Is ADHD a Mental Health Illness?

Research studies generally support attention deficit hyperactivity disorder (ADHD) as a valid mental disorder, but there are also disagreements.

Support for ADHD

ADHD is a common neurodevelopmental disorder in children worldwide. Findings from neurological and genetic studies generally support the argument that ADHD is a valid disorder.

The central psychological deficits in people with ADHD have now been linked to several specific brain regions such as the frontal lobe, its connections to the basal ganglia, and their relationship to the central aspects of the cerebellum.

Most neurological studies find that as a group those with ADHD have less brain electrical activity and show less reactivity to stimulation in one or more of these regions.

For instance, in a study of twins for attention problems (AP), researchers found that, compared to those with low AP, children with high AP showed decreased activation in dorsolateral prefrontal, parietal and temporal brain regions, while there was an increased activation of premotor cortex and regions associated with visual selective attention processing.

And neuro-imaging studies of people with ADHD also demonstrate relatively smaller areas of brain matter and less metabolic activity of this brain matter.

In a 2002 research report, researchers say that their neuro-imaging study found that, compared with age- and gender-matched control subjects, boys with ADHD had smaller absolute frontal lobe volumes. Researchers say their findings suggest that ADHD is associated with decreased frontal lobe gray and white matter volumes.

Research studies also support a genetic basis for ADHD with some key findings:

  • Numerous family‐genetic studies have reported a higher prevalence rate of psychopathology, particularly ADHD, in parents and other relatives of children with ADHD.

  • In twin studies, scientists have found that if one twin has symptoms of ADHD, the risk that the other will have the disorder is as high as 75‐90%.

The Disagreements

There have been arguments that ADHD does not exist or is not a valid medical or psychiatric disorder. The major arguments include there is not a known biological marker or characteristic for ADHD, and ADHD diagnosis is a subjective process.

The inability to conclusively identify causes of ADHD calls into serious question the legitimacy of ADHD as a medical disorder. Unlike other medical conditions which have clear and identifiable markers that indicate the presence of disorder, in the case of ADHD, science has yet to discover a biological marker or characteristic for ADHD.

The subjective nature of the ADHD diagnosis is another cause for criticism. Some researchers argue that ADHD is contested precisely because of the subjective nature of the diagnostic process.

ADHD, like other mental health issues, are diagnosed with tools such as the Diagnostic and Statistical Manual of Mental Disorders by the American Psychiatric Association (APA), or the International Classification of Diseases and Related Health Problems by World Health Organization (WHO). However, there is no one standardized checklist in use for ADHD diagnosis; rather, there are at least two dozen, if not more.

As a result, the ADHD diagnosis is made subjectively by medical professionals through use of behavioral checklists and rating scales. Thus often, whether a person obtains a diagnosis of ADHD can be a matter of degree, the diagnostic tool used, and the medical professional’s personal opinions.


Sources consulted:

Quinn, Michael and Andrea Lynch. “Is ADHD a ‘real’ disorder?” Support for Learning, vol. 31, no. 1, 2016, pp. 59-70.

Barkley, Russell A., et al. “International consensus statement on ADHD.” Clinical Child and Family Psychology Review, vol. 5, no. 2, 2002, pp. 89–111.

Mostofsky, Stewart H. et al. “Smaller prefrontal and premotor volumes in boys with attention-deficit/hyperactivity disorder.” Biological Psychiatry, vol. 52, no. 8, 2002, pp. 785-794.

Tistarelli, Naomi, et al. “The nature and nurture of ADHD and its comorbidities: A narrative review on twin studies.” Neuroscience & Biobehavioral Reviews, vol. 109, 2020, pp. 63-77.


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