There has long been an association between mental illness and dangerousness in the public mind.
It is now clear, however, that the proportion of violent crime attributable to mental illness is extremely low and much is linked to co-occurring drug misuse rather than mental illness itself.
This issue comes into sharp focus in the Irish media whenever there is an apparent case of murder-suicide.
It is difficult to comment on these matters publicly in the immediate aftermath because that can be construed as commenting on the particular case. It is timely, then, when there is no such case in the headlines, to present some facts.
In the US, the rate of murder-suicide is approximately 0.2 to 0.3 murder- suicides per 100,000 population per year. This is significantly higher than in England and Wales, where the rate is 0.04 per 100,000 population per year. The rate in Ireland is more difficult to establish with certainty.
If the US rate applied to Ireland, with our population of 4.7m people (based on the 2016 census), we would expect, at a minimum, 9.5 murder-suicides per year. If the England and Wales rate applied, we would expect 1.9 murder-suicides per year in Ireland.
Last February, the National Suicide Research Foundation (nsrf.ie) reported that there have been at least 23 murder-suicides in Ireland since 2004.
This gives a rate of at least 1.8 murder-suicides per year or approximately 0.04 per 100,000 population per year.
This is similar to the rate in England and Wales, and considerably lower than that in the US.
It is worth noting that the NSRF figure is an ‘at least’ figure, so the true number may be higher. It seems likely, however, that Ireland’s rate of murder-suicide is essentially the same at that of England and Wales.
Can murder-suicide be predicted? Looking across the international literature, it is clear that most perpetrators of murder-suicide are men (88%), most commonly in their mid-40s. The most common life event in the run up to the murder-suicide is the loss of, or a
significant change in, a close personal relationship.
Up to two thirds of perpetrators have a history of mental illness (most commonly depression) but fewer than 12% have had contact with specialist mental health services.
It is unclear how many perpetrators of murder-suicide are truly mentally ill at the time and it is stigmatising to the mentally ill to presume that anyone who perpetrates murder-suicide is mentally ill.
Shocking acts are commonly committed by people who are not mentally ill and some cases of murder-suicide may relate more to domestic violence than to mental illness. In these circumstances, it is possible that targeted interventions and supports relating to domestic violence might help prevent escalation to the point of murder-suicide in certain families.
Unfortunately, as is the case with any event that is as rare as murder-suicide, accurate prediction is impossible at the individual level. Even with the best use of current evidence, the various factors linked with murder-suicide (male, mid-40s, past depression) are so common that it is simply not possible to predict with accuracy if a given individual will engage in murder-suicide.
So, if prediction is impossible, is prevention impossible too? Possibly not. Given that many who engage in murder-suicide have a history of depression, it is possible that treatment of depression might help prevent murder-suicide.
On the one hand, it is certainly not proven that better treatment of depression prevents murder-suicide, but, on the other hand, it is difficult to see how there could ever be such proof, because it is impossible to count events that have been prevented.
In any case, there are already many good reasons for better treatment of depression, including relieving suffering, improving quality of life, and, possibly, reducing risk of self-harm.
In terms of targeted interventions, the NSRF notes that 90% of murder-suicides involving mothers and 60% involving fathers are associated with a desire to alleviate real or imagined suffering in their children.
This suggests that this clinical feature should present particular cause for concern. Again, however, it remains the case that the vast majority of people who express such concern about their children will not engage in murder- suicide.
We do know, however, that there is a need for greater emphasis on child risk assessment and greater involvement of families in mental health care.
Although there is no direct evidence that these measures will prevent murder-suicide, they are important elements of good care for many reasons.
There is also a need for better support for those bereaved by murder-suicide, focused on timely provision of information, practical assistance, and sustained psychological support.
The HSE has produced clear and helpful guidelines on responding to murder-suicides, focused on pro-active response plans in local health areas. The NSRF has provided advice on sensitive and factual reporting.
Overall however, it is important to remember that while various measures discussed above may well reduce the likelihood of murder-suicides in the general population, it remains impossible for either families or health and social care professionals to predict murder-suicide in any given case.
Brendan Kelly is Professor of Psychiatry at Trinity College Dublin and author of Mental Health in Ireland: The Complete Guide for Patients, Families, Health Care Professionals and Everyone Who Wants To Be Well (Liffey Press, 2017).
Useful resources: The Samaritans (www.samaritans.org) provide a listening service to anyone who contacts them (telephone 116 123; email firstname.lastname@example.org). Pieta House (www.pieta.ie) offers support for those who are suicidal and those bereaved (telephone 1800 247 247).