The past two decades have witnessed an increasing interest in research on anxiety syndromes and disorders. Significant advances in basic and clinical research, accompanied by animated ongoing discussions about the most appropriate, reliable and valid way to classify and assess anxiety disorders, have changed our understanding of anxiety disorders and affected (or some might say confused) our research and treatment practice.

Cognitive deterioration is so commonly observed in the elderly that it is considered by many to be an inevitable feature of the ageing process. Some researchers have proposed that the senile dementias are the inevitable end-point of this process, should the person live long enough. The differentiation of normal cerebral ageing from disease process is important in the selection of control groups for research, and also for clinical decision-making. In the latter context it is important to ask at what level of dysfunction intervention should occur, and whether this should be active or palliative. Cognitive change in the elderly is here considered from biological, neuropsychological and epidemiological viewpoints. Current research suggests that senile dementia is the result of the interplay of genetically determined disease processes, ageing-related decline which may be regulated at a cellular level, and neuronal repair and compensation mechanisms. Therefore, to debate whether dementia is simply an extension of a normal ageing process or not is probably too simplistic an approach.

The National Health Service (NHS) was born on 5 July 1948, after a prolonged and difficult labour, and in 1949 it cost the Treasury all of $433 million, or 3.5% of Britain's gross domestic product. In 1997/98 it cost the Treasury $44203 million, 5.6% of gross domestic product, and on 5 July this year it celebrates its 50th anniversary with parades, speeches, television programmes, symposia, much nostalgia and a service of thanksgiving in Westminster Abbey.

In recent years, there has been a renewed interest in obsessive-compulsive disorder (OCD) among psychiatrists due to several factors. OCD is not a rare disease as was believed in former times. New epidemiological studies demonstrate that 1–2% of the adult population suffer from OCD. This result was confirmed by several epidemiological studies among different cultural environments which are summarised by Dr Bebbington in this supplement. Thus, OCD figures among the most common of mental disorders. Lately a unique category of disorders has emerged that share some common key features with OCD. These ‘obsessive-compulsive spectrum disorders’ and their treatments are characterised in Dr Hollander's paper.

There is mounting evidence of the massive global health burden of mental illness (Murray & Lopez, 1996; Jenkins, 1997). Within Great Britain, the Department of Health's overall objectives for mental illness were summarised as follows (Department of Health, 1993):

(a) To reduce the incidence and prevalence of mental disorders.

(b) To reduce the mortality associated with mental disorders.

(c) To reduce the extent and severity of other problems associated with mental disorders, for example:

(i) poor physical health;

(ii) impaired social functioning;

(iii) poor social circumstances;

(iv) family burden.

(d) To ensure appropriate services and interventions are provided.

(e) To reverse the public's negative perception of mental illness, for example:

(i) counter fear, ignorance and stigma;

(ii) create a more positive social climate in which to seek help;

(iii) improve quality of life for people with mental health problems.

(f) To research causes, consequences and care of specific mental disorders.

Background Mental disorders impose a multi-billion dollar burden on the economy each year; translating the burden into economic terms is important to facilitate formulating policies about the use of resources.

Method For direct costs, data were obtained from national household interview and provider surveys; for morbidity costs, a timing model was used that measures the lifetime effect on current income of individuals with mental disorders, taking into account the timing of onset and the duration of these disorders, based on regression analysis of Epidemiologic Catchment Area study data.

Results The total economic costs of mental disorders amounted to US$ 147.8 billion in 1990. Anxiety disorders are the most costly, amounting to $46.6 billion, or 31.5% of the total; schizophrenic disorders accounted for $32.5 billion, affective disorders for $30.4 billion, and other mental disorders for $38.4 billion.

Conclusions Mental illnesses, especially anxiety disorders, are costly to society. Although anxiety disorders have a higher prevalence than affective disorders and schizophrenia, use of medical care services is lowest for anxiety disorders. Anxiety disorders appear to be under-recognised and untreated even though treatment interventions have been shown to be effective and can be delivered in a cost-efficient manner.

Post-traumatic stress disorder (PTSD) is a condition that appears to be becoming increasingly prevalent in psychiatric and general practice. Davidson (1992) reports a lifetime prevalence of 1–9% in the community, with high levels of chroniciry and comorbidity. It routinely features in the general as well as medical literature following major traumas such as the Herald of free enterprise disaster. PTSD is also growing more important in medicolegal terms, as the recent police attempt to obtain compensation for their experiences in the Hillsborough tragedy demonstrates. Despite the high profile of the condition and the repeated descriptions of its development and (partial) resolution after every major disaster, there is very little research into the most effective means of preventing or treating PTSD. The usual approach of debriefing has been shown to be without effect (Deahl et al, 1994) and a recent review of drug treatments revealed only a few small-scale studies, none of which would be suitable tor [he licensing of a drug for this disorder (Davidson, 1992). This may be because most drug treatments are initiated well after the trauma, which may be too late to prevent the laying down of immutable brain traces for the memories, behaviours and affect that trauma causes and which develop into PTSD.

Background Although the concept of obsessive-compulsive disorder (OCD) has long been established, research diagnostic criteria are relatively recent developments. This is partly because the symptoms of OCD occur in the context of other disorders and it is arguable to what extent they are relatively discrete phenomena.

Method Review of the existing epidemiological surveys based on standardised instruments.

Results Nine population surveys using the Diagnostic Interview Schedule have given data on OCD, with six-month prevalences ranging from 0.7 to 2.1%. The British National Survey of Psychiatric Morbidity based on the CIS – R gave a one-month prevalence of 1% in males and 1.5% in females. Community surveys show an excess of females and emphasise the early age of onset. Minor obsessional symptoms are considerably more common than OCD itself.

Conclusions OCD is fairly rare in the general population, but causes considerable distress to those who suffer from it.

The value of public and private investment in clinical health services and economic research, which aims to reduce the burden of illnesses on patients, their families and society as a whole, is an issue that is currently being debated at national and international levels.

The Government emphasis on tackling health inequalities and the availability of recent data on mental health inequalities from the Office of Population Censuses and Survey's (OPCS) National Psychiatric Morbidity Survey (NPMS) (Meitzer et al, 1995) suggest that it is time to review the evidence on inequalities in mental health. We aim to summarise the relevant research on rates of psychiatric morbidity within the general population, and define specific populations at high risk of mental disorder. The theories put forward to account for these inequalities are considered, noting the limitations of the data they are based on and highlighting their implications for the data required to facilitate further research. Inequalities in access, provision and appropriateness of services are also discussed. We make policy recommendations for reducing these inequalities at national, regional and district levels.

Background Obsessive-compulsive spectrum disorders (OCSDs) are now recognised as distinct diagnostic entities related to obsessive-compulsive disorder (OCD). The features of OCSDs and OCD overlap in many respects including demographics, repetitive intrusive thoughts or behaviours, comorbidity, aetiology and preferential response to anti-obsessional drugs such as the selective serotonin reuptake inhibitors (SSRIs).

Method Literature was reviewed and preliminary data from various studies were re-examined to assess the relationship between compulsivity and impulsivity, and between OCD and OCSDs.

Results OCSDs include both compulsive and impulsive disorders and these can be viewed as lying at opposite ends of the dimension of risk avoidance. Compulsiveness is associated with increased frontal lobe activity and increased serotonergic activity, while impulsiveness is associated with reduced activity of these variables. Neural circuits affected by serotonergic pathways have been identified and pharmacological challenge of OCSD patients with serotonin receptor agonists have supported the involvement of serotonergic processes.

Conclusions SSRIs such as fluvoxamine have established efficacy in OCD and preliminary studies indicate that they are also effective in OCSDs. The features of three specimen OCSDs –body dysmorphic disorder, pathological gambling and autism – and their treatment with SSRIs are reviewed.