The five risk factors for depression – Sarah Berry.

Dr Joanna Dipnall comes from a region in Victoria, Australia 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.

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.”


Your mental health involves your whole body and starts with diet.

Before September 2005, Scott Gooding was a competitive athlete who could run 10 kilometres in under 33 minutes (i.e. really fast).

Then he ruptured disks in his lower back and, after a lifetime of sport and being known to friends and family as “the fit guy”, exercise was off the cards.

“It got so bad that I couldn’t do one push-up or one squat,” says Gooding, now 41. “I was in constant pain and discomfort.”

Apart from the physical pain and the mental struggle with his new identity – “fitness was so much a part of who I was” – he had lost his outlet.

“I couldn’t tap into the therapeutic and meditative effects of running and exercising,” says the former My Kitchen Rules star, personal trainer and health coach. “I dipped in and out of pretty dark periods for the best part of seven years.”

During that time, Gooding began exploring nutrition and how it might help reduce some of the inflamation in his body.

“I think the diet really helped with my back condition and slowly I started to reintroduce exercise,” says Gooding. Moving again helped him shift out of “feeling pretty blue and shit about myself”.

While many individuals intuitively understand the link between how we fuel and move our bodies and how we feel, the medical community is in the midst of a paradigm shift.

“This mind/body dichotomy that has informed psychiatry for at least the last 50 years or so, we know that is erroneous and is not based on evidence because we are increasingly understanding that the whole body is involved in mental health,” says Professor Felice Jacka, head of the Food and Mood Centre at Deakin University.

“Psychiatry is really starting to understand that we need to get back to treating the whole person, not just bits of their brain.”

Jacka, who is also a Black Dog Institute external fellow, is referring to the mounting evidence that our immune system plays a central role in depression and other mental health problems.

“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,” she says.

“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.”

The hippocampus is a “central target” in antidepressant treatment, but Jacka says the impact on its functioning (as well as the immune system and gut health) through diet and exercise helps to explain their pivotal role in influencing mental health.

In fact, she says, in adults and older adults, the size of the hippocampus is linked to the quality of diet.

“Diet and nutrition are as relevant to brain and mental health as they are to physical health. This should be no surprise because nutrition is fundamental to every process of the body and brain,” says Jacka, whose latest study found that improving the diets of those with major depressive disorder had a “substantial beneficial impact” on their mood.

Despite this, Jacka stresses she is not suggesting that diet, or lack of exercise, is the only reason someone might be depressed – or that diet and exercise are the only solutions to depression.

“Depression – and any other mental illness – has many causes and many drivers, but the key thing with diet and exercise is that they’re modifiable,” Jacka says. “So many other risk factors that lead to depression, such as early life trauma, genetics, poverty, disadvantage; these things are very difficult to change.

“If we know that we can change diet and exercise and very quickly, according to the evidence, have an impact on mental health, we believe that this should be a fundamental starting point for treating mental health problems and it can go along with psychotherapy and antidepressant treatments but it should be underpinning all of these treatments.”

This recommendation has been adopted in the updated clinical recommendations for the treatment of mood disorders by the Royal Australian and New Zealand College of Psychiatrists and is significant given that depression is one of the most common reasons people visit their doctor.

“They are now recommending that the first thing that happens when a doctor has a patient with a mood disorder, is to address diet, exercise, smoking cessation and sleep,” Jacka says.

Which is great, except that doctors do not receive any nutritional education during their degrees.

“I attended and spoke at a big conference of psychiatrists on the weekend – psychiatrists and psychologists are still quite astonished to learn that nutrition might be important to mental and brain health,” Jacka says. “They will always say to me: ‘It’s because we never learnt anything about it in our medical degrees.’ ”

Until nutrition training is introduced to medical degrees, Jacka suggests that a quick and easy option is to include dietitian referral services in the Better Access initiative as part of mental health care.

Through the Food and Mood Centre, Jacka and her team are also in the process of developing a nutrition resource that people can use at home.

While Jacka thought getting people to change their diet “would be very difficult” because of the fatigue and reduced tendency to self-care associated with depression, she found the opposite.

“People really, really like this approach because it’s something that’s under their control,” she says. “It doesn’t have to be complicated – you can do a big pot of veggie and legume stew in the crockpot which you can get for $20 from the op-shop – and you can have that for the whole week. You can use frozen vegetables, you can used tinned fish … this idea that it has to be more expensive is not true, the idea that it has to be complicated or time-consuming is not true either.”

Scott Gooding says that he has come to see his “really negative” experience as a positive because it has transformed the way he understands fitness and nutrition and their impact – both physically and mentally.

“The way I see fitness now is simply a tool to improve my mood and make me feel good about myself,” says Gooding, who is also a Blackdog Exercise Your Mood ambassador.

“I also realised you can have this sustained energy and cognitive alertness all day if you’re eating the right food. At no point now is my mood, energy or cognitive function impaired by what I’ve eaten.”


Getting RID of the blues: Formulating a Risk Index for Depression (RID) using structural equation modeling.



While risk factors for depression are increasingly known, there is no widely utilised depression risk index. Our objective was to develop a method for a flexible, modular, Risk Index for Depression using structural equation models of key determinants identified from previous published research that blended machine-learning with traditional statistical techniques.

Demographic, clinical and laboratory variables from the National Health and Nutrition Examination Study (2009-2010, N = 5546) were utilised. Data were split 50:50 into training:validation datasets. Generalised structural equation models, using logistic regression, were developed with a binary outcome depression measure (Patient Health Questionnaire-9 score ⩾ 10) and previously identified determinants of depression: demographics, lifestyle-environs, diet, biomarkers and somatic symptoms. Indicative goodness-of-fit statistics and Areas Under the Receiver Operator Characteristic Curves were calculated and probit regression checked model consistency.

The generalised structural equation model was built from a systematic process. Relative importance of the depression determinants were diet (odds ratio: 4.09; 95% confidence interval: [2.01, 8.35]), lifestyle-environs (odds ratio: 2.15; 95% CI: [1.57, 2.94]), somatic symptoms (odds ratio: 2.10; 95% CI: [1.58, 2.80]), demographics (odds ratio:1.46; 95% CI: [0.72, 2.95]) and biomarkers (odds ratio:1.39; 95% CI: [1.00, 1.93]). The relationships between demographics and lifestyle-environs and depression indicated a potential indirect path via somatic symptoms and biomarkers. The path from diet was direct to depression. The Areas under the Receiver Operator Characteristic Curves were good (logistic:training = 0.850, validation = 0.813; probit:training = 0.849, validation = 0.809).


The novel Risk Index for Depression modular methodology developed has the flexibility to add/remove direct/indirect risk determinants paths to depression using a structural equation model on datasets that take account of a wide range of known risks. Risk Index for Depression shows promise for future clinical use by providing indications of main determinant(s) associated with a patient’s predisposition to depression and has the ability to be translated for the development of risk indices for other affective disorders.


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