ADHD in teenagers may be triggered by exposure to a group of common chemicals used in applications from food packaging and drugs to cosmetics and fragrances.
US experts found associations between attention-deficit/hyperactivity disorder-related behaviour and endocrine-disrupting chemicals, especially phthalates.
Phthalates are typically added to plastics to improve their flexibility, transparency, durability and longevity.
According to the team, the problematic chemicals act like artificial hormones — with phthalates in particular interfering with the normal activity of androgens.
These ‘male’ hormones — which include testosterone and are found in all humans, albeit in different amounts — play a role in both male traits and reproduction.
ADHD in teenagers may be triggered by exposure to a group of common chemicals used in applications from food packaging and drugs to cosmetics such as shampoos, pictured
‘Endocrine-disrupting chemicals are used in a wide variety of consumer products resulting in ubiquitous exposure,’ paper author and epidemiologist Jessica Shoaff of the Harvard Medical School and colleagues wrote in their paper.
‘The study findings suggest that exposure to some of these chemicals, particularly certain phthalates, during adolescence may be associated with behaviours characteristic of ADHD.’
‘The identification of modifiable risk factors for ADHD is of great public health importance,’ they continued.
In their study, Dr Shoaff and colleagues measured the chemicals found in urine samples taken from 205 adolescents.
They compared this analysis with the result of behavioural surveys undertaken both by each teenager, as well as their parents and their teachers.
From this, the team identified which of the young participants had ‘significant behavioural problems’ — with 40 per cent meeting this criteria and 19 per cent a diagnosis of attention-deficit/hyperactivity disorder.
‘Each 2-fold increase in the sum of antiandrogenic phthalate concentrations was associated with a 1.34 increase in the risk of significant ADHD-related behaviour problems,’ the researchers said.
The associations, the team added, ‘tended to be stronger in male participants.’
The full findings of the study were published in the journal JAMA Network Open.
ABOUT ATTENTION-DEFICIT / HYPERACTIVITY DISORDER
Attention Deficit Hyperactivity Disorder (ADHD) is a behavioural condition defined by inattentiveness, hyperactivity and impulsiveness.
It affects around five per cent of children in the US. Some 3.6 per cent of boys and 0.85 per cent of girls suffer in the UK.
Symptoms typically appear at an early age and become more noticeable as a child grows. These can also include:
- Constant fidgeting
- Poor concentration
- Excessive movement or talking
- Acting without thinking
- Little or no sense of danger
- Careless mistakes
- Difficulty organising tasks
- Inability to listen or carry out instructions
Most cases are diagnosed between six and 12 years old. Adults can also suffer, but there is less research into this.
ADHD’s exact cause is unclear but is thought to involve genetic mutations that affect a person’s brain function and structure.
Premature babies and those with epilepsy or brain damage are more at risk.
ADHD is also linked to anxiety, depression, insomnia, Tourette’s and epilepsy.
There is no cure.
A combination of medication and therapy is usually recommended to relieve symptoms and make day-to-day life easier.
Source: NHS Choices