The Relationship Between Screen Time and ADHD: Reading the Latest Research. A Study from the University of Fukui

"How long are you going to keep playing games!"

"Put that tablet away now!"

I have lost count of how many times
I myself
have said those words at home.

During my time as a teacher,
I also heard
"I'm worried because my child is always playing games"
in parent-teacher conferences
many times.

The impact of screen time on children is
for parents,
and for those involved in education,
a theme that remains a constant concern.

Amidst this,
I recently read a paper that caught my attention.

It is a study by a research group at the University of Fukui
dealing with the relationship between screen time, ADHD symptoms,
and brain structure.

Today,
I will write about
its content and
what I felt after reading the paper.

What kind of study is it?

It is a study published in 2025
in the academic journal "Translational Psychiatry."

The authors are
Qiulu Shou, Masatoshi Yamashita, and Yoshifumi Mizuno
from the Research Center for Child Mental Development at the University of Fukui.

They use data from
a large-scale longitudinal study conducted in the United States
called the ABCD Study.

They analyzed data
covering over 10,000 children at the age of 9 to 10,
including follow-up data from two years later.

What is being addressed is

Screen time (time spent watching videos or gaming),
ADHD symptoms (measured by a questionnaire called CBCL),
Brain structure (cortical thickness and volume measured by MRI)

the relationship between these three.

What was discovered?

I will write the conclusions of the paper
as accurately as possible.

First.
Children with longer screen time
showed a tendency for
slightly stronger ADHD symptoms.

Second.
Even in the two-year follow-up,
children who had longer screen time at the initial point
showed a tendency for increased ADHD symptoms.

Three.
Screen time was
associated with the structure of several brain regions and
their development.

Specifically,
a trend toward smaller cortical thickness development
was observed in the temporal pole and parts of the frontal lobe.

Four.
The results from the baseline data showed that
smaller total cortical volume
partially mediated the relationship between
screen time and ADHD symptoms.

In other words,

Longer screen time
→ Smaller cortical volume
→ More likely to exhibit ADHD symptoms

The existence of this pathway
was supported by the data,
that is.

However,
regarding the relationship where
changes in brain structure mediate
changes in ADHD symptoms two years later,
this analysis
did not yield significant results.

What you must not misunderstand here

This is where
I want to emphasize the most.

First,
this study did not demonstrate a causal relationship.

Even within the paper,
it is clearly stated that
“causality could not be established.”

This is not a study that can definitively say
screen time hinders brain development.

The opposite possibility,
that is, that children with ADHD tendencies
are more drawn to screens,
is also a valid interpretation.

And,
the paper itself points out
that the effect size is small.

Although a statistically significant association was found,
its magnitude is limited,
and clinical implications
must be interpreted with caution.

This is also written in the paper.

In other words,
interpreting this as “reducing screen time will cure ADHD” or
“screens destroy the brain”
goes far beyond
the scope of this paper.

This is as far as my interpretation goes

After reading the paper,
the message I received
is this.

There is some kind of statistical association between
screen time,
the manifestation of ADHD symptoms,
and the development of brain structure.

However,
the correlation is not strong, and
it is unclear what is the cause and what is the effect.
That is all.

That is all there is to it.

No further meaning
is written
in the data.

How to take this as a parent

I will write honestly.

After reading this paper,
I did not think
that I would start drastically limiting my son's screen time
from tomorrow.
I did not think so.

There are three reasons.

First.
The effect size is small, and
I could not interpret it as meaning that reducing screen time
would dramatically change ADHD symptoms.

Second.
I feel at home that
screen time also serves as
a gateway to relaxation and interests
for my son.

Third.
Even so,
I do not think
it is fine to leave it completely unchecked.

Neither "total ban" nor "unlimited"
can be derived
from this paper.

"Discuss it as a family,
and think about a comfortable distance"

I have returned to
this obvious conclusion.

This is, of course,
my personal take.

What I thought when I was a teacher

When I was a teacher,
among the children whose parents complained, "They only play games!",
there were many children
who did not know how to enjoy anything other than games
at home.

It is easy to advise parents to reduce screen time, but
what to fill the freed-up time with
is the real problem.

I have seen several families
where, as a result of taking away games,
the children had nothing to do,
and family conflicts
increased.

If you simplify it by saying "screens are bad,"
you can sometimes
complicate the family relationship itself.

This is a scene
I have witnessed several times in the field.

The importance of being informed

Finally,
there is one thing I would like to convey.

Even if there is research like this,
it is not the "absolute truth."

Being informed
simply provides you with
material to use
when making decisions.

There is some kind of correlation.
But the causality is unknown.
The effects may also be limited.

Within that ambiguity,
each family
must make decisions
that suit their own children.

Telling them to "stop playing games"
or "letting them do as they please"
are probably
neither the correct answer.

Observe your child closely,
talk as a family,
and make small adjustments as you go.

I believe that
this kind of hands-on,
diligent approach
is ultimately all that remains.

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