood samples were collected from all participants to determine fasting glucose, LDL, HDL, Triglyceride, Total Cholesterol, fasting, insulin, GH and IGF-1 levels.

Fasting blood glucose levels were found to be higher in patients with schizophrenia than in healthy controls. Moreover, LDL levels of the treatment sensitive group were higher than that of the treatment resistant group while they were not significantly different from the healthy controls. IGF-1 levels were lower in the treatment sensitive group than in both treatment resistant and healthy control groups. IGF-1, LDL and age of disease onset were found to be significantly associated with treatment resistance in a regression model.

In the present study, remitted patients with schizophrenia could be distinguished from treatment-resistant patients and healthy controls with serum IGF-1, fasting glucose and LDL levels. In addition, we found that smoking and age of disease onset together with IGF-1 levels could significantly predict resistance to treatment.