How is ADHD diagnosed?
There is no hard science involved - just vague descriptions of unwanted behaviours
Many people mistakenly believe ADHD is diagnosed using a series of scientific tests. In reality 'no biological marker is diagnostic for ADHD' and the behavioral criteria listed below are the basis for a diagnosis. Every claim about ADHD should be viewed in light of these criteria.
ADHD diagnostic criteria in the Diagnostic and Statistical Manual of Mental Disorders 5th Ed.
To qualify for a diagnosis of ADHD a child (aged under 17) should display either six of the Inattention and/or six of the Hyperactive/Impulsive behavioural criteria listed below:
often fails to give close attention to details or makes careless mistakes in schoolwork, work, or during other activities
often has difficulty sustaining attention in tasks or play activities
often does not seem to listen when spoken to directly
often does not follow through on instructions and fails to finish schoolwork, chores, or duties in the workplace
often has difficulty organizing tasks and activities
often avoids, dislikes or is reluctant to engage in tasks that require sustained mental effort (such as schoolwork or homework)
often loses things necessary for tasks or activities (e.g., toys, school assignments, pencils, books, or tools)
is often easily distracted by extraneous stimuli
is often forgetful in daily activities
Hyperactivity and Impulsivity
often fidgets with hands or feet or squirms in seat
often leaves seat in classroom or in other situations in which remaining seated is expected
often runs about or climbs excessively in situations in which it is inappropriate
often unable to play or engage in leisure activities quietly
is often “on the go” or often acts as if “driven by a motor”
often talks excessively
often blurts out answers before questions have been completed
often has difficulty awaiting turn
often interrupts or intrudes on others (e.g., butts into conversations or games)
Note: Those aged 17 and over only need to display five of either the Inattention or Hyperactive/Impulsive behaviours and DSM5 also recognizes two additional categories of ADHD where children “do not meet the full criteria for ADHD”.
Commentary - It is absurd that normal childhood behaviours like fidgeting, disliking homework, playing loudly, climbing and talking excessively, are regarded as evidence of a childhood psychiatric disorder.
Clinicians don't even need to observe ADHD type behaviours. They diagnose children or adolescents with ADHD by relying on third party reports of children exhibiting the above behaviours. Usually parents and teachers are asked to complete a questionnaire detailing if their child always, often, sometimes or never displays these behaviours.
How ‘often’ a child or adolescent ‘fidgets’ or ‘interrupts’ or ‘avoids homework’ or ‘fails to remain seated’ or is ‘distracted’ so that they exhibit ‘some impairment’ is not defined in DSM5. Except for those aged 17 and over being required to display less criteria (five instead of six), the diagnostic criteria are identical for pre-schoolers and adults.
Research indicates that, in the majority of cases, teachers are the first to suggest a student be referred for diagnosis. Many of the diagnostic criteria, in particular "making careless mistakes, not seeming to listen, failing to finish school work, being disorganised, disliking schoolwork or homework, blurting out answers and leaving a seat when remaining seated is expected", are all evidence of a student’s failure to thrive or comply in a school environment. Bad teachers can cause these ADHD type behaviours and then be the first to suggest a child has ADHD (and then provide the evidence used to diagnose it). However, a diagnosis of ADHD shifts the focus away from what might be wrong with the teacher or the school and assumes the child's biochemistry is the problem.
Teacher attitude and practice is just one of many non-biological factors that have been shown to effect rates of ADHD diagnosis and medication use.
Variations in both parent and clinician attitudes and practice have a strong impact on a child’s chances of being diagnosed and ‘medicated’ (or 'drugged' depending on your perspective). Arguably a diagnosis of ADHD says more about the adults in a child’s life (parents, teachers and doctors) than it does about the child.
Many other factors including gender (with boys 3x more likely to be diagnosed as girls), ethnicity of students and teachers, divorce, low maternal education, lone parenthood and the receipt of social welfare, sexual abuse, sleep deprivation, perinatal issues, artificial food additives, mobile phone use, postcode and regulatory capture (drug company influence), have all been associated with an increased risk of an ADHD diagnosis.
Despite this, and the absence of any supporting evidence, it is widely assumed that a child with ADHD has a neurodevelopmental disorder caused by faulty brain chemistry and function.
 American Psychiatric Association (2013), Diagnostic and Statistical Manual of Mental Disorders. Fifth Edition, (DSM-5) pp. 59-66
 Russell G, Ford T, Rosenberg R, Kelly S. The association of attention deficit hyperactivity disorder with socioeconomic disadvantage: alternative explanations and evidence. J Child Psychol Psychiatry. 2014;55(5):436-45.
 Weinstein D, Staffelbach D, Biaggio M. Attention-deficit hyperactivity disorder and posttraumatic stress disorder: differential diagnosis in childhood sexual abuse. Clin Psychol Rev. 2000;20(3):359-78.
 McCann D, Barrett A, Cooper A, Crumpler D, Dalen L, Grimshaw K, et al. Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community: a randomised, double-blinded, placebo-controlled trial. Lancet. 2007;370(9598):1560-7.
 Byun YH, Ha M, Kwon HJ, Hong YC, Leem JH, Sakong J, et al. Mobile phone use, blood lead levels, and attention deficit hyperactivity symptoms in children: a longitudinal study. PLoS One. 2013;8(3):e59742.