The diagnosis – and misdiagnosis – of ADHD has risen steeply over the last decade. Australia saw a 72.9% rise in the prescription of ADHD medication between 2000 and 2011. Most of these were for mild to moderate ADHD.

In Britain, the rate of medication prescriptions has seen a twofold increase for children and a fourfold increase for adolescents and children.

The sharp increase has in part been attributed to the diagnostic criteria for and ADHD diagnosis being expanded, a response to the concern that the disorder was being underdiagnosed.

‘The kids who don’t get diagnosed or don’t get treatment are at heightened risk for substance abuse, at higher risk for school dropout, for having more car accidents, and having a higher risk of having an interaction with the juvenile justice system,’ explained Harold S. Koplewicz, MD, president of the Child Mind Institute in New York City.

The problem with a broader definition, however, is that it ‘devalues the diagnosis in those with serious problems’, said Dr Rae Thomas, a senior researcher at Australia’s Bond University who published an analysis of the problem in the British Medical Journal.

Like many things, the response to the pendulum swinging too far one way, has sent it swinging too far in the other direction.

Accurate diagnosis of any disorder is necessary to shepherd effective and appropriate treatment, however ADHD has been particularly vulnerable to misdiagnosis because there has been no reliable physiological markers to diagnose disorder.

ADHD diagnosis is based on observed or self-reported behavior in at least two different settings (usually school or home) by different people (generally parents and teachers). Symptoms exist on a spectrum from normal to abnormal and include difficulty sustaining attention, disorganisation, restlessness, distractibility, and a tendency to persistently interrupt.

Whether or not the symptoms are at sufficiently abnormal levels as to warrant a diagnosis is subjective and open to interpretation, or misinterpretation.

With less restrictive criteria and a spike in diagnosis, particularly on the mild to moderate end, the diagnosis of ADHD risks being met with skepticism. This will ultimately compromise those with more severe symptoms who require targeted treatment.

A diagnosis can come loaded with stigma, nudged along by stereotypes, the ill-informed and the judgemental. For example, some teachers have lower academic expectations of children with ADHD. Expectations have a way of creating self-fulfilling prophecies. Children will live up to them – and down to them.

Overdiagnosis of any disorder comes with a financial costs. Medication costs of the misdiagnosis of ADHD have been estimated to be between $320-$500 million in the US.

The medication for ADHD is not without potential side effects, further highlighting the importance of an accurate diagnosis.

In severe cases of ADHD the symptoms are obvious and potential for misdiagnosis is greatly diminished. However, in mind and moderate ADHD, which make up the bulk of all ADHD diagnoses, the measure of symptoms and subsequent diagnosis is subjective and fraught with the potential for misdiagnosis.

Problems with the lack of an accurate diagnostic tool for ADHD have plagued the field, but a recent study may change this.

The Research: What They Did

In a study published in Vision Research, researchers from Tel Aviv University reported that they may have found an objective and physiological way to accurately diagnose ADHD – the presence of involuntary eye movements.

Researchers used an eye-tracking system to monitor the involuntary eye movements of two groups of 22 adults as they completed an ADHD diagnostic computer test.

Each participant did the test twice.

Participants in the first group had all been previously diagnosed with ADHD and were unmedicated when they first took the test. They then repeated the test after they had taken methylphenidate, an ADHD medication.

The second group did not have ADHD.

What They Found

‘We had two objectives going into this research,’ explained researcher Dr. Moshe Fried, who was diagnosed with ADHD as an adult. ‘The first was to provide a new diagnostic tool for ADHD, and the second was to test whether ADHD medication really works – and we found that it does. There was a significant difference between the two groups, and between the two sets of tests taken by ADHD participants un-medicated and later medicated.’

The researchers found that those participants with ADHD were unable to suppress eye movement in the anticipation of visual stimuli when unmedicated.

When these participants took methylphenidate, their involuntary eye movements were suppressed to the same as that of the non-ADHD group, demonstrating the effectiveness of ADHD medication.

 ‘This test is affordable and accessible, rendering it a practical and foolproof tool for medical professionals,’ said Dr. Fried. ‘With other tests, you can slip up, make ‘mistakes’ – intentionally or not. But our test cannot be fooled. Eye movements tracked in this test are involuntary, so they constitute a sound physiological marker of ADHD. Our study also reflected that methylphenidate does work. It is certainly not a placebo, as some have suggested.’

Further trials on larger groups are necessary, but initial results look promising.