Treatment of Psychosis and Risk Assessment for Violence



Matthew M. Large, F.R.A.N.Z.C.P.

The American Journal of Psychiatry, VOL. 171, No. 3

March 1, 2014



In the trial of Daniel M’Naghten for the 1843 shooting of the British Prime Minister’s secretary, Edward Drummond, the jury accepted that the defendant was not guilty because he was suffering from a “disease of the mind” and that a resulting “delusion carried him away beyond the power of his own control … over acts which had connexion with his delusion”. While this verdict excited considerable controversy at the time and not all contemporary jurisdictions accept a legal defense of mental illness, it remains conventional wisdom that severe mental illnesses in general and delusions in particular are causally associated with violence. However, not all empirical studies support this association, and the role of delusions remains controversial. For example, a well-known meta-analysis by Bonta et al. found that violent recidivism was less common among those with psychosis than among other released prisoners. In the MacArthur Violence Risk Assessment Study, delusions did not increase the overall probability of violence among patients released from psychiatric hospitals.


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Human Services and Justice Coordinating Committee