Scientists flag reason why more boys than girls have autism and ADHD

It’s a question that has long stumped researchers. 

Now, new light has been shed on one reason why three times more boys than girls are diagnosed with autism and ADHD. 

Researchers from the University of Rochester have suggested that boys may be more vulnerable to environmental stressors such as toxic ‘forever chemicals’ as their brain develops.

These chemicals are believed to warp brain signals, causing long-term behavioral changes in boys, such as social anxiety, difficulty sitting still and finding it hard to follow instructions. 

Found in everything from plastic bottles, clothing and even drinking water, these chemicals can take thousands of years to degrade and have been linked to cancer, infertility and birth defects.

In the current study, the scientists pinpointed a specific ‘forever chemical’ known as PFHxA, which is used in paper food packaging and stain-resistant fabrics. 

Researchers say it could cause anxiety-like behaviours seen in autism and ADHD, but oddly, mostly in boys.

They conducted a study that involved exposing baby mice to the toxin via their mother’s milk.

The scientists found that the male baby mice showed alarming developmental changes including a decrease in activity levels, increased anxiety and memory problems. 

Significantly, researchers did not observe the same behaviour changes in the female baby mice. 

Even years after the mice had first been exposed to the chemical, they still showed behavioral patterns associated with the disorders, suggesting forever chemical exposure could have long-lasting effects on the brain. 

Professor Elizabeth Plunk, first author of the study and expert in environmental medicine described the findings as ‘concerning’.

Writing in the European Journal of Neuroscience, researchers said: ‘Although these effects were mild, finding behavioral effects only in males was reminiscent of many neurodevelopmental disorders that are male-biased.’ 

‘Understanding the impact of PFHxA on the developing brain is critical when proposing regulations around this chemical,’ Prof Plunk added. 

The researchers hope that this will be the first of many studies investigating the harmful effects of PFHxA on the brain—with a renewed focus on the areas of the brain responsible for movement, memory and emotions. 

The findings come amid rising concerns over a surge in ADHD diagnoses—with an estimated 2.5million people in England now living with the attention deficit disorder, according to the NHS.

ADHD is a neurodevelopmental disorder that affects concentration, impulse control and activity levels.

Common symptoms include restlessness, distractibility, forgetfulness, difficulty following instructions or managing time, and making impulsive decisions.

Similarly, officials have warned that the NHS is ‘overwhelmed’ by soaring autism rates as 200,000 people wait for an assessment in England according to the latest figures. 

Autism is a spectrum disorder which affects how people communicate and interact. 

According to the World Health Organisation, around one in 100 children across the globe have the condition.  

Autistic children may avoid eye contact and not respond to their name being called, among other symptoms.

Autism is not a disease and people have it from the moment they are born, although it may not be spotted until childhood and sometimes much later.

In the past, it has been assumed that autism and ADHD tends to affect more boys than girls and that the disorders are somehow ‘male-biased’. 

But experts have warned that this may be because boys are more likely to be referred and get a diagnosis—because there symptoms tend to be more pronounced—rather than a genetic predisposition.

For example, the NHS notes that autistic girls may hide some signs of autism by copying how other children behave and play.  

But either way, researchers are now worried that forever chemicals could be contributing to the surge in cases, with experts warning earlier this year the the UK’s regulation of the toxic element is too lax. 

PFAS are found in hundreds of everyday products due to their durability. 

But last year a review of 500 studies found they were linked to ‘serious health implications’, including weakening the immune system and being a factor in cancer diagnosis.

Now the Environmental Audit Committee (EAC) is set to put recommendations to the Government by the end of the year on whether the UK needs to introduce stricter guidelines.