People with minor symptoms of mental health problems like anxiety or depression may have a lower life expectancy, a new British study suggests.

Researchers analyzed data from more than 68,000 people in England with an average age of 55 who were surveyed from 1994 to 2004.

About a quarter of people in the study suffered from minor symptoms of anxiety and depression. (iStock)

People who experienced symptoms of anxiety or depression on a standardized scale had a higher risk of death from several causes, including cardiovascular disease, than those without any such symptoms, the researchers found after reviewing the survey data and death certificates.

"These associations also remained after we did our best to take into account other factors such as weight, exercise, smoking, alcohol consumption and diabetes," said Dr. David Batty, study senior author of the department of epidemiology and public health at University College London.

"Therefore this increased mortality is not simply due to people with higher levels of psychological distress having poorer health behaviours," he added in a release.

In this study, about a quarter of people suffered from minor symptoms of anxiety and depression that don't come to the attention of mental health professionals.

The researchers called it the largest study so far to look at the relation between psychological distress and mortality.

Untreated mental illness

Unlike deaths from heart disease, cancer deaths were not associated with low levels of psychological distress in the study.

A drawback of the study included missing data from a relatively large number of participants. Also, the researchers did not have any direct measures of atherosclerosis or hardening of the arteries. Persistent symptoms of depression are associated with atherosclerosis, the study's authors said.

"Trial evidence has not suggested that treating depression decreases mortality in patients with existing cardiovascular disease but evidence from the current study of the increased risk associated with even low levels of psychological distress in the general population suggests that the overall picture may be more complex," they concluded.

The researchers excluded deaths in the first five years of follow-up, which reduces the likelihood of reverse causation — the possibility that early stages of disease such as chest pain might cause psychological distress, a journal editorial noted.

"It is now clear that an association between psychological distress and cardiovascular disease exists well below the threshold that would lead to a diagnosis of depression or anxiety or require specific treatment," Glyn Lewis, a professor of psychiatric epidemiology at the University of Bristol, UK, said in the editorial.

Instead of avoiding stressors, it might be more useful to change our psychological interpretations of stressors with the aim of trying to reduce their biological impact, Lewis suggested.

Cognitive behavioural therapy or talk therapy is meant to help people change how they interpret stressors, but there's no evidence that the treatment works at a population level to help people reduce their perceived stress, he said.

Marjorie Wallace, chief executive of the British mental health charity called SANE, also commented on the research.

"We are glad that there is now growing evidence for the dangers of allowing depression and other mental illnesses to go untreated," Wallace said on the charity's website.

"Even what may be considered mild depression can cut short a person's life, not only through the use of alcohol, cigarettes and other substances, but by directly affecting the recovery from physical illnesses such as heart disease.

"The debilitating effects on a person's life can lead them to neglect themselves and their management of long-term conditions such as diabetes or cancer."