Tuesday, 17 January 2012

The Stigma of Mental Illness: The Myth of the Homicidal ‘Schizophrenic’ pt 2/2

Part 1 is here 
Blog summarising the comments is here

The Misconception: Schizophrenia sufferers are ‘violent homicidal maniacs’.

The Truth:  The vast majority of schizophrenia sufferers are not violent or murderous. In fact, the schizophrenia ‘population’ in the UK is just as likely to commit homicide as the general population of the USA and slightly less likely than the general population of Russia.

The implications: People with schizophrenia (and other mental disorders) are discriminated against by society based on a stigma which is wildly inaccurate. This leads to a lower quality of life and further reductions in mental health.

Art By John Cadigan
So what’s the truth behind the homicidal 'Schizophrenic' stigma?
The percentage of the population of schizophrenia patients in the UK who committed homicide in 2007 was about 0.0049%. This is a tiny fraction. Already we can see the vast majority of sufferers are not murders. But how does this compare with the rates of the general population in the UK for homicide? The percentage of the general population who committed homicide in 2007 was about 0.00146%.

If you compare the two, schizophrenia patients are over three times more likely than the general population to commit homicide – which sounds high. It isn’t. This is the relative risk and when you are using such small proportions, it isn’t very useful. This becomes clearer if you view the raw numbers (natural frequencies) for 2007:

For every 200,000 Schizophrenia patients about 10 of them will commit homicide.
For every 200,000 of the general population about 3 of them will commit homicide.

In other words, because the number of homicides is relatively very small, a threefold increase on this, still produces a small number!

The problem with 'relative risk'
This concept of ‘relative risk increase’ is a slippery one. It is beautifully misleading and exploited by the tabloids on a regular basis. Let’s say some research is conducted that finds 1 in 1,000,000 children who eat slowly go on to get bowel cancer and 2 in 1,000,000 children who eat quickly go on to get bowel cancer. Expressed like this in natural frequencies, we can see that this is pretty unimportant – the numbers are so small they are negligible. 

But expressed as relative risk things look a lot different (cue the Daily Mail headline) “Children who eat fast ‘twice as likely to get bowel cancer’, experts say”. Brilliant. This looks a lot more interesting. There is a 100% increase in bowel cancer rates in children who eat quickly compared to those who take their time and suddenly every child in the country is being made to munch in slow motion. You can see examples of this kind of mischievery in the tabloids at Ben Goldacre’s Bad Science blog.

The point is you could have the same relative risk with two very different implications. If the same research had found 1 in 5 children who ate slow got bowel cancer and 2 in 5 who ate quickly got bowel cancer, the relative risk would be the same – twice as likely. In the latter, this is much more important since an increase from 1 in 5 to 2 in 5 involves many more people than in an increase in 1 in 1,000,000 to 2 in 1,000,000.

If this were a tabloid... 
A different way of considering things is to compare the percentage of UK schizophrenia sufferers who committed homicides with that of the percentage of homicides committed by the general population of other countries. And here it gets interesting. 

Who has the greatest proportion of murderers; the general American population or the UK community of Schizophrenia patients? 

It’s the same (if not slightly greater in the US).  The general American population, as with the UK schizophrenia population , is over 3 times more likely to commit homicide than the general population of the UK in and 3.5 times less likely to commit homicide than the general Russian population. In other words you would be just as likely to be murdered by the American who lives next door, as by the man with schizophrenia opposite and 3.5 times more likely be murdered by the Russian chap who lives down the road.

Hopefully this demonstrates the distortion that can occur when using relative risk. The point is not that Russians are more likely than UK schizophrenia patients to commit murder, or that schizophrenia patients are more likely to commit murder than the average UK citizen, because the proportions are too small to be particularly useful. 

The point is that the stats don’t support the stigma; UK Schizophrenia patients are no more murderous homicidal maniacs than the Americans or the Russians.

Statistics, Calculations and References

All data used for year 2007 as this was the most up to date on schizophrenia homicide rates.

Prevalence of Schizophrenia is about 1%

Total population of UK in 2007 was about 60,975,000

No. of homicides by schizophrenia patients in UK in 2007 = 30 http://www.medicine.manchester.ac.uk/mentalhealth/research/suicide/prevention/nci/inquiryannualreports/Annual_Report_July_2011.pdf

% of homicides committed by gen pop in UK in 2007 = 0.00146%
% of homicides committed by gen pop in USA in 2007 = 0.0056%
% of homicides committed by gen pop of Russia in 2007 = 0.018%

Therefore % of UK schizophrenia population to commit homicide in 2007 =
30 / (0.01 x 60,975,000) x 100 = 0.0049 %

(taken from bio) - An emerging artist whose work integrates mystical themes with ancient symbology.  The National Endowment for the Arts recognized Cadigan’s talent in 2001 and helped underwrite his autobiographical documentary, People Say I’m Crazy, which aired on HBO/Cinemax in 2004 after winning over a dozen festival awards. He also has Schizophrenia.


  1. It's now well established by many scientific studies that people with a diagnosis of schizophrenia have a higher incidence of being involved with serious violence, including many homicides.

    Very many of the subsequent homicide inquiries show that the perpetrators have often had inadequate care and treatment by mental health professionals in the run up to the incident, which often would have prevented it.

    Your statistical analysis completely ignores the fact that that these are terrible tragedies, not only for the families of the victims, but also for the perpetrators themselves who face long periods of incarceration.

    Many of these killings are truly horrific and often involve very vulnerable people, including very young children. (There are very many cases in Manchester - see Jael Mullings and Aisling Murray for just two).

    I think the best way to counter the stigma is to acknowledge and counter the violence - rather than pretend it doesn't exist.

    How about a post on decent, timely and effective services for people with serious mental illness which might just help prevent some of the violence and save somebody's life.

  2. Hi Hundredfamilies

    Thanks for your comment. As you will see from the blog I agree that people with psychosis have a higher incidence of being involved with serious violence - over three times more likely. But the absolute risk of a psychosis sufferer committing homicide is very very small indeed.

    My point was that the stigma associated with psychosis is an unfair one. That is the vast MAJORITY (not all but most) of people with psychosis are not violent or homicidal. In fact as i note in the blog the stigma is even more bizarre when you consider the average American is just as likely to commit homicide as a UK schizophrenia patient. this reflects the fact that homicides committed by Schizophrenia patients rise and fall with the population they are in (although consistently slightly higher).

    See Matthew large et al 2009 The relationship between the rate of homicide by those with schizophrenia and the overall homicide rate: A systematic review and meta-analysis

    "Your statistical analysis completely ignores the fact that that these are terrible tragedies..."

    I am not sure how a statistical analysis could include an emotive issue such as this? I would however genuinely appreciate your view on how I've done the stats however and I would be keen to be the first to point out there are differing results. The paper I referenced above found about 6% of the homicides they looked at were committed by schizophrenia patients. If we assume prevalence of about 1% this means schizophrenia patients are 6 times more likely. BUT I am not disputing schizophrenia sufferers are slightly more violent. The point is this is relative risk and that because the proportion of population to commit homicides is so small you need to view the absolute risk which is still very small for schizophrenia sufferers.

    Lastly, I am deeply empathetic to families, victims and schizophrenia sufferers but I don't think the blog implied I wasn't?

    1. There is so much wrong with this analysis, this thinking and your use of data sources I don't even know where to being. Suffice to say, I'm utterly unconvinced.

      It's not just about prevalence, it's about predictability, potential interventions and the 30 odd year history of inappropriate 'diversion' from justice which stacks in the decks in favour of future events like homicide by patients.

      No amount of comparing patients as victims begings to address the very genuine and realistic public concern about unpredited, but predictable violence by mental health patients. If education researches ignored the risk factors which predict truancy in the way that most mental health researchers ignore the relevant backgrounds which predict violent offender, especially stranger attacks.

      And don't get me started on the way NCHIS count things. It's like none of the numeracy I did at primary school. Two dead people means two homicides, not one; homicide followed by suicide is still homicide.

      Want to overcome stigma? Then please don't tell me what to think - make a better argument for WHY.

    2. You can begin why explaining the analysis is wrong. I am a student and I'm perfectly happy to admit to any mistakes I have made as I still have plenty to learn. If I've fudged the stats I'll gladly correct them. That's the only way science makes any progress by being critiqued and improved. I can't do this unless you outline what it is exactly that is wrong.

      But your response doesn't explain why it's wrong. What you and Hundredfamilies seem to be talking about is the mental health system's inability to control and predict violence in mentally ill patients but the blog doesn't discuss this issues (I think it's an important idea though and something I'd like to look into and write about) but it isn't relevant to whether the data analysis is correct or not and whether people with mental disorders deserve the stigma they have.

      Further, you talk about bad stats but the hundredfamilies' website states

      "Killings by people with mental health problems have been increasing steadily in Britain over the last six years for which figures are available."

      Yet if they had bothered to read the new report they would have seen this...

      "We previously reported a rise in homicides
      by people with symptoms of mental illness
      and symptoms of psychosis in England and
      Wales.6 However, for England, data from 2004
      onwards suggested that these increases have
      reversed for those of abnormal mental state at
      the time of the homicide"

      The report is available here http://www.medicine.manchester.ac.uk/mentalhealth/research/suicide/prevention/nci/inquiryannualreports/Annual_Report_July_2011.pdf

  3. Well said Hundred Families and its cold comfort I know, but there are still more mentally ill people who take their own lives first. Until all this glossy research and data (without "historical relevance" aka OLD!)translates to ward, community and training....we will continue to have unwell people left to deteriorate until the brains chemicals no longer have any clear rational.

    The "ripple effect" on families and loved ones, whether death via suicide or homicide, is a tragedy almost too hard to bear. Ineffective, whitewashed investigations add to the agony of the untold story as families are left reeling and bearing the pain of an "untold story".We are told Investigations are carried out using Health Service Guidelines HSG(94)27 to be precise, yet these HSGs are inaccessible if CPA incomplete and there are no suicide indicators to audit which would spot a trend or a cluster........these were withdrawn in 2009 and have not been reinstated!

    Early Intervention Services are highlighted as necessary for those at risk of serious Mental Illness yet how many MH services have these fully implemeted. How many CPAs are not issued and how many times are National Priorities for successful suicide aka "Young male with a violent self harm history" (however short!) left unaddressed by commissioning services out to save ££££ not lives!

    Yes lets counter the stigma and ask why we are failing to treat our mentally ill with care and compassion. Why are we allowing their brains chemicals to deteriorate to the point where there is a risk to public of extreme violence? Would we expect a person with a broken leg to walk? Then why expect a person with a broken brain to think clearly? Yet we treat the former but leave the latter WHY?

    Give us professional and effective mental health services and learn lessons from truly independent investigations. Update research into effective psychiatric medicines and minimize the risk of people self medicating with alcohol and /or drugs ....which may make matters even worse!

    1. Thanks for your comment, particularly on the role of what MH services can do to ensure the safety of patients and the public.

      "Why are we allowing their brains chemicals to deteriorate to the point where there is a risk to public of extreme violence?"

      I'd take several issues with this...
      1) conceptualising mental illness in terms of 'brain chemicals' is on dodgy ground both philosophically and scientifically. There is very little evidence in support of the 'chemical imbalance' hypothesis though many argue in favour of it. There's not really many findings of an actual chemical imbalance, rather the evidence is indirect from the success of antipsychotics which reduce dopamine by blocking receptors. But it doesn't necessarily follow high dopamine causes psychosis. Aspirin treats a headache but headaches aren't caused by a lack of aspirin. (see Richard Bentall - madness explained). The bottom line is the aetiology of mental illnesses is still unknown.

      2)Who is allowing the disorder to get worse? Patients are treated with a range of medications and psychotherapy. If you are criticising the system fine, I agree there may well be problems. But mental health workers aren't systematically and deliberately failing their patients. You speak as if there is a cure for mental illness...

      3)As the blog pointed out there is not 'a risk to the public of extreme violence'. There is a risk to the public in certain specific cases of psychosis and other mental illness and the mental health services NEED to be able to respond to this - it is essential a agree (And I am going to look into the current practice and ways it must improve thanks to your comment) BUT the absolute risk of schizophrenia patients in general committing homicide is absolutely tiny, wouldn't you agree? Your chances of being killed by a general UK citizen is (roughly) 0.00146% and your chances of being killed by a UK schizophrenia sufferer = 0.0049% (AND THIS CONTROLS FOR THE FACT THERE ARE MUCH SMALLER NUMBERS OF SCHIZOPHRENIA PATIENTS IN THE POPULATION). When you consider that the prevalence of schizophrenia is 1% and 0.0049% of these patients will commit homicide the absolute chance of being murdered by a schizophrenia sufferer is 4.9x10^-5% !

  4. I too have several issues still unresolved: Clearly you have insider knowledge and can quote endless stats, but I, as an outsider, have no access to these. All my research has been from personal experience and access via published documents acquired under the Freedom of Information Act (but as we know even Andrew Lansley as Secretary of State for health appears to ignore FOIA.)

    PERSONAL EXPERIENCE: Its almost 7 years that I have been exploring NHS Complaints system, since the avoidable death of my son who was 'found' (how do you find someone you are watching?)in August 2005 (whilst in the Duty of Care of the States agents...so the blurb reads)fatally wounded whilst detained under Section 2 "for his own safety".

    My 29 yr old son was unknown to MH services and presented (according to risk factors identified in Mental health services) in the Nationally recognized highest risk group for successful suicide being "Young, Male with a violent self harm history" ....however short! Yet when he sought help he was sent away with a leaflet!..and when eventually detained under Section 2 was subjected to most of risk triggers robust policy had already identified. So yes, my son and family were failed by Mental Health workers and his brians functions were allowed to deteriorate.It appears he was suffering from unresolved grief (a major risk factor!) following the early death of his father from cancer and my 'almost' demise from a misdiagnosed serious illness. I'm afraid I may be able to challenge many of the perceptions and the stats....and am happy to refer you to anything which will help improve services.

    1. Continue<<<<
      NATIONAL CONCERNS: I am aware that MH services have for too long been seen as "the Cinderella Service of NHS" and during times of austerity it is difficult to justify additional funding BUT so much £££ is wasted on "ineffective investigations" (often carried out by expensive management consultants)Overly generous salaries of too many
      "INTERIM" staff and endless "Inquiries" which lead nowhere because any recommendations made are purely optional and unenforceable! NHS staff are often asked to sign gagging clauses by trusts (this can be evidenced) and if they decide to Whistleblow it seems they are not supported by management at any level...so Boards are often left completely in the dark about real level of failure in their organizations.

    2. Continue<<< I BELIEVE ALL SUICIDE INDICATORS WERE reluctantly WITHDRAWN IN 2009 and have not been reinstated.It seems current data has "historical relevance" aka OLD?
      I wonder how suicide trends and clusters can be identified without suicide indicator to audit?

      WHY WE REMAIN CONCERNED: The then regulator the Healthcare Commission upheld our complaint and offered to "take it outside the NHS Complaints system" We refused and challenged the NHS to resolve our complaint within the system it has in place for everyone. As we said in 2007 WHY? Did HCC know there would be no resolution via NHS Complaints?

      I have yet to be convinced that:
      1. We have effective mental health services.
      2. we have a working complaints system.
      3. We have a viable appeals service via the Health Service Ombudsman.
      And for me Joined Up Thinking tells me if a patient dies and its avoidable there must be failure at some level and if failed then there is nowhere to go!
      There are no really "Independent" inquiries/reviews/investigations and if Care and Treatment inquiries are carried out then maybe the title belies the actual level of Care and Treatment. There appears to be no mention of FAILURE in these inquiries...all FAILURES are referred to as "Service delivery issues"...which are NOT aligned to NICE guidance or local policy! Therefore it appears LESSONS ARE NEVER LEARNED! Continued>>>>

  5. Continued<<<I accept there will always be a mixture of success and failure in every system....but whilst "mental health workers aren't deliberately and systematically failing their patients" ...did I actually say they were? I believe my reference is to the adequacy of commissioning of services as per national /NICE /MHA guidance.
    My comments on schizophrenia are based on myriad of research documents that tell me sufferers from serious mental illness are more likely to turn violence inwards on self rather than violence to others. Sadly this is not always so(and sadly this can be evidenced too).
    I agree with Hundred families as I believe until NHS can prove effectiveness, all the stats, percentages and refs to ethnic origin, are meaningless to families left with the agony of the "untold story inside"

    I gave evidence to the Health Select Committee for their Complaints and Litigation Inquiry and in their findings they agree "NHS complaints system not working say MPs" so I suggested a possible solution to an ineffective Complaints system ...and have yet to hear any comment on it.I believe if system is serious about Patient and Public Safety this will be considered.

    In case it helps here it is:
    I have presented this #1-6 to the Health Select Committee when I gave evidence and have heard no more. Complaints need to be independent of NHS.

    I now believe SMART(er) #7 must be employed across all services for a less fragmented approach. …see below:

    Possible solution to ineffective NHS Complaints service

    1.All complaints on avoidable deaths, across all services , must be ‘truly’ independently investigated.

    2.Building on Advocacy experience, Independent Complaints Advocacy Service (ICAS) could oversee the complaints process…if totally independent of NHS

    3.Funding would come from a COMPLAINTS POOL funded by all Trusts.

    4 Trusts who failed to resolve the complaint at local level aka LOCAL RESOLUTION must pay substantially more into the pool. This would have the added benefit of saving money (as we would no longer need the ineffective PHSO process. Local resolution would mean not escalating complaints to the PHSO.

    5. In fact the £34m that the PHSO service currently costs the tax payer annually, may not be needed as the PHSO service only investigates less than 1.5% of complaints, has never investigated a reconsidered complaint, despite keeping it in
    RECONSIDERATION for up to a year.

    6. All investigation reports must be aligned to show where service failures have not adhered to National Service Framework, local and national policy and NICE guidance.

    7. Ideally across all services, SMART(er) targets replace random fundamentally flawed ones:
    • Specific (what is it?)
    • Measurable (what is needed?)
    • Achievable (Can this be done?)
    • Realistic (What is the learning from this?)
    • Timebound (By when, what timeframe?)
    Only then (Evaluate and Review) for continuous improvement.

    Thank you for your comments but personal experience does not agree.

    1. @Anon

      Thanks very much for finding the time to comment and in such detail. As a medical student hoping to specialise in psychiatry, I am very much interested in the mental health service and you have rightly drawn attention to the very important issue of how to deal with 'at risk' patients. My knowledge is lacking in this area and i appreciate your help. The whole point of starting this blog was to generate discussions and new insights.

      I can't help feeling we are arguing past each other though. The blog was discussing whether there was evidence to support the stigma that schizophrenia patients are 'homicidal maniacs' as often portrayed as the media. I feel I have shown there is not since the vast vast majority do not commit homicide (over 99.9%). Would you disagree with this bit?

      What the blog didn't deal with and what you have very kindly pointed out is how the psychiatric services deal with the minority of patients who are 'at risk' to the public or themselves. And I fully appreciate the significance of what 'at risk' means (violence, self harm, suicide and homicide). I couldn't agree more that in these situations everything possible needs to be done to ensure there is suitable system in place to deal with with these patients ensuring their safety and the public's. And you have pointed out there are some serious failings.

      BUT would you not agree that these are still very much the minority of patients? As such schizophrenia patients and other mentally ill sufferers are not in general a risk to the public. Otherwise, is it not analogous to saying x amount of men commit homicide, and for this minority the families suffer greatly, therefore men are homicidal and a threat to the public.

      Do you see my point? I think there's the issue of the minority who are a public risk which i agree with you on. and there is the issue of whether mentally ill patients are IN GENERAL a public risk in which the answer is no.

      If hundredfamilies stats are correct and 100 homicides take place every year by mentally ill patients thats 100 mentally ill people committing homicide out of how many millions of people who suffer with a mental disorder. This is why i argue the stigma is unfair and is a myth.

      What do you think?

  6. I also agree with many of the comments, but think they miss the point of the original blog post. The point, as I saw it, was that when you are dealing with very very small numbers "group X is 3 times as dangerous as average people" does not equate to "group X is dangerous" -- when the numbers are numbers are small enough, group X might still not be very dangerous at all.

    Now, I'm not familiar with the stigma that schizophrenics are homicidal, but I think the evidence presented seems to indicate if you were developing a nation wide task force to stop homicide, then "dealing with schizophrenics" would be pretty low on your list of priorities.

    At least in the US, traditionally, one of the major moral challenges is balancing the desire to 'help people and/or protect those around a person' and the desire to 'not restrict people who are not actually a danger'. This can be a very difficult balancing act, because it creates tragedy on either side when there are errors. It is tragic when an unrestrained person does something dramatic, like homicide or suicide, it is also tragic when someone who would not commit one of those acts is institutionalized against their will for long periods of time. Sometimes there are straightforward failures of the system, other times it is hard to tell.

  7. Thanks for you input Eric (apologies for calling you Charles in my last comment!)

    Yes this sums up exactly what I was trying to say in the blog post thank you. I think a much more interesting factor is alcohol and other drugs. One review I looked over said "A half or more of offenders are intoxicated by a psychoactive substance at the time of the homicide, with alcohol the most commonly reported substance"


    Although this does not imply causality necessarily, it is just one possible example of other much more significant factors. It does however bring up the whole argument of whether drug/alcoholism is a mental disorder and to what extent addictions contributed to the figure...

    Interestingly, HundredFamilies pointed out that there has been a rise in mentally ill homicides in Britain between 1997-2006 tho There has been been a decrease in the final two years of data collection. This study showed drug and alcohol use correlated with the increase in mentally ill homicides but emphasises it doesn't mean there is necessarily a causal relationship.


  8. General perception is Various brain problems can lead to Various mental disorders. but there is no any evidence to clarify almost all mental disorders are caused by brain problems. there is a spiritual side to it as well so I heard that Para psychiatrists can cure mental disorders better than main stream drugs & psychiatrists. so anyone what do u think?