Wow. Lots of psycho linguists around lately, huh? How about a change of pace? Think you guys can handle something not about Lord Chomsky?
Over the last one hundred years, paradigm shifts in the study of psychopathology have altered our conceptualization of attention deficit/hyperactivity disorder (ADHD), as a construct and as a diagnostic category. With few exceptions, it has generally been accepted that there is a brain-based neurological cause for the set of behaviors associated with ADHD. However, as technology has progressed and our understanding of the brain and central nervous system has improved, the nature of the neurological etiology for ADHD has changed dramatically. The diagnostic category itself has also undergone many changes as the field of psychopathology has changed.
In the 1920s, a disorder referred to as minimal brain dysfunction described the symptoms now associated with ADHD. Researchers thought that encephalitis caused some subtle neurological deficit that could not be medically detected. Encephalitis is an acute inflammation of the brain that can be caused by a bacterial infection, or as a complication of another disease such as rabies, syphilis, or lyme disease. Indeed, children presented in hospitals during an outbreak of encephalitis in the United States in 1917-1918 with a set of symptoms that would now be described within the construct of ADHD.
In the 1950s and 1960s, new descriptions of ADHD emerged due to the split between the neo-Kraepelinian biological psychiatrists and the Freudian psychodynamic theorists. The term hyperkinetic impulse disorder, used in the medical literature, referred to the impulsive behaviors associated with ADHD. At the same time, the Freudian psychodynamic researchers (who seem to have won the battle in the DSM-II) described a hyperkinetic reaction of childhood, in which unresolved childhood conflicts manifested in disruptive behavior. The term "hyperkinetic," which appears in both diagnoses, describes the set of behaviors that would later be known as hyperactive – despite the fact that medical and psychological professionals were aware that there were many children who presented without hyperactivity. In either case, it was the presenting behavior that was the focus – which was implicit, given the behavioral paradigm that guided the field.
When the cognitive paradigm became dominant, inattention became the focus of ADHD, and disorder was renamed attention deficit disorder (ADD). Two subtypes would later appear in the literature, which correspond to ADD with or without hyperactivity. The diagnostic nomenclature reflects the notion that the primary problem was an attentional (and thus, cognitive) one and not primarily behavioral. The attentional problems had to do with the ability to shift attention from one stimulus to another (something that Jonah Lehrer has called an attention-allocation disorder, since it isn't really a deficit of attention). The hyperactivity symptoms were also reformulated as cognitive: connected with an executive processing deficit termed “freedom from distractibility.”
In DSM-IV, published in 1994, the subtypes were made standard and there wasn’t much change in the diagnostic criteria per se, but there were changes in the name of the disorder, which reflected changes in the literature in terms of the understanding of the etiology of the disorder. The term ADD did not hold up, and the disorder became known as ADHD, with three subtypes: ADHD with hyperactivity/impulsiveness, ADHD with inattention, and a combined subtype in which patients have both hyperactive and attention-related symptoms. Due to improved neuroimaging technology, these subtypes seem to reflect structural and functional abnormalities found in the frontal lobe, and in its connections with the basal ganglia and cerebellum.
The set of the symptoms associated with ADHD seem not to have changed much in the last one hundred years. However, paradigm shifts within the field of psychopathology have changed the way in which researchers understand the underlying causal factors, as well as which of the symptoms are thought to be primary.