The use of Ketamine to treat Major Depressive Disorderplugin-autotooltip__plain plugin-autotooltip_bigMajor Depressive Disorder

Major Depressive Disorder (MDD), also known simply as 'depression', is a mental disorder characterized by at least two weeks of pervasive low mood.

Current estimates are that severe depression affects around 2% of the global population at any given time, currently more than 150 million. The majority of cases don't appear to have an obvious personal and/or societal cause. was formally investigated in a 2006 report for JAMA Psychiatry. A team based at the US National Institute of Mental Health (NIMH) in Bethesda, Maryland, found that :

Robust and rapid antidepressant effects resulted from a single intravenous dose of an N-methyl-D-aspartate antagonist; onset occurred within 2 hours postinfusion and continued to remain significant for 1 week."

To our knowledge, there has never been a report of any other drug or somatic treatment (ie, sleep deprivation, thyrotropin-releasing hormone, antidepressant, dexamethasone, or electroconvulsive therapy) that results in such a dramatic rapid and prolonged response with a single administration."

The mechanism of its action, however, is still unknown.

A new (2017) study, covered in Nature suggests that a previous theory (that it inhibits the brain's NMDA-receptors) may be incorrect.

Their finding adds to recent studies contradicting a long-held idea that the drug works mainly by blocking proteins called NMDA receptors, on the surface of brain cells, which transmit signals between those cells."

A third (also as yet unproven) theory instead suggests that breakdown chemicals of the drug - rather than the drug itself - may be responsible for its anti-depressant effects.

Note: The 'enantiomer' (i.e. mirror image molecule) of Ketamine is called Esketamine (marketed under the name Ketanest and others) it has similar properties, and is also used to treat depression - also by an unknown mechanism.

Update Oct 2018 : "Johnson & Johnson has submitted its esketamine for regulatory approval, but researchers still don't understand how the fast-acting antidepressant lifts moods." Nature Reviews Drug Discovery volume 17, pages 773–775

Also see: Lithiumplugin-autotooltip__plain plugin-autotooltip_bigLithium (treatment for bipolar disorder)

Lithium, normally in the form of lithium carbonate (Li2CO3) is widely recognised as the 'gold standard' prescribed drug for treating bipolar disorder, depression and mania.

In widespread use since the early 1970s, lithium carbonate was the first and Major Depressive Disorderplugin-autotooltip__plain plugin-autotooltip_bigMajor Depressive Disorder

Major Depressive Disorder (MDD), also known simply as 'depression', is a mental disorder characterized by at least two weeks of pervasive low mood.

Current estimates are that severe depression affects around 2% of the global population at any given time, currently more than 150 million. The majority of cases don't appear to have an obvious personal and/or societal cause. and General Anaestheticsplugin-autotooltip__plain plugin-autotooltip_bigGeneral Anaesthetics

A general anaesthetic is a drug that brings about a reversible loss of consciousness.* [ see note below ]

In formal use since 1842 - the first public demonstration used Diethyl ether to carry out surgery. (Though it's likely that alcohol, another chemical classed as an anaesthetic, was previously used, extensively, for similar purposes).