Every few months, the same question about attention deficit hyperactivity disorder (ADHD) is posed in the media - is it real? The latest example comes from leading American neuroscientist, Dr Bruce Perry, who claims ADHD is better thought of as a description than a disease.
I have been conducting research into ADHD for almost 20 years and statements like these have been around for all that time. We're still asking if ADHD is real because science is yet to establish an agreed physiological test for it.
That's why this is an important question for researchers to keep asking. And it's also important for parents because there's a range of causes for hyperactive behaviour other than ADHD, and these should be checked out first.
Other questions really worth asking are why hyperactivity is such a problem today and why it was not so in the past.
Until recently, when social scientists considered ADHD, they explored it as an example of the "medicalisation" of society. In this view, where once a child might have been seen as a ratbag, increasingly kids are seen as disordered (and given drugs).
This approach leads to questions about whether children are now being quelled chemically so they can fit in modern schools and workplaces. These are important, if not entirely new, questions.
In a recently published paper, I identified another growing trend within the social sciences to associate ADHD with crime.
This paper cites a number of US studies that have identified a link between ADHD, school exclusion and delinquency, while a previous review of 48 studies found strong connections between ADHD diagnostic measures, crime and delinquent behaviour.
Within Europe, studies have linked ADHD to juvenile delinquency and criminal behaviour, while other studies indicate higher rates of ADHD among youth offenders, offenders generally and prison populations.
In Australia, the national guidelines on ADHD point to research that indicates a consistent association between ADHD, delinquency, criminal behaviour and recidivism.
That there may be some association between ADHD and criminality is an important insight. But there are reasons for exercising caution in accepting these findings on face value.
First, the descriptors that are the basis for ADHD diagnosis span across hyperactive, inattentive and combined subtypes. This results in a vast array of possible combinations of behaviour that can be diagnosed as ADHD.
To put it another way, ADHD is such a diverse category that it's nearly impossible to identify aspects of it that might be linked to crime.
Second, in these studies, the research categories and definitions of ADHD rarely align. The focus of the studies vary between hyperactivity, inattention or attention deficit, and most of them consider adults.
In other words, we don't know how many of these studies are looking at the same population group, how many would fit the clinical definition of ADHD, and which label came first - ADHD or criminal.
Third, it's important to stress that the occurrence of inattention doesn't make a child delinquent and the presence of hyperactivity doesn't turn a them into a criminal. The majority of society is united in its opposition of major crimes (such as murder), although less convinced about the seriousness of others (such as shoplifting).
The research so far has located offenders with ADHD at the lower end of that scale.
If more of these young people are becoming involved in crime as they get older, it's not because something within their bodies is driving them to do it, it's because, as a society, we have encouraged the conditions for it.
It may be more important to explore what sets a young person down the path toward crime in the first place.
A sociological view?
It's long been recognised that repeated negative labelling and stigmatisation by social institutions can result in careers of delinquency and deviance.
Why would you hesitate to strike back against a system when you have lost faith that it has anything to offer you? Why would you respect the rules of a society that has alienated you since you were young?
The reality is that any path from ADHD to criminality is a long one, with many events and opportunities along the way. What may only appear to be one reaction by a friend's parent, or an assumption by a teacher has a cumulative effect.
Labels such as hyperactive or ADHD tell us more about the people attaching the labels than those receiving them. It's this insight about ADHD that's worthy of far more exploration.
Brenton Prosser is a Senior Research Fellow in Policy, Sociology and Public Health at University of Canberra. He does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.