Warning signPeople with mental illness are six times more likely to die in an accident than the general population, according to new international research.

Researchers from Lund University in Sweden and Stanford University in California studied some 6.9 million adults aged 20 years or older living in Sweden in 2001. The group was followed up for 8 years, and the number of deaths during this time was identified using the Swedish Death Registry.

During the study period there were 22,419 accidental deaths (0.3%), with the most common causes being from falls, transport accidents and accidental poisoning. While 9.4% people in the study population had a psychiatric diagnosis, among those who died from accidents during the study period, 26% had a psychiatric diagnosis.

Overall, the researchers found a four- to seven-fold increased risk of accidental death among people with personality disorders, six- to seven-fold increased risk among people with dementia, and a two- to four-fold increased risk among people with schizophrenia, bipolar disorder, depression or anxiety disorders.

Having any mental disorder was associated with highly increased risks of death from accidental poisoning (5.5-fold among women and 3.2-fold among men), or falls (4.2-fold among women and 4.5-fold among men), and modestly increased risks of death in transport accidents (1.7-fold among women and 1.3-fold among men). This increased risk remained after controlling for factors such as age, socioeconomic status, and substance use. 

Lead researcher Dr Casey Crump said: “In this large cohort study, people with mental disorders had a highly increased risk of accidental death – which was substantially more common than suicide. Mental disorders overall were associated with a 5.3-fold risk of accidental death among women and a 6.6-fold risk among men.”

Common symptoms could lead to increased risk

The researchers believe several factors may contribute to the increased risk of accidental death among people with mental illness. “Common symptoms of psychiatric illness, such as fatigue, poor concentration and sleep disturbance, may increase the risk of accidents through impaired judgement, co-ordination and reaction time,” Dr Crump added. “Psychiatric medications may also contribute through common side effects, or unintentional overdose resulting from confusion or an effort to relieve symptoms of the underlying disorder. Some mental disorders are also associated with risk-taking or self-destructive behaviour, increasing the risk of accidental death.”

The researchers believe that more attention needs to be given to the risk of accidental death among people with mental illness, and that interventions to help reduce suicide among people with mental illness should also address the common causes of accidental death.

Reference: Crump C, Sundquist K, Winkleby MA and Sundquist J. Mental disorders and risk of accidental death. British Journal of Psychiatry, bjp.bp.112.123992, ePub ahead of print, 22 August 2013