The Evolution of Classification and Diagnostic Criteria

The Evolution of Classification and Diagnostic Criteria

In 1917 a pandemic of encephalitis lethargica swept across Europe and North America, and some of the children, who recovered from the brain inflammation, were reported to have developed cognitive deficits, and tended to be overactive, distractible, and prone to impulsive acts (Fitzgerald, Belgrave, & Gill, 2007).In the wake of this epidemic was an insurgence of academic and clinical interest in both aetiology and symptomology.

Creswell (1974) credits the events of 1917 with the subsequent decade’s emphasis on hyperactivity, and in all likelihood this is partial true, however, another plausible explanation is that it is the most notable (i.e., overt) symptom.  Thus, it is unsurprising that it was originally believed to be the most problematic (Fitzgerald, Belgrove, & Gill, 2007), and why educators continue to view it as such (DuPaul& Stoner, 2004), causing it to be the most commonly cited reason for the referral of young people to clinics in the USA (Brown, 2006; Cantwell, 1996).  In addition, when, quite by accident, Charles Bradley (1937) stumbled upon the calming effects Benzedrine had on overactive children the centrality of hyperactivity seems to have been firmly cemented.

The second edition of the DSM-II (APA, 1968) introduced the label Hyperkinetic Reaction of Childhood, replacing Minimal Brain Dysfunction (previously Minimal Brain Damage) due to the lack of observable brain abnormalities (Fitgerald, Belgrove, & Gill, 2007). The emphasis on motor activity and the use of ‘reaction’, supplanted the fields preoccupation with a supposed biological basis. The psychoanalytic leaning has since been discarded, but the preference for behaviourally based descriptions (i.e., symptom centred) continues today.  It was not until the 1970’s that the centrality of hyperkinesias was questioned by Virginia Douglas and her colleagues at McGill University in Canada.Following a battery of behaviour and cognitive measures on‘hyperkinetic’ and ‘normal’ children, the research team observed,

"... a core group of symptoms involving inability to sustain attention and to control impulsivity can account for most of the deficits found [in hyperactivity]..."(Douglas, 1972, p.1).

These findings along with the observed effects of stimulants on inattention were groundbreaking and have contributed to current appreciation of executive functioning deficits.  Thus, the third edition of the Diagnostic and Statistical Manual (DSM-III) published by the American Psychiatric Association (APA) in 1980, radically altered the definition of the condition to Attention Deficit Disorder (ADD), which presented with or without hyperactivity (Barkley, 2006).  As such, the diagnostic criteria also changed to reflect the emphasis on inattention as the defining features of the disorder.  Despite a peaked interest and research into the possibility of a unique and qualitatively different disorder, the term ADD fell out of favour quickly.  The validity of Douglas’ model, emphasising inattention as the core characteristic of ADHD, was questioned for its inability to account for all of the behavioural symptoms. Moreover, it was felt that de-emphasising hyperactivity, and to a lesser degree impulsivity, posed significant problems for differential diagnosis and treatment outcomes (Weiss &Hetchman, 1993). Thus, the condition became known by its current nomenclature attention deficit hyperactivity disorder in the 1987 revision of the DSM-III.  Indeed, the current version (DSM-IV; APA, 1994) does not require inattentive symptoms for a diagnosis of ADHD (the predominantly hyperactive-impulsive subtype).

ADHD has a long a distinguished past, and the validity of the diagnosis is supported by a storehouse of research findings in both the biological and behavioural sciences (Barkley, 2006). The constant reconceptualising of the disorder, particularly the research beginning in the latter half of the twentieth century, has created a wealth of knowledge about the disorder, and contributed to a vast array of discourses surrounding ADHD. In addition, the diagnostic criteria have been refined. In the beginning individuals were observed to have ‘the fidgets’ or suffer from moral defect, however, the realization that hyperactivity was central was further refined, to include our current appreciation of the role of inattention and impulsivity. There is little doubt that the future holds many more reconfigurations as investigation attempts to explicate the ADHD enigma, in terms of what it is and does.