Diagnosis of ADHD in girls is still being overlooked, and the consequences are significant, research across Wales reveals.

New large-scale research shows that girls are not only less likely to be diagnosed with ADHD in childhood, they are typically diagnosed years later than boys, often in their teens or early twenties. By that point, the impact has already taken hold across mental health, education and wider life outcomes.

The study, based on a Welsh population cohort of over 590,000 individuals, found that young women diagnosed later, between the ages of 12 and 25, experienced markedly worse outcomes than those diagnosed earlier, and significantly worse outcomes than females without ADHD.

One of the most important findings is that these girls were not symptom-free in childhood. Even those diagnosed later showed clear evidence of earlier struggles, including mental health challenges and difficulties at school, when compared with their peers.

This reflects what clinicians see every day. ADHD in girls often does not look like ADHD as it is traditionally understood. It is less visible, less disruptive and far easier to miss.

Rather than externalised behaviour, it tends to present as:

Dr Mukesh Kripalani, Consultant Psychiatrist at The ADHD Centre, said: “ADHD in girls is often not picked up because they don’t fit the stereotype, which is usually focused on how boys present. They are not the ones causing problems in the classroom or playground. They are the ones who are trying very hard to hold everything together, often at a significant personal cost.”

By adolescence and early adulthood, the picture changes. The same study found that females diagnosed later had higher use of healthcare services, poorer mental health, lower educational attainment and more challenging socioeconomic outcomes.

In clinical practice, this often presents as anxiety, depression, chronic stress and burnout, layered on top of years of feeling out of step but not understanding why.

Dr Kripalani added: “By the time many women come to us, they are exhausted. They have spent years trying to manage something they don’t have a name for. A diagnosis can be a huge relief, but it also comes with a sense of what might have been different if it had been recognised earlier.”

The disparity is not accidental. ADHD has historically been defined through a male lens, with diagnostic criteria and awareness shaped around more visible, hyperactive presentations.

Girls are less likely to be referred for assessment, more likely to internalise their difficulties, and more likely to be labelled as anxious, sensitive or simply not coping well.

The result is a consistent pattern of late diagnosis, and a group of young women who are disproportionately affected as a result.

There has been a noticeable rise in adult women seeking ADHD assessments, many of whom describe the same experience of high functioning on the outside, paired with internal overwhelm and eventual burnout.

While this shift in awareness is important, it does not address the underlying issue.