Patients in Britain are being diagnosed with attention deficit hyperactivity disorder (ADHD) and prescribed powerul drugs after unreliable online assesments, an investigation has found.

An undercover BBC Panorama reporter was diagnosed with ADHD at three private clinics via video calls, but a more detailed, in-person NHS assessment showed he didn't have the condition.

The investigation followed tip-offs from patients about poor and rushed assessments at some private clinics including Harley Psychiatrists, ADHD Direct and ADHD 360, with dozens of whistleblowers spoken to.

The clinics told the BBC they follow national guidelines and conduct thorough assessments.

Despite a surge in the number of adults seeking diagnoses in recent years, in some areas it can take more than five years to secure an NHS assessment fro ADHD, so many patients have turned to private clinics, often costing hundreds of pounds.

NHS consultant psychiatrist Dr Mike Smith told the BBC he was seriously concerned about the number of people who might "potentially have received an incorrect diagnosis and been started on medications inappropriately".

"The scale is massive,” he added.

Living with undiagnosed ADHD as an adult is said to cause unstable relationships, poor work or academic performance, low self-esteem, major mood swings, and other problems.

ADHD UK states that 2.6 million people in the UK are estimated to have ADHD. But what exactly is ADHD, what causes it, and how can adults get diagnosed?

Here’s everything you need to know.

What is ADHD?

ADHD, which stands for attention-deficit hyperactivity disorder, is a condition that affects people’s behaviour.

Its symptoms include restlessness, impulsivity, hyperactivity, and issues with concentration.

Many people experience inattention or changes in energy levels from time to time. However, for a person with ADHD, the inattention, energy levels, and concentration difficulties are major and more frequent, which has the potential to put pressure on their work and home life.

ADHD is widely divided into three types: inattentive/distractable, impulsive/hyperactive, and combined.

There has been a surge in the number of adults seeking ADHD diagnoses in recent years, partly as a result of more awareness being raised about the condition. Support groups say it has long been under-diagnosed, particularly in women.

What causes ADHD?

While the exact cause of ADHD is still unknown, evidence suggests that genetic factors might be at play.

According to Hopkins Medicine, children with ADHD have low levels of the brain chemical dopamine.

Additionally, their brain metabolism in the areas of the brain that control attention, social judgement, and movement seem to be lower.

The NHS believes that being born prematurely, having a low birth weight, and parents consuming alcohol, drugs, or cigarettes during their pregnancy could play a role, as well as genetics and diet.

How can you get diagnosed as an adult?

If you’re an adult that believes you may have ADHD, the NHS suggests that you speak to your GP.

GPs aren’t qualified to formally diagnose you with ADHD, but they can refer you for specialist assessment.

During your GP appointment, they may ask you questions about your symptoms, family history, health conditions, and recent life events.

If they conclude that you have undiagnosed ADHD, have symptoms that can’t be explained by a mental health condition, and/or have symptoms that significantly affect your daily life, they will refer you to a specialist.

Who you’re referred to depends on your symptoms, age, and what’s available in your area. It could be a psychiatrist or another appropriately qualified healthcare professional.

Getting diagnosed as an adult is more difficult because there is some disagreement over which ADHD symptoms are seen in adults vs children with the condition.

Under the current diagnostic guidelines the NHS uses, adults cannot be diagnosed with ADHD unless their symptoms have been present from childhood. This is because medical professionals currently believe that ADHD cannot develop for the first time in adults.

Their symptoms also have to have at least a moderate effect on areas of their life, like their social relationships, romantic partnerships, work or education, and driving habits.

How is ADHD treated?

The condition can be treated using medicine or therapy, but the NHS advises that a combination of the two is often the best treatment plan.

These do not permanently cure ADHD, but they help those with ADHD concentrate better, be less impulsive, and feel calmer.

Another possible treatment that has displayed good results is sticking to a healthy and balanced diet, and keeping a diary of what you eat and drink, and the behaviour that follows to see if there is a link between certain types of food and your symptoms.

You can also discuss taking omega-3 and omega-6 fatty acid supplements with your GP, as there is some evidence suggesting that they may be beneficial for people with ADHD.