26 Chapter 2
hyperactivity or pervasive misery refers to problems that are present
in a range of different settings. In the term ‘pervasive developmental
disorder’, however, ‘pervasive’ refers primarily to the fact that multiple
domains of development are affected by autistic spectrum disorders (in
contrast to the specific developmental disorders affecting just one domain
of development, for example, reading or speech). This is confusing since
both sorts of developmental disorder (pervasive and specific) are pervasive
in the sense of being present in a range of different settings.
Classifying disordered individuals
or disordered families?
Aiming to find a diagnosis for the ‘identified patient’ might be focusing
attention on the wrong organisational level, for example, on one family
member rather than on the family system as a whole. Conversely, family
therapists might be making the opposite error in their formulations.
Multiaxial diagnostic systems potentially provide the best of both worlds
since they can record abnormalities at both the individual and the family
level. Unfortunately, there is no widely accepted and well-validated system
for classifying disordered families.
Diagnostic groupings: current practice
ICD-10 and DSM-IV
There are two main classifications in current use: the International Clas-
sification of Diseases (ICD) of the World Health Organization, and the
Diagnostic and Statistical Manual (DSM) of the American Psychiatric
Association. There used to be many differences between the two schemes
but they have converged on very similar classifications (ICD-10 and DSM-
IV). It is worth noting that ICD-10 comes as a clinical version that provides
clinical descriptions and somewhat impressionistic diagnostic guidelines
for each disorder, and as a research version that provides more clearly
defined diagnostic criteria, often identical to those used by DSM-IV. This
agreement owes at least as much to improved international collaboration
as to increased scientific knowledge. Fashion continues to be important
in classification and there are likely to be minor and major revisions of
the schemes for many years yet. Our current ideas are like early maps of
largely unexplored territory – better than nothing, provided you do not
take the details too seriously.
Operationalised diagnoses: pluses and minuses
DSM-IV and the research version of ICD-10 both provide operationalised
diagnostic criteria for many disorders. For each of these disorders, there are
clear criteria that must be fulfilled before the diagnosis can be made. The
main advantage of this approach is that different clinicians and researchers