Mental Illness and Serious Harm to Others - University of Liverpool

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NHS National Programme on Forensic Mental Health Research and Development standard of design criteria for studies of effectiveness of any given intervention. Requirements to meet the standard included: ❑ being randomised ❑ being clinician-blind and patient-blind ❑ having more than 20 subjects in each group ❑ achieving follow-up (time unspecified) for at least 80 per cent of each group. Just one study was found, in essence of chemical restraint, which met such criteria. It is arguable that more psychological and social strategies are not suitable for double-blind research protocols, but there is no reason why the other criteria could not be met. A further possible problem, however, is that randomisation so restricts the characteristics of samples studied that results may not be applicable to real-life practice. The report goes on to provide much of its guidance based on 'consensus' rather than evidence. In this field, there is much to be drawn from more general literature. The principles enunciated in the National Health Service (NHS) Management Executive (1993) document Risk Management in the NHS remain sound, for this field as for others in health care delivery. John Adams, a geographer who has specialised in transport planning, has provided essential reading in his 1995 book, entitled simply Risk, not least because he appreciates the issues in the round. He shows how risk is often redistributed rather than reduced, while the introduction of some genuine safety measures may have a paradoxical effect. Perhaps the best known example which he cites is that of the Davy lamp. Usually described as one of the most significant safety improvements in the history of mining, its introduction in fact, by permitting extension of mining into methane rich atmospheres, was followed by an increase in explosions and fatalities. Adams concludes: 'So, can we manage risk better? With each chapter, hopes and expectations become more modest; they are all guessing; if they knew for certain, they would not be dealing with risk. Human behaviour will always be unpredictable because it will always be responsive to human behaviour - including your behaviour.' Conner and Norman (1996) provide, essentially, an extension from this point and focus more specifically on the business of predicting health behaviours. As part of the process, they cover examination of pertinent theoretical models, including the health belief model, health locus of control, and protection motivation theory. Most contributing authors are concerned, like Adams, with the complexities of prediction and influence in this field. 7
NHS National Programme on Forensic Mental Health Research and Development 3. Mental Illness as a Contributor to Violence: the Knowledge 3.1 Is there an association? There is no longer any doubt that there is an association between some mental disorders and violence, but only a modest one. A number of studies, with different samples and focusing on a range of different target behaviours, collectively confirm this for major mental illness as well as for other disorders. Brennan, Grekin and Vanman (2000) applied what is, in effect, a summarising statistical technique - meta-analysis - to the principal community-based epidemiological studies, to test for specific disorder associations with violence as well as the overall perspective of disorder unspecified. Organic and affective psychoses each have some association, but other factors may better account for the relationship than the diagnoses per se. With respect to schizophrenia, effect sizes are significant and large for violence, but significant and small for crime more generally. Subsequently, there has been some suggestion that the US based MacArthur study (e.g. Steadman et al, 1998) may indicate that schizophrenia is a 'protective’ factor when considering violence in the context of mental disorder. In fact, this study cannot do that. There was a higher rate of refusal to participate among the prospective subjects with schizophrenia than others (Monahan and Appelbaum, 2000), and, of more importance, the design was of a type criticised by Monahan and Steadman in their 1983 review as yielding only a part of the knowledge needed to generate an accurate picture of associations. (In this case it provides a true rate of violence only in a treated sample.) The only study not included in Brennan’s review to draw on a complete community cohort, regardless of placement at the time of study and using all possible sources of information, has confirmed just three diagnoses as having a relationship with violence after controlling for the co-occurrence of other disorders - schizophrenia spectrum disorder, alcohol dependence and cannabis dependence (Arseneault et al, 2000). 3.2 Where disorders have a statistical association, what is the nature of the relationship? There is a growing understanding of factors which may correlate with violence in the context of mental illness, but findings are not so consistently endorsed. Some studies have emphasised the importance of fixed antecedents other than mental illness, and therefore unchangeable factors (e.g. Monahan and Appelbaum, 2000). Meanwhile, others have demonstrated the significance of clinical factors (e.g. Taylor, 1985; Taylor et al, 1998; Link and Stueve, 1994). The threat / control-override symptoms association with violence recognised by Link and Stueve has been replicated in large US (Swanson et al 1996) and Israeli (Link, Stueve and Phelan, 1998) community samples, although not in the managed care patient samples of the MacArthur Risk Study (Appelbaum, Robbins and Monahan, 2000). It seems likely that the differences can be accounted for at least in part by real differences in subgroups studied, for example in seriousness of violence (Taylor, 1985), differences in illness antecedents (e.g. Taylor et al, 1998), or the similar implications of separate subgroups with different age of onset of offending (Hodgins, 8
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