Clinical Review

Brain drugs of the future

BMJ 1998; 317 doi: http://dx.doi.org/10.1136/bmj.317.7174.1698 (Published 19 December 1998) Cite this as: BMJ 1998;317:1698
  1. Susan Greenfield, professor
  1. Department of Pharmacology, University of Oxford, Oxford OX1 3QT

    People have been using drugs to alter brain states since the dawn of time. But the use of specific drugs to combat specific brain problems is a hallmark of this century. In previous eras doctors reached for laudanum to combat hysteria, oblivious to the underlying neurochemistry. However, in Paris the famous neurologist Charcot purposely gave belladonna to patients with Parkinson's disease to combat the constant salivation that accompanies loss of motor control because women of the time who used the drug to dilate their pupils complained of a dry mouth. Surprisingly, this anticholinergic drug proved effective in combating not just the dribbling but the motor symptoms of Parkinson's disease.

    Magnetic resonance scan of coronal section of brain in Parkinson's disease

    Today we owe much to the work of Henry Dale and Otto Loewi, who established that chemicals act as transmitters to relay a signal from one neurone to the next.1 The guiding principle of modern neuropharmacology is to mimic, block, amplify, or reduce the availability of certain transmitters, believed to be pivotal to the disease to be treated. Yet herein lies the problem.

    Summary points

    One transmitter may be linked to many disorders, and one disorder to many transmitters

    Classic transmitters have non-classic modulatory functions too

    Substances such as nitric oxide and acetylcholinesterase have unexpected signalling properties

    Neurodegeneration might be an aberrant form of development, so drugs promoting neuronal regeneration should be approached with caution

    Drugs in the future could be used as a Rosetta stone for linking brain and mind

    The promiscuous transmitter

    There is no one to one matching of a single chemical system to a disease. Consider, for example, the well known transmitter dopamine. In Parkinson's disease there is a deficit of dopamine in the substantia nigra, hence prompting administration of the precursor and eventual mimicry of the effects of dopamine …

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