Serotonin and creatine are processed separately in the brain, and deficits in these brain biochemicals lead to distinct clinical problems. Therefore, investigators believe that treatment with a combination therapy, which could correct both deficits, would have a synergistic effect in the treatment of hypoxia-related depression and possibly other forms of treatment-resistant depression. Thus, investigators propose to investigate antidepressant efficacy of dietary 5-hydroxytryptophan (5-HTP) and creatine, as a means to restore the brain neurotransmitter and metabolic imbalances linked to chronic hypoxia caused by high altitude residence.