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37 Epidemiology of DSM-Ill PDs
might be used to establish conshuct validity. Biological markers will also
be important in future research as another source of external validation.
Another method of validation is to determine whether the course or
natural history of PDs justifies their differentiation. Few such studies
have been done, because of the time and wst of prospective designs. hut
longitudinal studies can pmvide information not available from crosssectional
ones. They could identify predictors of future PDs, modifying
variables, and medical and social service needs. They also offer an
opportunity to examine the effect of temperament as an important predisposing
variable. Another issue that wuld be explored in this way is
the temporal stability of PDs. Although as defined in the ICD-l0 and
DSM-111, PDs are long-lasting disorders, very limited data are available
regarding this. For this reason it would be worth investigating the epidemiology
of PDs in different age groups, as an indication of the course
of PDs. Longitudinal studies will also provide evidence for the validity
of the concept of PD as constant maladaptive behaviour across time and
environmental circumstances."
Finally, treatment response is also a validator. Although PDs are considered
stable and long lasting, it is possible that effective treatments will
ultimately be developed, as with other psychiatric disorders, and treatment
response could also be used to validate the different types of PD.
There has been a remarkable advance in our understanding of the epidemiology
of PDs in the last few years. As this continues, we should better
understand not only the PDs, but also other mental disorders.
References
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Disorders: Diagnosis. Management andcourse. London: Wrighf 1988.
2 Metikangas, K.R. & Weissman, M.M. Epidemiology of DSM-111 Axis 11 personality
disorders. In: Frances, A.J. & Hales, R.E. (eds), APA Annual Review, vol. 5.
Psychiarry Update, pp. 258-78. Washington, DC: American Psychiauic Press.
1986.
3 Merikangas. K.R. Epidemiology of DSM-111 personality disorders. In Michels,
R. er al., (eds.). Psychiatry, v01 3, pp 1-16. Philadelphia: Lippincott, 1989.
4 Weissman, M.M. The epidemiology of personality disorders: A 1990 update.
Journal ofPersonalily Disorders. 1993; 7.4462.
5 Andrwli, A., Glessot, G., Aapro. N., Tricot, L. & Gognalons, M.Y. Personality
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6 Reich. J.H. & Green, A.I. Effect of personality disorders on outcome of treatment.
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