Exercise may protect against depression, but this study doesn’t show it

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Children who get enough exercise aren’t just more physically fit, but also have better mental health in adulthood, according to research at the Norwegian University of Science and Technology. (But see our analysis below.)

The study, published in the journal Pediatrics, established a ‘considerable’ link between physical activity and good mental health.

The researchers say the results could help reduce rising rates of depression in young adults. Depression in teenagers aged 15 and 16 has nearly doubled since the 1980s, according to the charity YoungMinds.

They examined just under 800 children when they were six years old, and conducted follow-up examinations with about 700 of them when they were eight and 10 years old. Physical activity was measured with accelerometers, and parents were interviewed about their children’s mental health.

The study’s first author, Tonje Zahl, said: ‘Being active, getting sweaty and roughhousing offer more than just physical health benefits. They also protect against depression.

‘This is important to know, because it may suggest that physical activity can be used to prevent and treat depression already in childhood.’

Instant analysis

This study looks at moderate to vigorous physical activity within the context of childhood depression and whether it can predict or ameliorate major depressive illness in children, suggesting that it could be an alternative to medication or therapy.

It sought to achieve this by observing a community sample of 795 children, aged six, in Trondheim, Norway, with follow-up at eight and 10 years of age.

The children were assessed for movement by the usage of accelerometers, which were supposed to be worn consistently for seven-day periods. Data was only used from those accelerometers that showed more than three days of data, and greater than 480 minutes of activity per day. The study did not elaborate greatly on how this affected the data or to what extent the data was skewed or trimmed as a consequence. The incidence of major depressive disorder within the study was noted as being around 0.3 per cent to 0.4 per cent.

Ultimately the study offered very equivocal results, but suggested that moderate to vigorous physical activity was a predictor for lower levels of major depression within two-year intervals. It could be a chicken versus egg scenario — perhaps more movement occurred as the children were less depressed and vice versa.

There were a few problems with this study. Critically, though, it used a sample number of just 700 to assess an incidence of a very rare issue in children: major depression.

A better focus would have been on children with mood or anxiety issues — milder conditions that would benefit from a range of different management options.

I felt the data was shoehorned into a fairly flimsy conclusion that movement predicted depressive disorder in later years. Considering the numbers involved, that is very presumptuous.

Research score: 1/5

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