No, Using Your Phone Won't Cause ADHD

A study ignores the differences between causation and correlation
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TIME reports that teens who are constantly on their phones may be at risk of ADHD. But their headline ignores the differences between causation and correlation. Blink and you miss it, but at the start of the second paragraph, the TIME article admits the research “could not prove causation”. And this is everything.

With cause and effect, one action directly causes another. Without this, they are merely two things that appear to happen at the same time. Like murder and ice cream. Murder rates in the US rise at the same as ice cream sales. Does ice cream cause people to commit murder? No, the relationship between the two is a statistical coincidence – more likely to be based on both increasing in good weather (but even this can’t be scientifically proven).

Go and have a look at the research published in JAMA that TIME is referring to, and you’ll see the findings are simply an “association” between ADHD and phone use. So what does association mean?

Well, it could be purely coincidental – as with homicides and frozen desserts. Or it could mean that increased phone use leads teens to exhibit symptoms similar to ADHD but not to the level that would result in a diagnosis. Or it could mean those who have undiagnosed ADHD spend more time on their phones than others – the ADHD driving the phone usage, not the other way round.

And this lack of causation is something TIME discusses, but only after its hyperbolic headline has done the damage. And what it doesn’t cover is that it could all mean absolutely nothing.

The study asked those taking part to “self-report” any increase in symptoms. Self-reporting is known to produce confirmation bias in its subjects. If you are told an activity might make you less attentive, you look specifically for that inattentiveness. And if you’re looking, you’re more likely to find it – even if it’s not there.

Also, the subjects were teenagers. They’re at an age known to be susceptible to peer pressure. If they believe they are meant to experience an increase in such symptoms, they might report them even if they don’t. Or it may be eagerness to please. They think that’s what the researchers want to hear, so they report it to make them happy.

So what does the research paper itself say?

It finds a “modest association between higher frequency of digital media use and subsequent symptoms of ADHD”. But most importantly, it states that “further research is needed to determine whether this association is causal”.

Until further research is carried out and causation is found between digital media usage and ADHD, it’s safe to say using your phone is as likely to give you ADHD as it is to give you cancer.