Dr Joanna Dipnall comes from a region in Victoria where adolescent suicide rates are alarmingly high.
With a background in statistics and epidemiological research, Dipnall wanted to see if she could do something to “help circumvent these tragedies”.
“I felt I could try and make a difference,” says Dipnall, a lecturer in the Department of Statistics, Data Science and Epidemiology at Swinburne University.
Risk indexes are used for cardiovascular disease, diabetes, dementia and even suicide risk for those with bipolar. They help to identify predisposed people so that healthcare professionals can help those individuals take preventative measures.
There is not currently a reliable index for depression, so for her PhD Dipnall developed The Risk Index for Depression (RID), published in the Australian and New Zealand Journal of Psychiatry.
She analysed the data of more than 5500 adults, looking at the association between depression and five previously identified components of depression; demographics, lifestyle, diet, biomarkers and somatic symptoms.
While each of the components heighten the risk of depression either directly or indirectly, “diet came out initially with the highest association”, says Dipnall, whose PhD was a collaboration through Deakin and Swinburne universities.
Specifically, regular consumption of fruit, leafy greens, other vegetables, cooked whole grain and whole grain bread were associated with a reduced risk for depression, while a diet high in processed foods and sugar was associated with a higher risk.
“Previous research I did found bowel symptoms came out as one of the strongest risk factors for depression,” Dipnall says. “Your stool can be an indication and that’s obviously impacted by your diet… [Deakin’s] Food and Mood centre are looking at the issues of dietary fibre and gut health – it all fits in.”
In fact, the recent research of Dipnall’s PhD supervisor, Felice Jacka, of Deakin’s Food and Mood Centre, has been pivotal in exposing the centrality of the link between depression and diet.
“We’re increasingly understanding that the gut and its resident microbiome has a leading role in prompting immune function and is very much involved in brain health,” Jacka told Fairfax.
“We have extensive evidence from animal studies, showing when you manipulate diet, you manipulate the function of the hippocampus, which is a key area of the brain involved in learning and memory, but also in mood regulation.”
After diet, lifestyle factors (things like work status, physical activity, sleep, smoking, sexual activity and drug usage) had the greatest impact, followed by somatic symptoms (things like pain, bowel health, vision, hearing, arthritis as well as respiratory, liver and thyroid function).
Dipnall notes the five components that make up the RID model are a starting point and “on their own are not enough to provide a holistic prediction of depression”. This is because data was not available for other significant risk factors like stressful or traumatic life events.
“The nature of the index is that it is modular, so you can add elements,” she says, adding that she hopes to build on the model in future.
In the meantime, she wants people to understand that depression is not simple. Some of the factors that cause depression are not within our control, but there are some changes we can make to improve our outcomes.
This knowledge has the ability to help some of the 1 million Australians suffering from depression each year. Taking care of diet and exercise, reducing stress and getting good quality sleep are also modifiable factors that can help people to stay well as they are recovering from mental illness.
“It is a multitude of factors and [people] can’t just look in isolation in their lifestyle,” she says.
“This is confirming that there are more elements people need to take into consideration – it’s not just diet, it’s their lifestyle environ and how they deal with their somatic symptoms… My research was looking at what impacts depression with a view to looking at the areas people can modify to reduce that risk.”
If you are experiencing depression or anxiety, support is available by calling beyondblue on 1300 22 4636.