Researchers at Oxford University are calling on governments and health and social service programs to put much greater emphasis on treating mental illnesses -- found to more deadly than smoking.

A new study from the university, published through the open-access journal World Psychiatry, indicates about one in in every four people in the United Kingdom annually suffer some kind of mental health problem, whereas an estimated 21 percent of British men and 19 percent of women smoke cigarettes.

The researchers who worked on the study say they referenced 20 papers that had analyzed clinical studies of the risk of death for a wide range of diagnoses -- mental health problems, substance and alcohol abuse, dementia, autistic spectrum disorders, learning disability and childhood behavioral disorders.

Overall, the new data review covered over 1.7 million individual cases and over 250,000 deaths.

The scientific team as well searched for previous studies and reviews that reported the life expectancy and risk of dying by suicide and compared those results to the best data they could find for heavy cigarette smoking.

It was found the life expectancy for people with bipolar disorder is reduced an average nine to 20 years, 10 to 20 years for schizophrenia, between nine and 24 years for drug and alcohol abuse, and around seven to 11 years for recurrent depression.

Meanwhile, the loss of years in heavy smokers is estimated between eight and 10 years.

"We found that many mental health diagnoses are associated with a drop in life expectancy as great as that associated with smoking 20 or more cigarettes a day," Seena Fazel , a doctor with Oxford's Department of Psychiatry, said in a news release. "There are likely to be many reasons for this. High-risk behaviors are common in psychiatric patients, especially drug and alcohol abuse, and they are more likely to die by suicide. The stigma surrounding mental health may mean people aren't treated as well for physical health problems when they do see a doctor."

The market already has many effective drug and psychological treatments for mental health problems, Fazel said. "We can improve mental health and social care provision. That means making sure people have straightforward access to health care," appropriate jobs and meaningful activities in their lives.

"Beyond that, psychiatrists have a particular responsibility as doctors" to make sure the physical health of their patients is not neglected, said Fazel.

"All of this can be changed, he said. "It'll be challenging, but it can be done."