190 Chapter 23
authority and adult norms, predisposing them to delinquency and sub-
stance abuse. An identity based on the rejection of adult values sometimes
seems to reflect the cumulative impact of criticism by parents, failure at
school, and subsequent identification with a delinquent peer group.
Sexual identity may not be completely clear to young people; surveys
suggest that while at least 3% are unambiguously homosexual, at least the
same number go through a period of bisexuality, which for the majority is
transient.
Solving problems and weathering stress
Though childhood has its own stresses, the transition to adulthood can
bring on many more: examinations, broken hearts, unemployment, or in-
tensified arguments with parents. Children who have not learned adaptive
ways of relating to others and dealing with crises, perhaps because their
parents also lacked the relevant skills, are likely to find the new stresses of
adolescence particularly hard to cope with. Violence, substance abuse and
self-harm can all be ways of defusing stress or temporarily dealing with
problems that cannot be solved more adaptively.
Epidemiology of adolescent psychiatric disorders
The Isle of Wight study of 14- and 15-year-olds remains the ‘classical’
epidemiological investigation of adolescent psychopathology (see Box
23.1). The main conclusions of this study have stood the test of time.
The point prevalence of major depressive episodes in adolescence was
2% on the Isle of Wight 30 years ago – and also 2% in the recent
British national surveys cited in Chapter 3. Other studies have reported
significantly higher prevalence rates for adolescent depression, though it is
not clear if this is because different studies have used different thresholds,
or if rates of depression do indeed vary substantially across space and
time. There is accumulating evidence for a ‘two population’ model of
adolescent conduct problems, involving a ‘hard core’ of individuals who
are behaviourally disordered before, during and after adolescence, plus a
larger number of previously well-adjusted individuals who go through a
relatively transient phase of rule breaking and antisocial behaviour during
adolescence.
Emotional and disruptive behavioural disorders are the most common
diagnoses in adolescence, as in middle childhood. These are covered in
the relevant chapters, as are two other problems that peak in adoles-
cence, namely, juvenile delinquency and deliberate self-harm. Chapters
24, 25, 26 are devoted to three conditions that are not covered elsewhere
and that are much more common in adolescence than in childhood:
schizophrenia, eating disorders (anorexia nervosa and bulimia nervosa)
and substance use.