Do Antipsychotics Block Insulin Action in the Brain: is it a Class Effect?

Launched by CENTRE FOR ADDICTION AND MENTAL HEALTH · Jul 31, 2025

Keywords

ClinConnect Summary

This clinical trial is studying how a medicine called haloperidol, which is used to treat mental health conditions like schizophrenia and bipolar disorder, might affect how insulin works in the brain. Insulin is a hormone that helps control sugar levels in the body and also plays a role in how the brain processes information and thinks. Some antipsychotic medicines, including haloperidol, can cause side effects like weight gain and diabetes when used for a long time. This study aims to understand if and how haloperidol might interfere with insulin’s action in the brain, which could help researchers find ways to reduce these side effects in the future.

The study is looking for healthy adults between 18 and 35 years old who have a normal body weight and no history of mental illness, diabetes, or other health problems that affect insulin or metabolism. Participants must be able to give informed consent, meaning they understand the study and agree to take part. Women who are pregnant, breastfeeding, or using hormonal birth control are not eligible. If you join the study, you can expect to follow specific procedures, including tests to check your insulin sensitivity and brain function. The study is currently not yet recruiting but aims to include both men and women who meet the criteria. This research could help improve the safety of antipsychotic medications for people who need them.

Gender

ALL

Eligibility criteria

• Inclusion Criteria:
• • 1. Must be deemed to have the capacity to provide informed consent
• • 2. Must sign and date the informed consent form
• • 3. Stated willingness to comply with all study procedures;
• • 4. Age: 18-35
• • 5. Body Mass Index (BMI) 18.5-24.9 kg/m2
• • 6. Both sexes
• Exclusion Criteria:
• • 1. History of psychiatric illness, including any substance use (screened using the Mini International Neuropsychiatric Interview (MINI))
• • 2. Pre-diabetes or diabetes (fasting glucose ≥6.0 mmol/L, HbA1c\>6% or use of anti-diabetic drug),
• • 3. Evidence of impaired insulin sensitivity, assessed using the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) ≥2.5
• • 4. Family history of diabetes in a first degree relative (parent or sibling)
• • 5. Use of weight reducing agents
• • 6. History of kidney or liver disease
• • 7. History of cell blood disorders
• • 8. Irregular menstrual cycles (e.g., menstruation occurs less than 21 days or more than 35 days apart, or not having menstruated for three months (or 90 days), or conditions such as endometriosis or polycystic ovary syndrome (PCOS) or prior surgical interventions such as a hysterectomy or oophorectomy)
• • 9. Current use of hormonal birth control (e.g., pill, patch, hormonal intrauterine device \[IUD\], ring). Participants must have had at least 2 regular menstrual cycles following the discontinuation of hormonal birth control \[50\]
• • 10. Current use of progesterone, estrogen, testosterone, or fertility treatment.
• • 11. Pregnant, gave birth in the last year, or breastfeeding. Participants must have at least 3 regular menstrual cycles post-breastfeeding before beginning the study.
• • 12. Major medical or surgical event within the last 6 months
• • 13. Contraindications for MRI, including metal implants, pacemakers, cochlear implants, claustrophobia, weight \>250 lbs
• • 14. Any contraindications to the investigational products as listed in the product monographs including known hypersensitivity to the drug or the excipients of the product (note: enzymatic lactose intolerance is NOT exclusionary),
• • 15. Any medications that increases risk of hypoglycemia or could contribute to hyperglycemia
• • 16. Any medical conditions that constitute as a warning/precaution for haloperidol, lorazepam, benztropine, or insulin.
• • 17. Use of any of the prohibited medications listed in the product monograph of haloperidol, lorazepam, benztropine, or insulin (Pheochromocytoma, barbiturates, and narcotics are exclusionary, any use of painkillers and antihistamines must be reviewed by PI but are not exclusionary