Abstract: The invention provides a method for determining the outcome of treatment with an antidepressant medication in a patient. In particular, the invention provides a method of screening patients to identify those patients with a decreased risk of non-response to treatment with antidepressant medication comprising: (a) obtaining a sample of genetic material from the patients, and (b) assaying the sample for the presence of a genotype in the patients which is associated with a decreased risk of non-response to treatment with antidepressant medication, wherein the genotype is characterized by a polymorphism in a HTR2A, GRIK4, BCL2, or a combination thereof.