206 Chapter 26
sensitive to repeated alcoholic binges, with hippocampal cell loss, poten-
tially resulting in impaired memory and learning.
Causation
There is no single or simple explanation for the pattern of substance
use: price, availability, addictiveness, constitutional predisposition, youth
culture, advertising and adult role models all play a part. Prior psychosocial
adjustment is one more factor amongst many. Children and adolescent
with disruptive behavioural disorders are more liable to become heavy
substance users and go on to develop associated complications. The com-
bination of conduct disorder and ADHD carries a particularly high risk. In
contrast to this clear link between externalising disorders and substance-
related problems, the link between emotional disorders and substance
abuse is more complex. Some emotional disorders may predispose ado-
lescents to substance use, as when individuals with social anxiety use
alcohol to ‘treat’ this anxiety. On the other hand, the main link between
emotional disorders and substance use is probably in the reverse direction,
with established substance abuse being a risk factor for depression.
Substance use disorders
Psychiatric classifications are less concerned with the ‘ordinary’ use of
substances than with the identification of pathological patterns of use that
can be classified as asubstance use disorder. The approach taken by ICD-10
and DSM-IV is ingenious but imperfect. One of the challenges facing any
classification of substance use disorders is that there are many relevant
substances – and more are being added all the time. If the classification
of substance use disorders differed markedly for every single substance,
the system could easily end up too complex for most practitioners to
understand and remember – and even the best of classifications would be
of little value if most people found it too complex to use. To get round this
problem, both ICD-10 and DSM-IV apply some broad principles to defining
four syndromes that could potentially apply to any substance (though
some syndromes are irrelevant to some substances). The four syndromes
are:
1 Dependence: This syndrome refers to a pattern of repeated use that
can lead to tolerance, withdrawal symptoms, and compulsive use. The
detailed ICD-10 criteria are shown in Box 26.2.
2 Harmful use: The ICD-10 term ‘Harmful use’ is equivalent to ‘Abuse’
in DSM-IV. This syndrome refers to individuals who do not meet the
full criteria for dependence, but whose pattern of substance use has
nevertheless clearly led to physical or psychological harm. The harmful
pattern of use needs to have persisted for over a month, or occurred
repeatedly within a 12-month period. The harm may have been brought