American journal of epidemiology
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A prospective cohort of 74,332 men and women was used to investigate the association of body mass index and height with suicide, anxiety, and depression. Participants in the Nord-Trøndelag Health Study (Norway, 1984-1986) (HUNT 1) were aged 20 years or more and followed up until December 31, 2002. Anxiety and depression were measured with the Hospital Anxiety and Depression Rating Scale (HADS) in 1995-1997. ⋯ In fully adjusted models, there was no association of height with the incidence of suicide or depression. Raised body mass index is associated with an increased risk of depression but reduced risk of suicide in men and women. The mechanisms underlying these different associations require clarification.
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Cuba's economic crisis of 1989-2000 resulted in reduced energy intake, increased physical activity, and sustained population-wide weight loss. The authors evaluated the possible association of these factors with mortality trends. Data on per capita daily energy intake, physical activity, weight loss, and smoking were systematically retrieved from national and local surveys. ⋯ During 1997-2002, there were declines in deaths attributed to diabetes (51%), coronary heart disease (35%), stroke (20%), and all causes (18%). An outbreak of neuropathy and a modest increase in the all-cause death rate among the elderly were also observed. These results suggest that population-wide measures designed to reduce energy stores, without affecting nutritional sufficiency, may lead to declines in diabetes and cardiovascular disease prevalence and mortality.
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Family history information is often incomplete in population-based disease registers because of truncation and/or missing family links. In this study, the authors simulated complete populations of related individuals with realistic age, family structure, and incidence rates. After mimicking the realities of register-based data, such as left truncation of family history and missing family links due to death, the authors explored recovery of familial association parameters from standard epidemiologic models. ⋯ One can safeguard against bias by starting follow-up later, with the number of registration years to be ignored in the analysis depending on the value of familial risk. The missing familial links due to death had no effect, except when there was differential mortality for cases with and without a family history of disease. In summary, truncation, and to a lesser extent missing family links, induces bias in familial risk estimates from population-based registers.
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Concern over the impact of flawed measurement continues to nag epidemiology. Early studies indicated that the impact of measurement error is benign, leading generally only to attenuation of associations; more recent research has documented that this impact, especially within the setting of multivariate modeling, cannot be expected always to be benign. It can, for example, be a source of unsettling inconsistency. Fewell and colleagues (Am J Epidemiol 2007;166:646-655) show that residual confounding is especially persistent in the presence of multivariate confounding.
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Oxidative stress contributes to dopaminergic neuron degeneration in Parkinson's disease. Urate, a potent antioxidant, could be neuroprotective. To determine whether higher plasma concentrations of urate predict a reduced risk of Parkinson's disease, the authors conducted a nested case-control study among participants in the Health Professionals Follow-up Study, a cohort comprising over 18,000 men who provided blood samples in 1993-1995. ⋯ After adjustment for age, smoking, and caffeine, the rate ratio of Parkinson's disease for the highest quartile of uricemia compared with the lowest was 0.43 (95% confidence interval: 0.18, 1.02; p(trend) = 0.017). This association was stronger in analyses excluding cases diagnosed within 4 years (median) from blood collection (rate ratio = 0.17, 95% confidence interval: 0.04, 0.69; p(trend) = 0.010). These results suggest that high plasma urate concentrations may decrease the risk of Parkinson's disease, and they raise the possibility that interventions to increase plasma urate may reduce the risk and delay the progression of Parkinson's disease.