Adults diagnosed with ADHD are likely to have a ‘milder’ form of the disorder than children, researchers have suggested.
Grown-ups with the condition are ‘less impaired’ by the condition day-to-day, and are no less likely to become professionally successful.
Experts also found those diagnosed after the age of 18 are far less likely to suffer mental and physical health problems linked with ADHD, like bipolar and digestive problems.
They are also less likely to exhibit genetic characteristics that are thought to contribute to a person’s risk of the disorder.
It comes amid record high diagnoses in England, where around 2.5 million people are believed to be living with ADHD – a 20-fold rise over two decades.
The surge is largely being driven by adults, official figures show.
The new study, conducted by a team at the University of Pittsburgh, found those diagnosed later in life were almost twice as likely to have a better education than childhood cases.
People diagnosed with ADHD in adulthood may have a ‘milder’ form of the disorder than children, researchers have said
Attention deficit hyperactivity disorder, or ADHD, has long been linked to poorer school performance because patients find it harder to concentrate and are more forgetful.
Speaking of the findings, the authors conclude that, when diagnosed in adulthood, ADHD may present a ‘milder clinical profile’ compared to those diagnosed as a child.
The scientists, whose findings were published in the journal JAMA Network Open, looked at 13,527 adults who reported having an ADHD diagnosis.
Of these, 3,853 received theirs in childhood, while the remaining 9,674 said they were detected in adulthood.
An estimated 741,000 of the 2.5 million people with ADHD in England are children and young people aged five to 24, data show.
The US team compared both group outcomes on a range of health and lifestyle factors linked to ADHD as adults, beginning with education performance.
They discovered that around 28 per cent of those diagnosed as adults had a university degree, compared to 14.2 per cent of those with ADHD identified during childhood.
They then looked at the average household annual income.
Around 15 per cent of the adult group had a yearly income of $100,000 to $150,000 – £74,000 to £111,000 – compared with 9.4 per cent of those diagnosed as children.
Figures suggest that around 12 to 13 per cent of all American households earn this amount.
Researchers also said the adult diagnosis group were less likely to have eight of nine additional mental health conditions that have been previously linked to ADHD.
The biggest differences were found for post-traumatic stress disorder (PTSD), bipolar disorder and personality disorders.
For every 100 people, the later-diagnosed group had about eight fewer people with PTSD, seven fewer with bipolar disorder and five fewer with personality disorders.
A similar pattern was uncovered for physical conditions associated with the disorder like lung, digestive and musculoskeletal problems.
Furthermore, the adults had a slightly lower ‘ADHD polygenic risk score’ – a measure of how likely their genetics put them at risk of the disorder.
Despite the differences between those identified earlier and later in life, both groups suffered more health problems than people without the condition.
The study comes amid ongoing debate over ADHD in Britain.
A Channel 4 documentary broadcast last month investigated the rise in ADHD diagnoses in the UK and featured sceptical experts.
In promotional material for the show, titled ‘The Great ADHD Myth?’, Dr Iona Heath, ex-president of the Royal College of General Practitioners (RCGP), said: ‘[ADHD]is certainly not a medical condition as far as I’m concerned.’
The documentary sparked backlash from charity ADHD UK, which said: ‘ADHD is not a myth. It is not a social construct.’
The charity also complained to media regulator Ofcom, while the RCGP warned against ‘invalidating the condition’.
Other experts have warned that the rise in adult cases is being driven, in part, by behaviours once considered normal increasingly being over medicalised.
