Among low income adults, poor mental health leads to unhealthy behaviours, such as smoking and binge drinking, rather than the other way around, a new study suggests.

US scientists looked at the relationship between mental health and unhealthy behaviours in terms of socioeconomic status. They wanted to determine whether mental health problems lead to unhealthy behaviours or these behaviours lead to mental health problems.

Almost five hundred adults were interviewed at the beginning of the study. They were then re-interviewed after three, six, nine and 12 months. Levels of stress, anxiety and depression were measured and the scientists also looked at health behaviours, such as exercise, sleep patterns and substance use, including illegal drugs and alcohol.

The study found that unhealthy behaviours were common among adults on low incomes. These included substance use, poor diet and unprotected sex. People on low incomes also had more symptoms of stress, depression and anxiety compared to those earning more.

However, the scientists found that when income was taken into account, the mental health problems of those on lower incomes predicted the level of unhealthy behaviours later on.

Unhealthy behaviours, on the other hand, did not predict mental health issues later on.

The scientists said that one reason for this could be that people with depression and anxiety use substances such as alcohol and illegal drugs to cope.

They believe that focusing on mental health may improve health behaviours overall.

"Clinicians and practitioners should recognise that there may be high rates of depression, anxiety and stress, as well as health-compromising behaviors, in low income populations, and they should assess mental health as well as these behaviors.

"Referring patients for mental health counselling or stress reduction techniques may help to improve their health behaviours," they said.

Details of these findings are published in the journal, Translational Behavioral Medicine.

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