A genetic study of 16,000 teenagers in Norway suggests that vulnerability to heavy screen use may partly be written in our DNA – and overlaps with the genetics of conditions such as attention-deficit/hyperactivity disorder (ADHD) and depression.
Some families are cautious around alcohol or gambling because addiction can run in families. Could something similar be true for excessive screen use – now one of the most common types of behaviour in modern adolescence?
“People often think screen use is purely an environmental factor that we are exposed to. But if genetics plays a role, the picture becomes more complicated. It may also reflect underlying behavioural tendencies shaped by our DNA,” says lead author Evgeniia Frei, a biomedical scientist at the University of Oslo who studies the genetics of mental health.
The idea turns out to have a biological component. New research suggests that how much time teenagers spend on screens may partly reflect how the brain regulates attention, reward and mood.
To investigate this possibility, the researchers conducted a genome-wide association study – a method that scans the DNA of thousands of people for tiny differences – and identified genetic variants associated with screen behaviour.
The findings do not mean that screen time causes mental health conditions, the researchers emphasise. Instead, the results suggest that an underlying biological vulnerability may influence both screen behaviour and the risk of disorders such as ADHD or depression – meaning that screen habits may sometimes reflect deeper differences in how the brain regulates behaviour.
Tracing screen habits from birth to adolescence
Intergenerational trends in screen behaviour remain largely unexplored, partly because only a few generations have had widespread access to digital media. Household televisions only reached Norway in the 1960s, and just 60 years later, “each person below age 80 spends several hours per day on screens,” says co-author Olav Smeland, a psychiatrist at the Oslo University Hospital who researches the genetics behind mental disorders. “We do not know that much about it. At the same time, there is this intriguing link to mental illness among adolescents.”
“Some types of screen behaviour can become addictive,” Evgeniia Frei adds, noting conditions such as gaming disorder and internet addiction. That possibility has prompted researchers to ask a broader question: why are some young people drawn far more strongly to screens than others – even when they grow up in similar environments?
To explore whether screen habits might have a biological component, Evgeniia Frei and co-authors analysed DNA and behavioural data from more than 16,000 teenagers in the long-running Norwegian Mother, Father and Child Cohort Study. They then used complementary genetic analyses to test whether the same pattern held up across different statistical approaches.
From cord blood to teenage screen habits
Researchers collected the children’s DNA from umbilical cord blood at birth in the early 2000s and later compared it with screen habits in adolescence.
When the teenagers were 14, researchers asked them to estimate how much time they spent with screens on a typical weekday, including television, gaming and social media.
This type of self-report is “not ideal,” Evgeniia Frei says, since people often misjudge how they spend their time. “But for now, it is often the best we have.”
Evgeniia Frei and her team also compared the teenagers’ screen habits with medical records from Norway’s national health system to determine whether screen use overlapped with mental disorders – revealing a striking genetic overlap.
A genetic dimmer switch for screen behaviour
The analysis revealed that screen behaviour is partly heritable. “We found that genetics plays some role in how people use screens,” Evgeniia Frei says. Importantly, the signal appeared across two methods for estimating SNP-based heritability, strengthening the case that the finding is not just a statistical fluke.
Like many complex traits, screen behaviour appears to be polygenic – meaning that it is influenced by many genes working together. Instead of a single gene acting like an on-off switch, hundreds or thousands of small genetic differences – SNPs – act like a dimmer switch, collectively nudging behaviour toward more or less screen use.
“Having one or two of these variants does not mean much,” Olav Smeland says. “But as they accumulate, they can influence how people interact with screens.”
Teenagers who reported spending more time on screens tended to carry more of these variants. Each variant has only a tiny effect on its own, but together they can subtly shift behaviour – much like turning the dimmer switch slightly brighter.
Linking screen habits to medical records
In addition to loci – genetic addresses where variants occur – previously linked to screen use, the team identified three new loci specifically associated with social media use. The researchers then checked those signals against data from the UK Biobank, where some showed the same direction of effect, offering tentative support from an independent sample.
When the researchers compared screen behaviour with diagnosed mental health conditions, a clearer picture of the biological connections began to emerge.
The analysis also revealed genetic correlations between screen behaviours and mental disorders – meaning that some of the same genetic patterns that influence mental health also appear to influence screen habits. That overlap also held up in sensitivity analysis that excluded teenagers with psychiatric diagnoses, suggesting that the pattern was not driven only by diagnosed cases.
Genetic liability to ADHD was associated with more time spent gaming, watching television and communicating with friends on social media, while genetic liability to major depressive disorder and alcohol use disorder was associated with more time spent on social media – patterns suggesting that some of the same genetic influences may affect both mental health and screen habits.
What the findings might mean for mental health
At least part of the overlap between screen behaviour and mental conditions likely reflects shared genetic vulnerability rather than a direct causal effect, Olav Smeland says – suggesting that the same brain systems involved in attention, reward and mood may also shape how strongly people respond to digital media.
“The kids who are more disposed to getting ADHD are also the kids who are more disposed to spending more time gaming and on social media.”
The researchers say that it is still too early to pinpoint the biological mechanism, but they suspect that it may involve the brain’s reward systems or how people process signals from the outside world. Additional analyses did not support clear causal relationships, and some links weakened after accounting for educational attainment, suggesting that the genetics connecting screen habits and mental health are complex rather than simple or one-directional.
Understanding this relationship could help clinicians to identify young people who may be more vulnerable to both heavy screen use and mental health problems.
Screen habits as an early signal of vulnerability
Evgeniia Frei says future studies that focus on specific mental health conditions will likely uncover more meaningful patterns. “It might be important to do more granular and more focused studies, even if they will be smaller,” she says.
Taken together, the findings suggest that screen behaviour may offer an early signal of vulnerability, Olav Smeland says – one that may reflect deeper biological differences in attention, reward and mood.
That conclusion rests not on a single result, but on several converging lines of evidence: heritability estimates, overlap with psychiatric genetics, support from sensitivity analyses and tentative validation in an independent cohort.
Mental healthcare providers, he says, should start asking about screen habits during assessments. “We need to start paying attention.”
