The Role of InsulinLike Growth Factor1 in Schizophrenia

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The Role of Insulin-Like Growth Factor-1 in
Schizophrenia

• By Karen Kiernan

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Aim of Article

• Schizophrenia
• - Impaired Glucose Tolerance
• - Insulin Resistance
• - Type 2 Diabetes Mellitus
• Antipsychotics?

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Aim of Article

• Role of IGF-1 deficiency
• - Insulin Resistance
• - Pathogenesis of Schizophrenia

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IGF-1

• Protein Hormone
• Similar structure to Insulin
• Stimulates cell growth
• Inhibits apoptosis

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Experiment

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

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Simplified Indian Diabetes Risk Score

• Age years
• lt 35 0
• 35 - 49 20
• 50 30
• Abdominal obesity
• Waist lt80 cm female , lt90 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

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Method

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

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Results

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

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Connection with Schizophrenia?

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

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IGF-1 deficiency

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

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Genetics

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

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Pathogenesis

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

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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

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Conclusion

• Strong evidence of link
• More studies needed!

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• Thank you for your attention

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Source

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