Schizophrenia and homelessness can be a deadly combination

News that the perpetrator of the tragic mass homicide in Bondi Junction may have had schizophrenia raises the public alarm about the danger of people with severe mental illness in our community. While we can be reassured that the homicide of strangers by people with schizophrenia is extremely rare, homelessness is a known risk factor for loss of continuity of treatment, and for stranger homicide.

Bondi Junction attacker Joel Cauchi was both mentally ill and homeless.

We conducted an international case-controlled study of stranger homicide offenders with psychosis which identified 42 cases from NSW, Ontario, Finland, and the Netherlands in the previous two decades. The rate of stranger homicide by people with psychosis was about one per 14 million population per year, or one in NSW every two years. One in five of the stranger homicide offenders was homeless, compared to none in the comparison group, and only one in eight were receiving treatment with antipsychotic medication.

It is hard enough for people without mental illness who are employed and have good social skills to find suitable accommodation in our major cities. For people with severe mental illness who are rarely able to work and who have impairment in a range of other social domains, finding and keeping stable accommodation is extremely difficult.

It is well known that most of the chronic rough sleepers in our cities have chronic schizophrenia. People experiencing both homelessness and mental illnesses often have trouble accessing treatment. This is due to the nature of their illness and also because mental health services are poorly organised and badly resourced for the treatment of the homeless who are mentally ill.

Stable housing is a fundamental requirement for the continuous treatment of people with chronic forms of schizophrenia. Not having a fixed address means that community services often cannot locate patients to check on their progress, administer treatment, and assist them in other ways.

Not having a place to secure belongings such as vital documents, a phone charger, or a change of clothes, adds to the chaos of patients who are already quite disorganised. In practice, compulsory treatment as a condition of a community treatment order requires an address, and can be avoided by moving, including interstate.

The despair of homelessness adds to the urge to drink and take drugs, even if substance use had contributed to developing mental illness and losing accommodation in the first place. The revolving door between the homeless sector and our prisons also results in loss of both accommodation and continuity of care.

Mass homicides of strangers usually involve automatic weapons and are mainly committed by resentful, isolated men and people with psychotic illnesses such as schizophrenia. Moreover, symptoms of schizophrenia are more common among people who survive mass homicide perpetration when compared to those who died alongside their victims, suggesting a stronger association between mental illness and mass killing.

Thankfully, the phenomenon of mass killing of strangers has become extremely rare in Australia as a result of the improvements in firearm safety after the Port Arthur massacre in 1996. To further improve public safety, we advocate for better continuity of care for people with severe forms of mental illness through the creation of a network of supported housing integrated with mental health care.

Housing people experiencing homelessness while mentally ill is a finite problem. It has been estimated that there are as few as 3000 people with chronic mental illness living in the open in Australia, many of whom revolve between hospitals and prisons, at vast expense to the community, but with very high mortality and poor health outcomes.

Building and managing small-scale communities for the homeless who are mentally ill will not only save money, reduce stress on the public mental health system and improve their health outcomes; it will also reduce the likelihood of further tragic events similar to those in Bondi Junction on Saturday.

Olav Nielssen is a psychiatrist at St Vincent’s Hospital and is a Professor of Psychiatry at Macquarie University, and is the founder of the Habilis Housing, an initiative to provide supported housing for the homeless. Matthew Large is a conjoint professor of psychiatry at UNSW.