The 21st century has seen a dramatic rise in both awareness and understanding of mental health issues and the widespread use of electronic devices like personal computers.

These two factors, according to certain commenters, are inextricably linked – a scourge of the modern era. But how true is this, really?

A new study, published this week in the journal Addiction Biology, attempted to answer that question. Using data from the UK Biobank – the vast biomedical database of genetic information from half a million UK volunteers – researchers from Xi'an Jiaotong University in China used statistical regression models to investigate associations between the use of TV and computers and common mental traits like depression, anxiety, alcohol use, and smoking.

Their conclusion: too much screen time is bad for our mental health. But there are some big caveats to that – so let’s take a proper look at the study before the inevitable tabloid headlines get ahead of us.

“With the increasing use of electronic devices, more attention has been paid to explore the impact of electronic devices on human health,” the authors wrote. “Our study explored the potential association between electronic devices use and mental health using observational and genetic studies.”

Study participants were scored on three behaviors: TV watching, computer usage, and computer gaming. The researchers then used standard statistical techniques to work out the correlation between these variables and the rates of anxiety, depression, smoking, and drinking rates. All variables were self-reported.

The results at this point were mixed. The team had used a few models to measure the associations between electronics usage and outcome variables, differing by the choices of confounding variables taken into account. While most of these models showed some small positive correlation, one in particular – the one which accounted for the most factors – turned up a negative correlation between electronics usage and anxiety scores.

“This is unlikely to be an error – but it is pointing to the patterns of cause and effect being complicated,” commented Kevin McConway, Emeritus Professor of Applied Statistics at the Open University, who was not involved in the study.

That wasn’t the only issue with the investigation so far. As the saying goes, Correlation Is Not Causation, and as McConway pointed out, “if there is an association between media use and a psychological trait, and if we could magically tell that all other relevant factors have been taken into account, we still couldn’t tell whether the different amounts of media use were causing changes in the psychological traits, or the different psychological traits were causing changes in media use.”

That’s why the researchers used what’s known as a Mendelian Randomization approach: a technique that measures the prevalence of certain attributes based on measurable genetic differences. That “effectively gets round the problem,” McConway said, as much of the noise of confounding variables can be filtered out.

“If certain assumptions can be made about the cause and effect relationships involved, that can sometimes allow an inference to be made about what’s causing what,” McConway explained.

In this case, the researchers measured outcomes – the mental traits of anxiety, depression, smoking, and alcohol use – stratified by “genetic variants … related to brain or nerve development, providing a possible way for electronic devices to influence the mechanism of mental traits,” the study explains. Using these statistical results, the team concluded that “electronic devices use was associated with common mental traits and provided new clues for understanding genetic architecture of mental traits.”

“Our work highlights the importance of the electronic devices use for mental health,” the authors wrote. “[It] suggests that short-time electronic devices using might be a new way to reduce the burden of mental health.”

But don’t go throwing all your electronic devices in the trash just yet. There were quite a few important limitations to this study, many of which the authors were well aware of. For example, while the UK Biobank is an invaluable resource in terms of sheer numbers, its participants are highly skewed towards middle-aged or older individuals – hardly representative of the population as a whole.

“In some contexts that may not matter,” McConway said, “but I suspect that it does here, given that the main factors of interest (electronic media use and some psychological traits) have quite strong social aspects.”

More importantly, the study was cross-sectional and observational. In other words, the researchers based their results on a dataset collected by other scientists – scientists who “did not seek to change what the participants would have done anyway,” McConway explained.

“They just measured and recorded what the participants did, or said they did, anyway,” he continued. “So, if using computers a lot is associated in the data with higher levels of depression, we can’t say whether the computer use caused the differences in depression levels.”

It's not difficult to think of situations that fit the bill: perhaps jobs that require sitting in an office on a computer all day are associated with depression, or maybe it’s something to do with the tendency to doomscroll. Perhaps the researchers got the association backward entirely, and being depressed makes a person more likely to spend a lot of time on their computer.

Basically, McConway said, the study “cannot really answer most of the questions that the researchers were interested in” – and for quite a few reasons. Even the team’s use of Mendelian randomization is problematic in this case, he explained, as it relies on the assumption that the genes in question affect a person’s propensity towards mental health issues, but only if catalyzed by certain electronic devices.

“That does seem unlikely to me,” said McConway. “The researchers do report that they did some statistical tests to check this assumption, but I still have doubts on how plausible it is – and if it is not valid, then the mendelian randomizations don’t tell us anything useful about the existence or direction of a cause-and-effect association between the media use and the psychological measures.”

So how worried should we be about our electronic devices turning us all into depressed alcoholics? Probably not too worried – at least not because of this study, says McConway.

“Overall I don’t think that the findings support the suggestion that reducing time spent using electronic devices may help reduce mental health burdens,” he concluded. “That suggestion might or might not be true, but I don’t think that this research can tell us either way.”