The burden of celiac disease (CD) is increasingly recognized as a global problem. However, whether this situation depends on genetics or environmental factors is uncertain. The authors examined these aspects in Sweden, a country in which the risk of CD is generally considered to be high. If environmental factors are relevant, CD risk in second-generation immigrant children should be related to maternal length of stay in Sweden before delivery.
Linking the Swedish Medical Birth Registry to other national registries, the authors investigated all singleton children (n = 792,401) born in Sweden between 1987 and 1993. They studied the risk of CD in children before age 6 as a function of the mother's geographical region of birth and length of stay in Sweden before delivery using Cox regression models.
In children whose mothers immigrated to Sweden from a country outside of Europe, a maternal length of stay in Sweden of more than 5 years increased the hazard ratio (HR) of CD (1.73, 95% confidence interval (CI) 1.06-2.81). The authors observed a similar result among children born to mothers from a Nordic country outside of Sweden (HR 1.57, 95% CI 0.89-2.75), but a non-conclusive protective effect was observed in second-generation immigrant children from a non-Nordic European country (HR 0.65, 95% CI 0.39-1.09).
The risk of CD among second-generation immigrants seems to be conditioned by maternal length of stay in Sweden before delivery, suggesting that environmental factors contribute to the variation in CD risk observed across populations.
Age, period, and cohort effects for future employment, sickness absence, and disability pension by occupational gender segregation: a population-based study of all employed people in a country (>?3 million).
The occupational gender segregation of the labour market is very strong, both in Sweden and in North America. Nevertheless, there is little knowledge on how this is associated with employees' future employment or morbidity. The objectives of this study were to explore age, period, and cohort effects on future employment and morbidity in terms of sickness absence (SA) or disability pension (DP) among women and men employed in numerically gender-segregated or gender-integrated occupations.
Based on Swedish nationwide register data, three population-based cohorts of all people living in Sweden, with a registered occupation, and aged 20-56 years at inclusion in 1985 (N?=?3,183,549), 1990 (N?=?3,372,152), or 2003 (N?=?3,565,579), respectively, were followed prospectively for 8 years each. First, descriptive statistics of employment and SA/DP at follow-up were calculated, related to level of gender segregation/integration of occupation at inclusion. Second, differences between birth cohorts (those born in 1929-1983, respectively) were estimated within each of the periods 1985-1993, 1990-1998, and 2003-2011, using mean polish analyses.
Women and men in gender-segregated occupations differed in relation to future employment rates and SA/DP. However, these differences decreased over time. Furthermore, the results show a birth cohort effect; those born in 1943-1956 remained in employment to a higher extent and also had lower rates of SA/DP than all other birth cohorts.
Differences between people in the five categories of gender-segregated occupations decreased over time. Although age and period are important when explaining the outcome, also birth cohort effects have to be considered, both from a public and an occupational health perspective.
Russian suicide mortality rates changed rapidly over the second half of the twentieth century. This study attempts to differentiate between underlying period and cohort effects in relation to the changes in suicide mortality in Russia between 1956 and 2005.
Sex- and age-specific suicide mortality data were analyzed using an age-period-cohort (APC) approach. Descriptive analyses and APC modeling with log-linear Poisson regression were performed.
Strong period effects were observed for the years during and after Gorbachev's political reforms (including the anti-alcohol campaign) and for those following the break-up of the Soviet Union. After mutual adjustment, the cohort- and period-specific relative risk estimates for suicide revealed differing underlying processes. While the estimated period effects had an overall positive trend, cohort-specific developments indicated a positive trend for the male cohorts born between 1891 and 1931 and for the female cohorts born between 1891 and 1911, but a negative trend for subsequent cohorts.
Our results indicate that the specific life experiences of cohorts may be important for variations in suicide mortality across time, in addition to more immediate effects of changes in the social environment.
Cites: Suicide Life Threat Behav. 1994 Fall;24(3):275-817825200
Cites: Int J Epidemiol. 1996 Aug;25(4):814-208921461
In Sweden, alcohol abstention has increased over the last 20 years and consumption has recently decreased after a peak in 2004. To understand the dynamics of these trends the present study aims at estimating age, period and cohort (APC) effects on trends in alcohol use prevalence as well as overall and beverage-specific volume of drinking over the last three decades.
APC analysis of seven cross-sectional surveys from 1979 to 2011 was conducted using cross-classified random effects models (CCREMs) by gender. The nationally representative samples comprised 77,598 respondents aged 16-80 years. Outcome measures were 30-day prevalence of alcohol use and overall as well as beverage-specific alcohol volume.
Trends in prevalence, overall and beverage-specific volume were significantly affected by APC. The period effects of prevalence and overall volume show a small decline after an increase up to the year 2005. Mean beer and wine volume levelled off after a peak in 2005 and volume of spirits drinking decreased constantly. Predicted alcohol prevalence rates in male cohorts (1945-1985) remained generally at the same level, while they declined in post-World War II female generations. Results point to high overall and beverage-specific consumption among cohorts born in the 1940s, 1950s and 1980s.
High consuming cohorts of the 1940-1950s were key in rising consumption up to 2005. Progression through the life course of these cohorts, a decrease in prevalence and drinking volume in successive cohorts seem to have contributed to the recent downward trend in alcohol use in Sweden.
The Nordic countries have experienced a steady increase in breast cancer incidence throughout the past 35 years. We analysed the incidence in Denmark, Finland, Norway and Sweden during the period 1958 to 1992 using age-period-cohort models and taking the systematic mammography screening into account. Assuming the age dependency of the incidence pattern in old age to be common for the Nordic countries, an internal comparison could be made among the four countries of the cohort effects and the period effects. The study indicated that the period effects have been of importance for the increase in breast cancer incidence seen in the Nordic countries. The widespread practice of neglecting the period effects in age-period-cohort analysis of time trends in breast cancer incidence therefore probably needs reconsideration. A key finding was that Danish women born in the 20th century seem to have been exposed to an increasing load of cohort borne breast cancer risk factors not experienced to the same extent by Norwegian women, whereas they were seemingly subjected to the same period effects.
Findings from animal and human studies indicate that anxiety and stress have a negative influence on the child and mother. The aim of this study was to explore the risk for having an anxiety diagnosis and the impact of the diagnosis in a three generational perspective.
The information was retrieved from Swedish population-based registries. All women who gave birth between 1973 and 1977 (n 169,782), their daughters (n 244,152), and subsequently also the offspring of the daughters (n 381,953) were followed until 2013.
We found that 4% of the mothers and 6% of the grandmothers had been diagnosed with anxiety. Women who had mothers with an anxiety disorder were more than twice as likely to have an anxiety disorder themselves compared to all other women (OR?=?2.20, 95% CI?=?2.04-2.30). In the third generation, the children born to mothers with an anxiety disorder, the odds ratio of being diagnosed with anxiety was more than twice as high than for the rest of the population (OR?=?2.54, 95% CI?=?2.01-3.20). If both the mother and the grandmother had had an anxiety disorder the odds ratio for the child having a diagnosis of anxiety was three times higher (OR?=?3.11, 95% CI?=?2.04-4.75). Anxiety diagnosis in the two previous generations also increased the likelihood of the child having either more than two inpatient visits or more than 10 outpatient visits (OR?=?2.64, 95% CI?=?2.40-2.91 and OR?=?2.21, 95% CI?=?2.01-2.43, respectively).
The intergenerational effect on anxiety is high. In order to minimize the risk for further transmission of anxiety disorders, increased awareness and generous use of effective treatment regimes might be of importance.
Environmental variation can generate life-long similarities among individuals born in the same breeding event, so-called cohort effects. Studies of cohort effects have to account for the potentially confounding effects of current conditions (observation year) and age of individuals. However, estimation of such models is hampered by inherent collinearity, as age is the difference between observation year (period) and cohort year. The difficulties of separating linear trends in any of the three variables in Age-Period-Cohort (APC) models are the subject of ongoing debate in social sciences and medicine but have remained unnoticed in ecology. After reviewing the use of APC models, we investigate the consequences of model specification on the estimation of cohort effects, using both simulated data and empirical data from a long-term individual-based study of reindeer in Svalbard. We demonstrate that APC models are highly sensitive to the model's treatment of age, period and cohort, which may generate spurious temporal trends in cohort effects. Avoiding grouping ages and using environmental covariates believed to be drivers of temporal variation reduces the APC identification problem. Nonetheless, ecologists should use caution, given that the specification issues in APC models may have substantial impacts on estimated effect sizes and therefore conclusions.
Later-born cohorts of older adults tend to outperform earlier born on fluid cognition (i.e., Flynn effect) when measured at the same chronological ages. We investigated cohort differences in level of performance and rate of change across three population-based samples born in 1901, 1906, and 1930, drawn from the Gerontological and Geriatric Population Studies in Gothenburg, Sweden (H70), and measured on tests of logical reasoning and spatial ability at ages 70, 75, and 79 years. Estimates from multiple-group latent growth curve models (LGCM) revealed, in line with previous studies, substantial differences in level of performance where later-born cohorts outperformed earlier born cohorts. Somewhat surprisingly, later-born cohorts showed, on average, a steeper decline than the earlier-born cohort. Gender and education only partially accounted for observed cohort trends. Men outperformed women in the 1906 and 1930 cohorts but no difference was found in the 1901 cohort. More years of education was associated with improved performance in all three cohorts. Our findings confirm the presence of birth cohort effects also in old age but indicate a faster rate of decline in later-born samples. Potential explanations for these findings are discussed.
Body mass index (BMI) and intelligence quotient (IQ) are associated. We examined whether this association varied by birth cohort.
Among 37,414 Danish conscripts, the association between BMI and IQ overall and by birth cohort was examined. IQ was measured by the Børge Prien's Prøve (BPP) group intelligence test score.
Compared with men of normal BMI, mean differences (95% CI [confidence interval]) in BPP score were -0.6 (-1.1;-0.1) for underweight men; -0.8 (-1.1;-0.5) for overweight men; and -2.0 (-2.4;-1.5) for men with obesity. Crude prevalence ratios (95% CI) for low cognitive scores associated with obesity were, respectively, 1.52 (1.24; 1.85), 1.64 (1.32; 2.04), 1.56 (1.38; 1.76), and 1.35 (1.18; 1.54) among men born in 1955, 1965-1969, 1970-1979, and 1980-1984. Confounding by familial BMI or IQ could not be controlled.
The association between BMI and IQ is subject to secular trends.
This study evaluates cancer mortality among women employed in two large printing plants in Moscow.
A total of 3,473 women who were actively employed as of December 31, 1978, with a minimum of 2 years employment were followed from 1 January 1979 to 31 December 1993. There were 47,791 person-years observed, with only 51 women lost to follow-up (1.5%). Standardized mortality ratios (SMRs) were calculated using the population of Moscow to generate expected numbers. Analyses by job (compositors, press operators, and bookbinders), age hired, latency, and duration of employment were conducted.
Among women employed in the two printing plants, there was a significant excess of esophageal cancer, based on seven deaths (expected = 2.7, SMR = 2.7, 95% CI = 1.1-5.4). Four of the seven esophageal cancer deaths occurred among bookbinders (expected = 1.0, SMR = 4.1, 95% CI = 1.1-10.4), all among workers hired before 1957 (expected = 0.6, SMR = 7.1, 95% CI = 1.9-18.3), the last year benzene was used in bookbinding. Ovarian cancer was also significantly elevated among bookbinders (12 observed, 4.2 expected, SMR = 2.9, 95% CI = 1.5-5.0), which, along with one death from mesothelioma of the abdomen, might be related to the use of asbestos-contaminated talc fillers in paper. Press operators had significantly elevated mortality from stomach cancer (observed = 9, expected = 4.1, SMR = 2.2, 95% CI = 1.0-4.2) and, based on two deaths each, melanoma and bladder cancer.
Women in this printing industry cohort experienced excess mortality of cancer of the esophagus and stomach, with suggested increases of melanoma and bladder cancer. Further follow-up of this cohort, which would allow more in-depth analysis of rare cancer sites, latency, and duration of employment, is warranted. Gender comparisons within the cohort should also be conducted to clarify the role of occupational and lifestyle factors in the etiology of cancer among workers in the printing industry.