A GENERATION ago, parents worried about the effects of television; before that, it was the radio.
Now, the concern is “screen time”, a catchall term for the amount of time that children, especially preteens and teenagers, spend interacting with TVs, computers, smartphones, digital pads and video games. This age group draws particular attention because screen immersion rises sharply during adolescence, and because brain development accelerates then, too, as neural networks are pruned and consolidated in the transition to adulthood.
CBS’ 60 Minutes recently reported on early results from the ABCD Study (for Adolescent Brain Cognitive Development), a US$300 million (RM1.25 billion) project financed by the National Institutes of Health.
The study aims to reveal how brain development is affected by a range of experiences, including substance use, concussions and screen time. As part of an exposé on screen time, 60 Minutes reported that heavy screen use was associated with lower scores on some aptitude tests, and to accelerated “cortical thinning” — a natural process — in some children. But the data is preliminary, and it is unclear whether the effects are lasting or even meaningful.
Does screen addiction change the brain? Yes, but so does every other activity that children engage in: sleep, homework, playing soccer, arguing, growing up in poverty, reading and vaping in secret. The adolescent brain continually changes, or “rewires” itself, in response to daily experience and that adaptation continues into the early to mid-20s.
What scientists want to learn is whether screen time causes measurable differences in adolescent brain structure or function, and whether those differences are meaningful. Do they cause attention deficits, mood problems, or delays in reading or problem-solving ability?
Have any such brain differences been found? Not convincingly. More than 100 scientific reports and surveys have studied screen habits and well-being in young people, looking for emotional and behavioural differences, as well as changes in attitude, such as in body image.
In 2014, scientists from Queen’s University Belfast reviewed 43 of the best designed such studies. The studies found that social networking allows people to broaden their circle of social contacts in ways that could be both good and bad, for instance, by exposing young people to abusive content.
The review’s authors concluded that there was “an absence of robust causal research regarding the impact of social media on the mental well-being of young people”. In short, results have been mixed and sometimes contradictory.
Psychologists have also examined whether playing violent video games is connected to aggressive behaviour. More than 200 such studies have been carried out; some researchers found links, others have not. One challenge in studying this and other aspects of screen time is identifying the direction of causality: Do children who play a lot of violent video games become more aggressive as a result, or were they drawn to such content because they were more aggressive from the start?
Individual variation is the rule in brain development. The size of specific brain regions such as the prefrontal cortex, the rate at which those regions edit and consolidate their networks, and the variations in these parameters from person to person make it very difficult to interpret findings. To address such obstacles, scientists need huge numbers of research subjects and a far better understanding of the brain.
The ongoing ABCD study expects to follow 11,800 children through adolescence, with annual magnetic resonance imaging, to see if changes in the brain are linked to behaviour or health.
The study began in 2013, recruiting 21 academic research centres, and initially focused on the effects of drug and alcohol use on the adolescent brain. Since then, the project has expanded and now includes other targets such as the effects of brain injury, screen time, genetics and an array of “other environmental factors”.
The recently published paper covered by 60 Minutes provided an early glimpse of the anticipated results. A research team, based at the University of California, San Diego, analysed brain scans from more than 4,500 preteens and correlated those with the children’s amount of screen time (as reported by the children themselves in questionnaires) and their scores on language and thinking tests. The findings were a mixed bag.
Some heavy screen users showed cortical thinning at younger ages than expected; but this thinning is part of natural brain maturation, and scientists don’t know what that difference means. Some heavy users scored below the curve on aptitude tests, others performed well.
But the accuracy is hard to ascertain. The association between small differences in brain structure and how people actually behave is even more vague. Clear conclusions are extremely hard to come by, complicated by the fact that a brain scan is no more than a snapshot in time: a year from now, some of the observed relationships could be reversed.
But surely, screen addiction is somehow bad for the brain? It’s probably both bad and good, depending on the individual and his viewing habits. Most parents are probably already aware of the biggest downside of screen time: the extent to which it can displace other childhood experiences, including sleep, climbing over fences, designing elaborate practical jokes and getting into trouble.
Indeed, many parents — maybe most — watched hours of TV a day themselves as youngsters. Their experiences may be more similar to their children’s than they know. --NYT