The risk was raised even at lower levels of distress that would not usually come to the attention of mental health services, say the authors. Approximately a quarter of the general population suffer from these minor symptoms of anxiety and depression.
Previous studies investigating the association between psychological distress and mortality have been small and unable to reliably measure thresholds of risk.
In a study partially funded by the Wellcome Trust, a team of researchers from University College London and the University of Edinburgh analysed data from over 68,000 adults aged 35 years and over who took part in the Health Survey for England from 1994 to 2004. Their aim was to measure the role of psychological distress as a risk factor for death from all causes, cardiovascular disease, cancer and external causes occurring over an 8 year period.
Psychological distress was measured using a recognised scale ranging from no symptoms to severe symptoms of stress and anxiety. Death certificates were used to record cause of death.
Dr Tom Russ, the lead author, said "We found that psychological distress was a risk factor for death from all causes, cardiovascular disease, and external causes—the greater the distress, the higher the risk. However, even people with low distress scores were at an increased risk of death. Currently these people—a quarter of the adult population—are unlikely to come to the attention of mental health services due to these symptoms and may not be receiving treatment."
Dr David Batty, the senior author, commented "These associations also remained after taking into account other factors such as weight, exercise, smoking, alcohol consumption and diabetes. Therefore this increased mortality is not simply the result of people with higher levels of psychological distress smoking or drinking more, or taking less exercise."
The study is the largest so far to show a dose-response relation between psychological distress and mortality and has potentially important implications for treatment, say the authors.
Dr Russ concluded "The fact that an increased risk of mortality was evident, even at low levels of psychological distress, should prompt research into whether treatment of these very common, minor symptoms can modify this increased risk of death."
An accompanying editorial says these findings add to evidence that suggests a causal association between psychological distress and cardiovascular disease, but it is not clear how to intervene.