Yes, there has been a shocking lack of progress in developing transformative psychiatric medicine (We need new drugs for mental ill-health, 5 February), but this may be because in mental health, drugs are not always the answer (see, for example, Richard P Bentall's Doctoring the Mind). Huge progress has been made in the effectiveness of talking therapies for example, free effective treatment for post-traumatic stress disorder (PTSD) is available to all UK army veterans through the charity PTSD Resolution.
The standard explanation is that ketamine blocks NMDA receptors. These receptors bind glutamate, which is a chemical messenger found throughout the brain and body. By blocking NMDA receptors, ketamine increase "brain-derived neurotrophic factor" (BDNF), a protein which I refer to as "Miracle-Grow for the brain." BDNF promotes neuroplasticity-which is the growth of new connections (synapses) in the brain. This has traditionally been viewed as the primary mechanism responsible for ketamine's therapeutic benefits. But ketamine does so much more!