Anxiety Disorders: Beard JR

Nandi A, Beard JR, Galea S. · Center for Urban Epidemiologic Studies, New York Academy of Medicine, New York, USA. · BMC Psychiatry. · Pubmed #19486530 links to  free full text

Abstract: BACKGROUND: Clinical evidence has long suggested there may be heterogeneity in the patterns and predictors of common mood and anxiety disorders; however, epidemiologic studies have generally treated these outcomes as homogenous entities. The objective of this study was to systematically review the epidemiologic evidence for potential patterns of heterogeneity of common mood and anxiety disorders over the lifecourse in the general population. METHODS: We reviewed epidemiologic studies examining heterogeneity in either the nature of symptoms experienced ("symptom syndromes") or in patterns of symptoms over time ("symptom trajectories"). To be included, studies of syndromes were required to identify distinct symptom subtypes, and studies of trajectories were required to identify distinct longitudinal patterns of symptoms in at least three waves of follow-up. Studies based on clinical or patient populations were excluded. RESULTS: While research in this field is in its infancy, we found growing evidence that, not only can mood and anxiety disorders be differentiated by symptom syndromes and trajectories, but that the factors associated with these disorders may vary between these subtypes. Whether this reflects a causal pathway, where genetic or environmental factors influence the nature of the symptom or trajectory subtype experienced by an individual, or whether individuals with different subtypes differed in their susceptibility to different environmental factors, could not be determined. Few studies addressed issues of comorbidity or transitions in symptoms between common disorders. CONCLUSION: Understanding the diversity of these conditions may help us identify preventable factors that are only associated with some subtypes of these common disorders.

Beard JR, Galea S, Vlahov D. · New York Academy of Medicine, New York, New York, USA. · BMC Psychiatry. · Pubmed #18811958 links to  free full text

Abstract: BACKGROUND: Longitudinal, population-based, research is important if we are to better characterize the lifetime patterns and determinants of affective disorders. While studies of this type are becoming increasingly prevalent, there has been little discussion about the limitations of the methods commonly used. METHODS: Discussion paper including a brief review of key prospective population-based studies as the basis for a critical appraisal of current approaches. RESULTS: We identified a number of common methodological weaknesses that restrict the potential of longitudinal research to characterize the diversity, prognosis, and determinants of affective disorders over time. Most studies using comprehensive diagnostic instruments have either been of relatively brief duration, or have suffered from long periods between waves. Most etiologic research has focused on first onset diagnoses, although these may be relatively uncommon after early adulthood and the burden of mental disorders falls more heavily on individuals with recurring disorders. Analysis has tended to be based on changes in diagnostic status rather than anges in symptom levels, limiting study power. Diagnoses have generally been treated as homogeneous entities and few studies have explored whether diagnostic subtypes such as atypical depression vary in their etiology or prognosis. Little research has considered whether there are distinct trajectories of symptoms over time and most has focused on individual disorders such as depression, rather than considering the relationship over time between symptoms of different affective disorders. There has also been limited longitudinal research on factors in the physical or social environment that may influence the onset, recurrence or chronicity of symptoms. CONCLUSION: Many important, and in some respects quite basic, questions remain about the trajectory of depression and anxiety disorders over the life course and the factors that influence their incidence, recurrence and prognosis. Innovative approaches that consider symptoms of all affective disorders, and how these change over time, has the potential to greatly increase our understanding of the heterogeneity of these important conditions and of the individual and environmental characteristics that influence their life course. Using longitudinal research to define sub classes of affective disorders may also be of great benefit for studies seeking to define the genetic determinants of susceptibility to these conditions.

Ompad DC, Galea S, Marshall G, Fuller CM, Weiss L, Beard JR, Chan C, Edwards V, Vlahov D. · Center for Urban Epidemiologic Studies, New York Academy of Medicine, 1216 Fifth Avenue, New York, NY 10029-5283, USA. · J Urban Health. · Pubmed #18214686 links to  free full text

Abstract: Illicit drug use in urban settings is a major public health problem. A range of individual level factors are known to influence drug use and its consequences, and a number of recent studies have suggested that the neighborhood in which an individual lives may also play a role. However, studies seeking to identify neighborhood-level determinants of drug use, particularly among marginalized urban populations, need to overcome significant challenges, particularly in the area of sampling and recruitment. One key issue is defining functional neighborhoods that are relevant to local residents. Another arises from the need to sample a representative or even a diverse population when studying marginalized groups such as illicit drug users. These are common problems that raise particular challenges when both need to be addressed in the same study. For example, many sampling approaches for neighborhood-level studies have included some form of random sample of households, but this may systematically overlook marginalized populations. On the other hand, the sampling approaches commonly used in studies of hidden populations such as chain referral, snow ball, and more recently, respondent-driven sampling, typically expand beyond a geographic "neighborhood." We describe the organization and rationale for the IMPACT Studies in New York City as a case illustration on how such issues may be addressed.