Robert D. Oades
Department of Human Physiology,
Finders University Medical Centre,
Bedford Park, Australia

What is the nature of the condition, referred to as attention deficit disorder (ADD)
or childhood hyperkinesis in this chapter? Recent categorical descriptions in di-
agnostic manuals are widely felt by clinicians to be misleading (e.g. ADD, minimal
brain dysfunction, childhood hyperkinesis). Indeed in contrast to conditions like
Parkinsonism, there is little clear knowledge of the underlying disorder. There
are symptoms. But no single one is indispensable for diagnosis and the number
necessary varies with the authority.

The measurable items of interest include motor activity, attentional strategies,
context-dependent motivation and psychostimulant responsiveness. An arbitrary
degree of deviation from the norm for several of these items currently forms the
basis for diagnosis (e.g., from fidgetiness to pervasive hyperkinesis) and hence
leads to the rather different estimates of the incidence of the condition around
the world ( Weiss ∧ Hechtman, 1979; Thorley, 1984).

If we seek biological concomitants or symptoms to model we cannot overlook
the questions raised by differences of clinical opinion. For example, at the mild
end of the scale, is there a symptom in "underachievement" (cf. Shaywitz ∧
Shaywitz, this volume)? This is a question for society and for the laboratory in-
vestigator. Is it relevant that after a given intervention an animal learns more
slowly or that learning one task interferes with learning another? At the severe
end of the scale, should the investigator be more concerned with pervasive hyper-
kinesia and/or autistic behaviour, mental handicap and/or responsiveness to psy-

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