The role of pharmacotherapy in the management of depressive disorders is well-established and frequently reviewed. This paper focuses on the prospects for reducing the incidence, prevalence and morbidity of depression through psychosocial interventions. A central requirement in prevention is a knowledge of the epidemiology of the disorder being investigated. This data can be used to identify high-risk groups. By comparing the number of known cases with population levels of morbidity, it allows comment on help-seeking behaviour and accessibility of services. Also, differences in incidence and prevalence rates give some indication of the chronicity of the disorder.

Since the introduction of lithium therapy 30 years ago it has become a major weapon in psychiatrists' armamentarium. It is the drug of first choice for the prevention of recurrent mood disorders, and it is estimated that about one person in every thousand people in Britain receives lithium at any one time. It therefore behoves doctors to be familiar with its use. This article is not a comprehensive account of the pharmacology of lithium (for this the reader is referred to Johnson (1987) and Peet & Pratt (1993)) but concentrates on its clinical use in practice and some less well known, but important, phenomena.

Advances in the understanding of the genetic causes of some neuropsychiatric disorders are having an impact on clinical practice as direct mutation analysis becomes possible. Mutation analysis is now available in UK Health Service diagnostic laboratories for Huntington's disease (HD) and the fragile X syndrome (FRAXA). Psychiatrists need to be familiar with issues surrounding presymptomatic and diagnostic testing in HD and diagnostic and carrier testing in FRAXA. They may be asked to assist clinical geneticists in the assessment of candidates for HD presymptomatic testing and a suggested mode of assessment is described here. The procedure for HD will provide the model for use with other familial neuropsychiatric disorders of late onset, notably familial Alzheimer's disease (FAD). Testing for FAD is already possible in conjunction with research laboratories in the few families where a mutation has been discovered and we shall have more tests for FAD within a few years.

The 1988 US Surgeon General's Report entitled Nicotine Addiction reviewed the mass of evidence on the role of nicotine in tobacco consumption and came to three main conclusions, shown in Box 1.