What is really going on in the ADHD brain?

A disease expert reveals how knowledge of our biology is the key to understanding and treating symptoms

In the nineties, during my training, I worked in adolescent psychiatry, where you usually see attention deficit hyperactivity disorder (ADHD).It was clear what the right treatment and support could do.It's the difference between passing an exam and being kicked out, having a social network and losing it.

After that, standard practice was to stop treatment at age 18 because ADHD was considered a "childhood disorder."So when I went on to specialize in adult psychiatry at Nightties, I found all the same problems.These people were still using NHS services but were now being treated for other conditions such as anxiety or depression, 'atypical personality disorders' or substance use.

Now we find that the ADHD is miraculously gone at age 18, but we have a lot of work to do.I would not call the increase in numbers an overdiagnosis.These are mostly people who are missed or misdiagnosed.It's estimated that 3 percent of adults have ADHD, so if even a third of them wanted medication, we'd see 1 percent of adults on prescriptions.The current number is much lower than that.

The cause of ADHD is probably about 80 percent genetic.If someone has it, almost always a mother, father or both have it.Another risk factor is premature birth or a very low birth weight.

The brain is complicated.We don't know exactly what causes each symptom, but we have theories.Understanding biology is very important.People with ADHD often have a terrible sense of shame and failure after years of being criticized and making mistakes.Knowing that it's the brain that's different—not a moral failing—and strategizing around them is medicine in itself.

The 'control center' is small

Brain scans, especially during adolescence, have shown that people with ADHD have structural differences in certain areas of the brain.These apparent differences appear to disappear in adulthood, so we believe that ADHD symptoms may be caused by differences in brain development and maturation.