Analysis

How do psychiatric drugs work?

BMJ 2009; 338 doi: http://dx.doi.org/10.1136/bmj.b1963 (Published 29 May 2009) Cite this as: BMJ 2009;338:b1963
  1. Joanna Moncrieff, senior lecturer1,
  2. David Cohen, professor 2
  1. 1Department of Psychiatry and Behavioural Sciences, University College London, London W1N 8AA
  2. 2School of Social Work, Florida International University, Miami FL 33199, USA
  1. Correspondence to: J Moncrieff j.moncrieff{at}ucl.ac.uk
  • Accepted 3 February 2009

Joanna Moncrieff and David Cohen argue that changing our view of the action of psychiatric drugs would help patients to become more involved with decisions about treatment

Drugs for psychiatric problems are prescribed on the assumption that they mostly act against neurochemical substrates of disorders or symptoms. In this article we question that assumption, proposing that drugs’ action be viewed rather as producing altered, drug induced states, a view we have called the drug centred model of action. We believe that this view accords better with the available evidence. It may also allow patients to exercise more control over decisions about the value of pharmacotherapy, helping to move mental health treatment in a more collaborative direction.

Assumptions about mode of action

The widespread use of psychiatric drugs is justified by the idea that they work by correcting, or helping to correct, underlying biological abnormalities that produce particular psychiatric symptoms. We have called this view the disease centred model of psychiatric drug action (table). Most drugs used in medicine can be understood as working according to a disease centred model—even analgesics, for example, work by acting on the physiological mechanisms that produce pain. In psychiatry, the disease centred model is reflected in the names of the major drug classes: antidepressants are believed to reverse biochemical pathways that give rise to symptoms of depression and antipsychotics are thought to act on mechanisms that produce psychotic symptoms. From this viewpoint, the therapeutic actions of drugs (their actions on disease processes) can be distinguished from other effects, accordingly termed side effects.

View this table:

Models of psychiatric drug action

An alternative, drug centred model of drug action, stresses that psychiatric drugs are, first and foremost, psychoactive drugs. They induce complex, varied, often unpredictable physical and mental states that patients typically experience as global, rather than distinct therapeutic effects and side effects …

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