Attention-deficit hyperactivity disorder (ADHD) drugs alter the structure of children’s brains, scientists have discovered as they warn doctors against issuing prescriptions unless strictly necessary.
Scans of children with ADHD taking methylphenidate, best known as Ritalin, showed significant changes in the distribution of white matter, which is important for learning and coordinating communication between regions of the brain.
The difference between these children and other ADHD sufferers given a placebo was apparent after just four months.
A similar trial on adults showed no white matter changes between the methylphenidate and placebo participants, suggesting the brain is vulnerable to structural change while developing.
The study’s authors warned that the long-term consequences of Ritalin on the brain are unknown, saying the medication should only be given to children who are significantly affected by ADHD.
In 2017-18 75,000 children between the ages of six and 17 in England received a prescription for ADHD medication, according to the NHS.
This amounts to just over 1.5 per cent of boys and roughly 0.35 per cent of all girls of those ages.
The study also follows growing concern in recent years that university students – whose brains are still developing – are illegally acquiring the prescription-only drugs to improve their concentration.
Liesbeth Reneman, from the University of Amsterdam, said: “What our data already underscore is that the use of ADHD medications in children must be carefully considered until more is known about the long-term consequences of prescribing methylphenidate at a young age,”
Published in the journal Radiology, the study involved 50 boys aged 10 to 12, and 48 adult men aged 23 to 40.
None had ever taken methylphenidate before, making this the first trial to proactively study potential changes in brain development due to the drug as they took place.
MRI scans before and after the four-month period showed differences in the left hemisphere of the brain, including roughly a doubling of fractional anisotropy, which reflects aspects of white matter such as nerve fiber density, size and myelination – the process of coating nerve fibers.
Many ADHD patients are on ritalin and other medications for years, despite their being little knowledge about its long-term effect on the brain.
Dr Punit Shah, a lecturer in psychology at the University of Bath, cautioned that brain structure is not always related to behaviour, and that doctors of ADHD patients should remain focused on this,
But he added: “I agree with the authors’ sentiments about the (over)prescribing of medication for ADHD and related neurodevelopmental conditions.
“This is a bigger issue in the US than the UK, but there is growing use of the pharmacological agents in children and young adults across the world.
“Indeed, ADHD medications are also inappropriately being used by university students, whose brains are also still developing, to boost their academic performance.”
Earlier this month said children of older mothers and fathers are less likely to realise if their child has ADHD.
University of Surrey researchers found the larger the age gap between children and their parents, the older children are when given a diagnosis.
Recent years has also seen a growth in concern that children who spend a lot of time on smartphones are more likely to develop the condition.