interesting:
http://en.wikipedia.org/wiki/KetamineThe National Institute of Health News reports that a study of 18 patients has found that ketamine significantly improved treatment-resistant major depression within hours of injection.[24] The improvement lasted up to one week after the single dose.[25] The patients in the study were previously treatment resistant, having tried an average of six other treatments that failed. NIMH director Dr. Thomas Insel said in the paper:
"To my knowledge, this is the first report of any medication or other treatment that results in such a pronounced, rapid, prolonged response with a single dose. These were very treatment-resistant patients."
The researchers apparently attribute the effect to ketamine being an NMDA receptor antagonist.[26] Those findings of Zarate et al corroborate earlier findings by Berman et al.[27] However Zarate et al do raise some concerns about their results due to a possible lack of blinding, because of the inebriating effects of low dose ketamine infusion, and it is recommended that future studies include an active placebo.
The findings by Zarate et al. are confirmed by Liebrenz et al, who substantially helped a 55-year-old male subject with a treatment-resistant major depression and a co-occurring alcohol and benzodiazepine dependence by giving an intravenous infusion of 0.5 mg/kg ketamine over a period of 50 minutes and Goforth et al who helped a patient with severe, recurrent major depressive disorder that demonstrated marked improvement within 8 hours of receiving a preoperative dose of ketamine and one treatment of electroconvulsive therapy with bitemporal electrode placement.[28]<[29]
However, a new study in mice by Zarate et al. shows that blocking the NMDA receptor is an intermediate step. According to this study, blocking NMDA increases the activity of another receptor, AMPA, and this boost in AMPA activity is crucial for ketamine’s rapid antidepressant actions. NMDA and AMPA are receptors for the neurotransmitter glutamate. The glutamate system has been implicated in depression recently. This is a departure from previous thinking, which had focused on serotonin and norepinephrine. The glutamate system may represent a new avenue for treatment and research.[30]