Depression, anxiety and other mental distress may lead to an early death, according to a new study.

Researchers studied the effects of mental health on life expectancy in a large population and found that depression is linked to early death. Also, people who have minor symptoms of depression have an increased risk of dying from heart attacks.

According to researchers, this study offers a causal relationship between "psychological distress and cardiovascular disease."

"These associations also remained after we did our best to take into account other factors such as weight, exercise, smoking, alcohol consumption and diabetes. Therefore this increased mortality is not simply due to people with higher levels of psychological distress having poorer health behaviors," said Dr. David Batty, a Wellcome Trust research fellow in the Department of Epidemiology & Public Health at University College London and senior author on the study.

For the study, researchers analyzed records of 68,000 adults aged 35 years and over. These participants had undertaken a health-based survey between years 1994 and 2004. All the participants' depression levels were measured using a clinically approved test scale.

Researchers analyzed these test results to see if there was any association between severe or moderate depression to the risk of dying within the next eight years.

Almost a quarter of people in the survey had low to moderate levels of depression. Researchers say that these conditions are usually overlooked and not considered as risk factors.

"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 reduce this increased risk of death," Dr Tom Russ, from the University of Edinburgh, said in a news release.

The present study was published in BMJ.