To evaluate if intranasal insulin is effective in reducing PTSD symptoms.

The current proposal aims to study the pharmacotherapeutic effects of intranasal insulin on PTSD symptoms and inhibition of amygdala hyperactivation in subjects with PTSD.

Inclusion Criteria:

• Male or female, 21-65 years old
• Current PTSD
• Able to provide written informed consent

Exclusion Criteria:

• Unstable medical condition, clinically determined by a physician
• Diabetes requiring insulin or oral hypoglycemic agents
• Moderate-severe traumatic brain injury
• Current psychotic disorder, bipolar disorder, cognitive disorder in the past 12 months
• Current substance use disorders (except alcohol, tobacco, or cannabis) in the past 3 months
• Changes in doses of psychotropic medications in the past 4 weeks
• Initiation of individual therapy or counseling in the past 4 weeks
• Imminent suicidal or homicidal risk
• Contraindication to Insulin
• History of claustrophobia
• Presence of cardiac pacemaker or other electronic device or ferromagnetic metal foreign bodies in vulnerable positions as assessed by a standard pre-MRI safety screening questionnaire