Trigeminal Nerve Stimulation in Treatment-resistant Generalized Anxiety Disorder: a Feasibility Study

Trigeminal Nerve Stimulation in Treatment-resistant Generalized Anxiety Disorder: a Feasibility Study

This is a feasibility study for trigeminal nerve stimulation (TNS) in patients with treatment-resistant generalized anxiety disorder (TR-GAD). Ten participants will receive TNS for 8 weeks as an augmentation strategy to pharmacological treatment for generalized anxiety disorder (GAD).

• The primary objective is to ascertain if TNS is a safe and well-tolerated treatment for patients with TR-GAD.
• The secondary objective will be to monitor changes in GAD symptom severity throughout the study.

Results from this study will inform a randomized controlled trial to be conducted in the future.

Inclusion Criteria:

• Meet the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM5) criteria for generalized anxiety disorder.
• Subjects on a stable dose of an selective serotonin reuptake inhibitor (SSRI) or serotonin and noradrenaline reuptake inhibitor (SNRI) for at least 8 weeks.
• Treatment-resistant - treatment resistance will be defined as lack of response to at least two drugs, from two different classes of drugs considered first-line or second-line for GAD. Only trials lasting at least 8 weeks, and with at least the minimum effective dose of the given medication will be considered failed trials.

Exclusion Criteria:

• Moderate to severe major depressive disorder
• Moderate to high suicidality
• Diagnosis of obsessive compulsive disorder (OCD), PTSD, bipolar disorder, schizophrenia, schizoaffective disorder, personality disorders, substance use disorders, intellectual disabilities and dementia or other neurological diseases including trigeminal neuralgia
• Pregnant or breastfeeding women
• Participants who are experiencing seizures
• Implanted vagal nerve stimulation (VNS) or other electrical devices
• Participants who are already undergoing transcutaneous electrical nerve stimulation
• Consumption of cannabis, any cannabis by-products, illicit drugs, or alcohol above 3 drinks per week
• Consumption of natural health products that may affect anxiety or depression symptoms