The goal of this feasibility study is to determine the tolerability and safety of add on treatment with L-methylfolate in patients with treatment-resistant generalized anxiety disorder (GAD). The primary objective is to monitor for side effects and other risks associated with the treatment. Secondary objectives are to compare the severity of symptoms, serum levels of folate, vitamin B12, C-reactive protein, homocysteine, tumor necrosis factor alpha and interleukin 6 before and after treatment. Participants will continue with their usual treatment for GAD and receive add on treatment with L-methylfolate 15 mg per day for 8 weeks. All participants will receive the same intervention.
Adults.
Patients on a stable dose of an selective serotonin uptake inhibitors (SSRI) or serotonin and noradrenaline reuptake inhibitors (SNRI) for at least 8 weeks.
Treatment-resistant GAD, defined by lack of response to at least two drugs, from two different classes of drugs considered first-line or second-line for GAD according to the Canadian Clinical Practice Guidelines for the Management of Anxiety, Posttraumatic Stress and Obsessive-Compulsive Disorders (Katzman et al., 2014). Only trials lasting at least 8 weeks and with at least the minimum effective dose of the given medication will be considered failed trials.
Patients with moderate to severe major depressive disorder based on the Patient Health Questionnaire - Nine Item (PHQ-9) scale (score of 15 or above) at baseline.
Mini International Neuropsychiatric Interview version (MINI) 7.0 indicates moderate to high current suicidality or "suicide likely in near future" or current suicidal behavior disorder.
Patients diagnosed with obsessive-compulsive disorder (OCD), bipolar disorder, schizophrenia, schizoaffective disorder, personality disorders, substance use disorders, intellectual disabilities, dementia, epilepsy or other severe neurological diseases.
Patients with cardiovascular diseases, infections, inflammatory diseases, recent surgeries, recent physical trauma and other medical issues that could produce elevation of c-reactive protein (CRP) or homocysteine.