Depressive symptoms and objectively measured physical activity and sedentary behaviour throughout adolescence, 2020, Kandola et al

Full title: Depressive symptoms and objectively measured physical activity and sedentary behaviour throughout adolescence: a prospective cohort study

Open access, https://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(20)30034-1/fulltext

Perhaps there are reasons for the increased sedentary behaviour, and identifying them might be useful. Or we could just go with the easy assumption and call it quits...

"Children who sit too much 'more likely to get depressed'"

https://www.bbc.co.uk/news/education-51475399

 

Rich people spend more money than poor people, therefore we can cure poverty by encouraging poor people to spend more money (not actually give them any more, just tell them that it's their fault they are poor coz they don't spend enough)

 

Without context for the sedentary behaviour this seems an assumption .

Teenagers generally are less mobile - there are many reasons why. Without a societal context this seems a half baked study

 

Not impressed, there is no way of telling what is causative. There are many reasons why someone may be active, including liking physical activity, not a universal thing, and having the time to do so. That we have no reliable means of testing for depression means a wide error margin, this unfortunately makes interpretation difficult given too many people's convictions about exercise being itself evidence of less depression, a conviction that is likely wrong.

Yes, as people get older they have more obligations, more school work, have to start working, etc. Some more than others and it's impossible to account for the reasons. Those are the same reasons adults seldom engage in physical activity, they simply don't have the time. As an observation, this is about as naive as being puzzled at why people's height changes during adolescence.

 

At least they realise they need an objective measure for activity:

"Nearly all previous studies have used self-report measures of activity, which are prone to bias, provide unreliable estimates, and do not sufficiently account for sedentary behaviour or light activity, which comprise most of daily waking activity."

 

I would be impressed if somebody actually found the real cause of depression from what I have seen low grade inflammation may be key in understanding why some people are prone to lifelong clinical depression . it would also be really nice if there was some way of measuring what people call depression considering this disease effects so many people who from the outside at least do not seem to have very hard lives a possible clue to the fact that it is not caused by stress or the way people think . edited to add just look at the numbers of professional athletes who end up with depression as a diagnosis I am pretty sure they where very active as teenagers once again asking the wrong questions to justify activity as a cheap cure all damned lazy thinking.

 

Ironically, the RBC study and this study have the same mis-attribution of causality.

RBC variance is a function of physical activity, even in healthy people.

I am not going to hold a student's thesis to a higher standard than a trial published in the Lancet though.

 

Most athletes were never going to get depression in the first place, even if they were completely sedentary. They have young fit parents without depression, some of whom were professional athletes. It really screws up research.

Sam Darnold is an NFL quarterback that got sick with mono pretty late (at 22) during an NFL season and returned to play. His grandpa was Dick Hammer, a former Olympian. His dad played college ball. His mom is a PE teacher.

 

Also note, in the methodology:

Also, the use of incidence rate ratio is strange, given they are not using it as the rate ratio of the incidence of reaching those thresholds on the questionnaires, but simply a point increase in scores.

 

Some people would argue that depression is a metabolic disturbance in the brain. Therefore, it's no wonder it is associated with physical inactivity and alterations in sleep cycle, appetite etc.