The Role of Insulin- Like Growth Factor-1 in Schizophrenia By Karen Kiernan

Aim of Article Schizophrenia - Impaired Glucose Tolerance - Insulin Resistance - Type 2 Diabetes Mellitus  Antipsychotics?

Aim of Article Role of IGF-1 deficiency - Insulin Resistance - Pathogenesis of Schizophrenia

IGF-1 Protein Hormone Similar structure to Insulin Stimulates cell growth Inhibits apoptosis

Experiment Patients with Schizophrenia - no previous treatment with psychotropic medication Healthy Comparison Subjects Low risk of Diabetes

Simplified Indian Diabetes Risk Score Age [years] < ≥ Abdominal obesity Waist <80 cm [female], <90 [male] 0 Waist ≥ 80 – 89 cm [female], ≥ 90 – 99 cm [male] 10 Waist ≥90 cm [female], ≥ 100 cm [male] 20 Physical activity Exercise [regular] + strenuous work 0 Exercise [regular] or strenuous work 20 No exercise and sedentary work 30 Family history No family history 0 Either parent 10 Both parents 20 Minimum score 0 Maximum score 100

Method 12 hour overnight fast - Glucose - Insulin - IGF-1

Results Schizophrenia Patients - Glucose – Similar to healthy subjects - High Insulin - Low IGF-1 - High Insulin Resistance - Negative correlation between Insulin and IGF-1

Connection with Schizophrenia? Deficiency of IGF-1 - Increased incidence of DM among patients with Schizophrenia - Pathogenesis of Schizophrenia itself?

IGF-1 deficiency Low Birth Weight Leanness Decrease in stature All indicate increase risk of Schizophrenia Also - Negative Cancer correlation

Genetics Chromosome 12p13-q13 - Linked with Schizophrenia - Close to gene coding for IGF-1

Pathogenesis IGF-1 Neuro-protective Anti-apoptotic effect Crucial for optimal neurodevelopment

Specific Hypothesis High concentrations of IGF-1 receptors in Hippocampus Hippocampus dysfunction in Schizophrenia - Auditory Hallucinations Higher deficiency of IGF-1 - More severe Auditory Hallucinations

Conclusion Strong evidence of link More studies needed!

Thank you for your attention

Source Insulin and Insulin like growth factor1 anormalities in antipsychotic naive schizophrenia American Journal on Psychiatry, October 2007