The present invention provides methods and systems or apparatuses, to analyze multiple molecular and clinical variables from an individual diagnosed with a psychiatric disorder, such as post-traumatic stress disorder (PTSD), in order to optimize medication selection for therapeutic response. Molecular co-variables include polymorphisms in genes including those involved in central control and mediation of the hypothalamic-pituitary axis (HPA) stress response, the density of methylation in regulatory regions of said polymorphic genes, polymorphisms in genes that encode cytochrome P450 enzymes responsible for drug metabolism, and drug-drug and drug-gene interactions. Clinical co-variables include but are not limited to the sex, age and ethnicity of that individual, medication history, family history, diagnostic codes, Pittsburgh insomnia rating score, and Charlson index score. The system makes a determination based on unstructured and structured data types derived from internal and external knowledge resources to determine psychotropic drug choice that best matches the molecular and clinical variation profile of an individual patient. The decision support system provides a therapeutic recommendation for a clinician based on the patient's variation profile.