Objective: To present the results of a systematic review of literature published between 1980 and 2004 reporting findings of the prevalence and incidence of anxiety disorders in the general population.Method: A literature search of epidemiologic studies of anxiety disorders was conducted, using MEDLINE and HealthSTAR databases, canvassing English-language publications. Eligible publications were restricted to studies that examined age ranges covering the adult population. A set of predetermined inclusion and exclusion criteria were used to identify relevant studies. Prevalence and incidence data were extracted and analyzed for heterogeneity.Results: A total of 41 prevalence and 5 incidence studies met eligibility criteria. We found heterogeneity across 1-year and lifetime prevalence rates of all anxiety disorder categories. Pooled 1-year and lifetime prevalence rates for total anxiety disorders were 10.6% and 16.6%. Pooled rates for individual disorders varied widely. Women had generally higher prevalence rates across all anxiety disorder categories, compared with men, but the magnitude of this difference varied. Conclusion:The international prevalence of anxiety disorders varies greatly between published epidemiologic reports. The variability associated with all anxiety disorders is considerably smaller than the variability associated with individual disorders.Women report higher rates of anxiety disorders than men. Several factors were found to be associated with heterogeneity among rates, including diagnostic criteria, diagnostic instrument, sample size, country studied, and response rate. Clinical Implications · Significant heterogeneity in the prevalence of anxiety disorders signals the need for population-specific health policies and planning. · The prevalence of anxiety disorders eclipses the capacity of specialized mental health services. · Anxiety disorders remain prevalent throughout ages 18 to 64 years. Limitations· The observed heterogeneity may be related to environmental or cultural factors associated with the location of each contributing investigation. · Variance owing to methods of diagnosis and measurement account for a limited portion of the observed heterogeneity. · An insufficient number of incidence studies are available to clarify details concerning the onset of symptoms.

The prevalence of mood disorders reported in high-quality studies is generally lower than rates commonly reported in the general psychiatric literature. When controlled for common methodological confounds, variation in prevalence rates persists across studies and deserves continued study. Methodological variation among studies that have examined the prevalence of depression in primary health care services is so large that comparative analyses cannot be achieved.

SynthèseA ntipsychotic drugs are useful for treating a range of severe psychiatric disorders. Applications include the short-term treatment of acute psychotic, manic and psychotic-depressive disorders as well as agitated states in delirium and dementia and the long-term treatment of chronic psychotic disorders including schizophrenia, schizoaffective disorder and delusional disorders. Newer, "second-generation" antipsychotic drugs have largely replaced older phenothiazine, thioxanthene and butyrophenone neuroleptics in clinical practice (Table 1).1,2 The development of modern antipsychotic drugs was stimulated by a landmark 1988 study that showed clozapine to be superior in efficacy to chlorpromazine in schizophrenia patients resistant to high doses of haloperidol and to have none of the adverse neurologic effects typical of older antipsychotic agents.3 Clozapine was considered "atypical" in having a very low risk of adverse extrapyramidal symptoms. This term has since been applied broadly and uncritically to antipsychotic drugs marketed in the past decade, despite their striking chemical, pharmacologic and clinical heterogeneity. 4 In this overview we consider the neuropharmacology, efficacy and adverse effects of conventional antipsychotics and specific modern antipsychotic drugs. NeuropharmacologyThe venerable hypothesis that schizophrenia is caused by increased cerebral activity of the neurotransmitter dopamine was based primarily on the finding that dopamine agonists produced or worsened psychosis and that antagonists were clinically effective against psychotic and manic symptoms. 5 Blocking dopamine D 2 receptors may be a critical or even sufficient neuropharmacologic action of most clinically effective antipsychotic drugs, especially against hallucinations and delusions, but it is not necessarily the only mechanism for antipsychotic activity. Moreover, this activity, and subsequent pharmacocentric and circular speculations about altered dopaminergic function, have not led to a better understanding of the pathophysiology or causes of the several still idiopathic psychotic disorders, nor have they provided a non-empirical, theoretical basis for the design or discovery of improved treatments for psychotic disorders.The neuropharmacodynamics of specific modern antipsychotic drugs vary greatly, with little evidence for a unifying theory of antipsychotic activity or of drug design (Table 2). Clozapine in particular is complex: it binds loosely and transiently to D 2 receptors and interacts at dopamine (D 1 , D 3 and D 4 ), histamine (H 1 ), acetylcholine muscarinic (M 1 ) and serotonin (5-HT 2A , 5-HT 2C , 5-HT 6 and 5-HT 7 ) receptors and α 1 adrenoceptors. [6][7][8] This complexity leaves the very low risk of extrapyramidal symptoms and unexcelled antipsychotic effectiveness of clozapine unexplained.9 Postural dizziness, sedation and increased appetite may reflect actions of clozapine and some other antipsychotic agents at α 1 , H 1 and 5-HT 2C receptors respectively. Olanzapine demonstrates significant anti-...

Although we restricted this review to studies using rigorous and relatively homogeneous methods, there remains significant heterogeneity of prevalence and incidence rates. This strengthens support for the hypothesis that there is real variation in the distribution of schizophrenia around the world. Health planners need to have local data on schizophrenia rates to improve the accuracy of their interventions, while clinicians and researchers need to continue to investigate the etiology of this variation.

A n important foundation for planning and improving mental health services is a clear estimate of need (1). Although it has been well established that schizophrenic disorders produce a substantial need for mental health services (2), communities require accurate measures of the extent and distribution of such need in order to correctly allocate services. An underestimate of need could result in the tragic neglect of individuals who are suffering, and an overestimate could result in the misallocation of precious health resources.One approach might be to extrapolate prevalence estimates for schizophrenic disorders by applying the findings of large-scale epidemiologic studies arithmetically to local populations. However, the results of such formulaic calculations are unlikely to provide accurate estimates. As seems to be the case for all health problems studied, schizophrenic disorders are unequally distributed in communities (3). A recent systematic review of high-quality, large-scale epidemiologic studies that used similar methods to determine the incidence and prevalence of schizophrenic disorders produced varying rates (4). Furthermore, such differences in the aggregated data of large-scale studies, which often sample entire cities, states, provinces, or nations, do not demonstrate the considerable variability in rates across individual towns, communities, or neighborhoods-the so-called small-area variations. Small-area variations in the prevalence rates of schizophrenic disorders have been found to be substantial (5-7).Given the variation in the prevalence rates of schizophrenic disorders at the level of individual communities, how can planners estimate the appropriate level of resources to be allocated in a community? In this article we examine the use of administrative data-information routinely collected by health providers and governments-for the purpose of estimating the prevalence, incidence, and distribution of schizophrenic disorders. We also discuss the relative benefits and limitations of this method and discuss its utility in complementing rigorous epidemiologic surveys. Objective: In order to effectively plan and implement psychiatric services, a clear estimate of the prevalence and distribution of the population in need is required. The authors examined the use of administrative data as a means of estimating the prevalence and distribution of schizophrenic disorders. Methods: Administrative health services data for residents of the Canadian province of British Columbia in the age range 15 to 65 years (total population in 1997-1998 of 2,703,588) were examined over a three-year period. Potential cases of schizophrenic disorder were identified on the basis of the presence of a diagnostic code of 295 in one or more of three databases. One-year prevalence rates were estimated for each of the province's geographic regions, and associations with low income and unemployment were examined. Results: One-year prevalence rate estimates were .45 cases per 100 population in 1996-1997 and 1997-1998 and .42 cases...