The RID, developed by Swinburne University of Technology lecturer Dr Joanna Dipnall, revealed that an individual is more likely to become depressed if their diet is poor, their lifestyle is erratic and they do not exercise.
Dr Dipnall, who lectures in the Department of Statistics Data Science and Epidemiology, said she developed the RID to help identify the most common risk factors for depression, and to give health professionals an early intervention tool.
The research found that the risk of depression is most closely linked to diet, followed by physiological factors and then lifestyle patterns, such as sleep and exercise.
While diet has long been associated with mental health, Dr Dipnall said more research now needs to be conducted on the role the gut plays in mental health.
She added that a fibre-rich diet is the key to a healthy mind.
"Dietary fibre appears central to gut health, which has recently been a key focus of depression research. Our findings provide further support for diet as a key modifiable factor in gut health, and in depression risk."
Prevention, not cure
Dr Dipnall said future research is being planned to build on the current RID model. Her research, Getting RID of the blues: Formulating a Risk Index for Depression, has been published in the Australian & New Zealand Journal of Psychiatry.
"The RID is about prevention," she said. "It aims to identify individuals with a predisposition to depression, as well as which is the key determinant that would reduce this risk."
"A diet comprised of fibre-rich foods such as leafy green salads, vegetables and whole grains has been consistently associated with a reduced risk for depression," she added.
"At the same time, an unhealthy diet high in processed foods and high-fat dairy has previously been found to be associated with increased odds for depression.
"Lifestyle factors such as problems sleeping, snacking behaviour and exercise activity have all been found to be associated with individuals' mental health."