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Having a healthy lifestyle is the most important factor to prevent depression, new research has found.
Cambridge University neuropsychologist Professor Barbara Sahakian and her team used data from the UK biobank to reach conclusions about depression.
The biobank sample included nearly 300,000 people, studied over a nine-year period.
Sahakian told Sunday Morning her team had conducted lifestyle measures at the beginning of the study before anyone was depressed and then followed up on the participants later.
"What we found was that a healthy lifestyle reduced the risk of depression by 57 percent."
She said the research found that a healthy lifestyle featuring seven to eight hours of sleep on a regular basis was one of the key factors in avoiding depression.
"If you can get a good night's sleep, you can wake up and feel very positive about things, like you can get through your work and you're looking forward to seeing your colleagues and you're ready for a nice social life."
She said sleep helps our cognition as we consolidate our memories while we sleep and it also helps to strengthen our immune system.
"During sleep, we remove the toxic waste by-products from the brain."
Another important factor for having a healthy lifestyle is the need for social connections.
"We are social animals and we have a social brain so it is really important that we interact with friends, family and colleagues and that will make us feel much better and it's also great for our cognition."
Sahakian and her team also looked at genetic risk scores.
"What we found is that those with even the lowest genetic risk scores were 25 percent less likely to develop depression.
"So actually, the lifestyle factor of having a healthy lifestyle and reducing it [depression] by 57 percent was a stronger fact."
The study used neuroimaging to see the differences in the brain, changing volumes of areas like the hippocampus, vital for memory and learning, and the amygdala, for emotional regulation.
At last count, in 2016, more than 12 percent of New Zealanders were on antidepressants, 16 percent of females, 9 percent of males, 22 percent of women over age 65.