Suicide pacts and the internet

The recent deaths of nine people in Japan, in October 2004, apparently in two suicide pacts¹—seven suicides in one pact and two in the other—have brought the relatively rare phenomenon of suicide pacts into the limelight. What is unusual is that these pacts seem to have been arranged between strangers who met over the internet and planned the tragedy via special suicide websites. This is in contrast to traditional suicide pacts, in which the victims are people with close relationships.

A suicide pact is an agreement between two or more people to commit suicide together at a given place and time. In England and Wales, for epidemiological purposes, people who have committed suicide within three days of each other in the same registration subdistrict are considered potential victims of a suicide pact.² A related phenomenon is homicide-suicide, in which a person commits a murder and then ends his or her own life. Dyadic death is a term that encompasses both suicide pacts and homicide-suicides.³ A suicide cluster is a group of suicides that occur closer together in time and space than would normally be expected in a given community, with suicides occurring later in the cluster being motivated by earlier suicides. In mass suicide, several people commit suicide usually influenced by charismatic leadership, strong loyalties, or religious beliefs.

Two major epidemiological studies on suicide pacts have been carried out in England and Wales, 36 years apart.²,⁴ The second study showed that the incidence of suicide pacts had declined by 27% in that period.² On average, one suicide pact occurs every month. Suicide pacts almost always involve people well known to each other, mostly spouses, most of them childless. Most of the victims belong to social classes I, II, and III, and a noteworthy proportion work in professions allied to medicine. The methods used are generally less violent; poisoning by exhaust fumes from a vehicle is the most common. But where access to violent means is easier, such as firearms in the United States, suicide pacts entail more violent methods.⁵ Most victims leave jointly signed suicide notes.

Although, by definition, both victims make a joint decision to die in a suicide pact, studies of survivors of pacts have shown that this is not always the case.⁶ In cases where the decision was not mutual, the deceased member is likely to have been the instigator, male, depressed, and to have had a history of self harm, whereas the survivor is likely to be the coerced, female, not mentally ill, and with no previous history of self harm.

Suicide pacts account for less than 1% of the total number of suicides.²,⁴ Both members typically employ the same method. Occasionally, the partners may both use multiple methods to ensure death.⁷ About half have psychiatric disorders and a third have physical illnesses.⁸ In an international comparison of suicide pacts, pacts between spouses were found to predominate in the United States and England, between lovers in Japan, and between friends in India.⁹ The relationship between victims of suicide pacts is typically exclusive, isolated from others, and the immediate trigger for the pact is usually a threat to the continuation of the relationship, for example, impending death of one member from an untreatable physical illness.¹⁰

Suicide pacts have been associated with a rare psychiatric disorder called folie à deux.¹¹ In this condition, two people share the same or similar delusional beliefs. The relationship among people with this psychotic disorder is also usually enmeshed and isolated from the rest of society. Just as in some suicide pacts where one person instigates the plan, in folie à deux the delusion is characteristically imposed by the dominant member of the relationship on to the other person. While suicide pacts are usually seen between spouses, folie à deux is commoner among sisters, usually spinsters.

The potential negative role of the internet in relation to suicides has been highlighted previously.¹² An increasing number of websites graphically describe suicide methods, including details of doses of medication that would be fatal in overdose. Such websites can perhaps trigger suicidal behaviour in predisposed individuals, particularly adolescents.¹³ Cybersuicide refers to suicides or suicide attempts influenced by the internet. Scientific literature on cybersuicide mainly pertains to solitary suicides, and little information exists about the internet and suicide pacts.

The recent suicide pacts in Japan might just be isolated events in a country that has even previously been shown to have the highest rate of suicide pacts.⁹ Alternatively, they might herald a new disturbing trend in suicide pacts, with more such incidents, involving strangers meeting over the internet, becoming increasingly common. If the latter is the case then the epidemiology of suicide pacts is likely to change, with more young people living on their own, who may have otherwise committed suicide alone, joining with like minded suicidal persons to die together.

General practitioners and psychiatrists should continue to remain vigilant against the small but not insignificant risk of suicide pacts, especially while encountering middle aged depressed men who have dependent submissive partners. While assessing risk, one may specifically ask whether a depressed patient uses the internet to obtain information about suicide.