The short answer is that the vast majority of people who suffer from schizophrenia pose absolutely no danger to anyone. However, as we all know from reading the papers, the very few who do harm people get huge amounts of publicity. So why do people with schizophrenia sometimes harm others (or indeed themselves)?
Very often people with this condition, when they are untreated for whatever reason, live in a delusional world where they perceive lots of threats to themselves and their loved ones from conspiracies which simply do not exist. As you can imagine if you were being conspired against, you would feel very scared and sometimes when people are scared they hide away from the outside world. In fact this is what many people with schizophrenia do – but these people rarely make the headlines.
Some people who felt scared of something or who felt that they were being unfairly treated in some way would complain to the authorities – they would ring up the council or complain to the police. Again this is what many people who suffer from schizophrenia do – but one rarely reads about them in the papers either.
But what if you were walking down the street and someone tried to harm yourself or your child. Again maybe you would run, but perhaps you might ‘strike back’. This, sadly, is the sort of scenario one reads about in the paper – the trouble though, in the case of someone who suffers from schizophrenia, is that the threat to themselves or their nearest and dearest is not real but a symptom of their illness. However, to them it is as if it is real. In the worst cases we read about the fear can be so overwhelming – or the need to get rid of the danger so great and immediate – that on very rare occasions greater violence or even a killing can take place.
Sometimes it is not possible to understand, even after the event, what causes the person to react in this way and occasionally, even with good treatment and follow-up, people can act in ways that they gave no clue to before. Furthermore, since one in a hundred people develop an episode of schizophrenia at some point in their lives, for a small number of people the incident where they attack someone will be the first inkling anyone has that anything is wrong.
Of course one has to put the incidence of these unfortunate events into context. If you are the victim of an assault, a mugging or an armed robbery you may not derive much consolation from the fact that the attack was based on a certain amount of logic as opposed to a disease of the mind. Sadly such events also occur in our society, and with much greater frequency.
But all the above refers to the danger to others. There are also dangers to the sufferer themselves which are all too real. Again they are not common, but self harm and even suicide can occur in the course of this illness. Sometimes people realise how ill they are and some suicides are the consequence of this insight. Other episodes of self harm may be due to delusions – for example trying to remove an evil influence which is perceived to be within the sufferer’s own body.
In summary then, there is nothing about schizophrenia that actually makes people violent but because paranoia is a feature of the illness a very small number of sufferers when they feel under attack or threatened might erroneously attack an innocent person.