- Gamma-Hydroxybutyric acid (GHB) has been used by some as an antidepressant. Claude Rifat, a French biologist, conducted some early research into GHB's antidepressant potential. Rifat noted that GHB did not cause the emotional blunting effects caused by conventional antidepressants, but instead intensified pleasurable and rewarding feelings in the user while powerfully suppressing depression. However, GHB has now been outlawed, except for use as a prescription treatment for narcolepsy.
- NMDA antagonists such as ketamine and dextromethorphan have recently gained some interest in this field as their apparent ability to reverse opioid tolerance, and can give fast-acting dramatic effects. However, their acute psychoactive effects have been a problem.
- Memantine, a moderate affinity NMDA antagonist, has been used to avoid tolerance buildup, and has seen use in opioid tolerance reversal. Proglumide is used to induce acute reversal of tolerance prior to this maintenance strategy; it does not work by itself in the long term, due to tolerance to its effects.
- Marijuana – The use of marijuana, in moderation, has shown to be of benefit in severely depressed patients. Many people that do not respond well to the use of traditional antidepressants, or who do not like the many unpleasant side effects, prove to do rather well using this plant in moderation
were commonly used as antidepressants until the mid-1950s, when they
fell out of favor with medical orthodoxy due to their addictive nature,
tolerance buildup issues and their side-effect profile. Today the use of
opioids in treating depression is a large taboo in the medical field
due to associations with drug abuse; hence, research has proceeded at a
very slow rate. A small clinical trial conducted at Harvard Medical School in 1995, demonstrated that a majority of treatment-refractory, unipolar, non-psychotic, major depression patients could be successfully treated with an opioid medication called Buprenorphine, which is a partial μ-agonist and potent κ antagonist. The exact mechanism of its action in depression is not known, as κ (kappa) antagonists are antidepressants in their own right.
In 2006, The Journal of European Neuropsychopharmacology published a follow-up study to the 1995 Harvard experiment, with results consistent with the original Harvard findings. Eleven severely depressed patients, refractory to all the conventional depression treatments, were given small doses of buprenorphine. Most of these patients found the buprenorphine to be of significant benefit. The researchers theorized that "Possibly, the response to opiates describes a special subtype of depressive disorders e.g. corresponding to a dysregulation of the endogenous opioid system and not of the monaminergic system."
Another scientific paper was published in the American Journal of Psychiatry in 1999, detailing how researchers found Oxycodone/Oxymorphone to help 5 out of 6 "incurable" refractory severe depression patients.
Buprenorphine was found to be effective as a treatment for depression in patients that had responded to neither antidepressants nor electroconvulsive therapy.
- Anti Depressants
Antidepressants are statistically superior to placebo but their overall effect is low-to-moderate. In that respect they often did not exceed the National Institute for Health and Clinical Excellence criteria for a "clinically significant" effect. In particular, the effect size was very small for moderate depression but increased with severity reaching "clinical significance" for very severe depression. These results were consistent with the earlier clinical studies in which only patients with severe depression benefited from either psychotherapy or treatment with an antidepressant, imipramine, more than from the placebo treatment. Despite obtaining similar results, the authors argued about their interpretation. One author concluded that there "seems little evidence to support the prescription of antidepressant medication to any but the most severely depressed patients, unless alternative treatments have failed to provide benefit." The other author agreed that "antidepressant 'glass' is far from full" but disagreed "that it is completely empty". He pointed out that the first-line alternative to medication is psychotherapy, which does not have superior efficacy.
Antidepressants in general are as effective as psychotherapy for major depression, and this conclusion holds true for both severe and mild forms of MDD. In contrast, medication gives better results for dysthymia. The subgroup of SSRIs may be slightly more efficacious than psychotherapy. On the other hand, significantly more patients drop off from the antidepressant treatment than from psychotherapy, likely because of the side effects of antidepressants. Successful psychotherapy appears to prevent the recurrence of depression even after it has been terminated or replaced by occasional "booster" sessions. The same degree of prevention can be achieved by continuing antidepressant treatment.
Two studies suggest that the combination of psychotherapy and medication is the most effective way to treat depression in adolescents. Both TADS (Treatment of Adolescents with Depression Study) and TORDIA (Treatment of Resistant Depression in Adolescents) showed very similar results. TADS resulted in 71% of their teen subjects having a "much" or "very much" improvement in mood over the 60.6% with medication alone and the 43.2% with CBT alone. Similarly, TORDIA showed a 54.8% improvement with CBT and drugs verses a 40.5% with drug therapy alone.