Inger Katrine Dahl-Petersen

Physical activity patterns in Greenland : A country in transition

Aims: To examine differences in physical activity patterns among Inuit in Greenland in relation to social transition. The Inuit in Greenland are an indigenous population in the circumpolar north who are experiencing rapid social transition. Methods: Physical activity patterns were assessed by the International Physical Activity Questionnaire (long version). The population was divided into six groups according to different stages of social change, measured on the basis of education, current residence and occupation. Data were collected in a country-wide cross-sectional population survey among adult Inuit in Greenland from 2005 to 2009. Results: Men with long vocational or academic education living in towns (latest stage of social change) spent significantly less time on occupational physical activity (p = 0.001) compared with hunters and fishermen in villages (earliest stage of social change) (trend test p = 0.01). Women in the latest stage of change spent significantly less time on domestic physical activity (p < 0.001) (trend test p = 0.06) compared with women in the earliest stage of social change. This was also found for physical activity during transportation (p = 0.02 and p = 0.01 for men and women, respectively). No significant difference was found for leisuretime physical activity. Men and women in the latest stage of social change spent more time on sedentary activity (p < 0.001). Conclusions: Differences in physical activity patterns among Inuit in Greenland included decreasing time spent on domestic and occupational physical activity and increasing time spent on sedentary activities along with social change. Knowledge of changes in physical activity patterns in relation to social transition is important in prevention of obesity, type 2 diabetes and lifestyle diseases.

Validity of the International Physical Activity Questionnaire in the Arctic.

PURPOSE Information about physical activity (PA) in Greenland is limited, partly because of a lack of validated instruments in countries with non-Western living conditions. We modified the long form of the International Physical Activity Questionnaire (IPAQ-L) to arctic living conditions. The aim of the study was to compare IPAQ-L estimates with combined accelerometry and heart rate monitoring (ACC + HR) in a population-based study of adult Inuit in Greenland. METHODS Cross-sectional data were collected by face-to-face interview and ACC + HR monitoring among Inuit (18 yr and above) in Greenland during 2005-2010 (n = 1508). PA energy expenditure (PAEE) and time spent sedentary and on PA at moderate and vigorous intensity were derived from IPAQ-L and ACC + HR. Estimates were compared using Bland-Altman agreement analysis and Spearman correlations stratified by sex, place of residence (capital, towns, and villages), and age groups. RESULTS Questionnaire-based PAEE was moderately correlated with objectively measured PAEE (r = 0.20-0.35, P < 0.01). Self-reported time spent at moderate- and vigorous-intensity PA and time spent sedentary were weakly correlated with the objective measure (r = 0.11-0.31). Agreement analyses showed relatively small median differences for all measures of PA; however, time spent at moderate-intensity PA was substantially overreported by IPAQ-L when including walking (>1.5 h·d, P < 0.001) but not when excluding walking. CONCLUSIONS The IPAQ-L adapted to arctic living conditions in Greenland had a moderate level of agreement with combined accelerometry and heart rate monitoring for total PAEE at population level, but it was less valid to measure different intensities of PA and sedentary activity. Validity did not differ markedly between rural and urban communities.

Cardiovascular Disease Susceptibility and Resistance in Circumpolar Inuit Populations

Cardiovascular disease (CVD) is a major public health issue in indigenous populations in the Arctic. These diseases have emerged concomitantly with profound social changes over the past 60 years. The aim of this study was to summarize the literature on CVD risk among Arctic Inuit. Literature on prevalence, incidence, and time trends for CVD and its risk factors in Arctic Inuit populations was reviewed. Most evidence supports a similar incidence of coronary heart disease and a higher incidence of cerebrovascular disease among Arctic Inuit than seen in western populations. Factors that may increase CVD risk include aging of the population, genetic susceptibility, and a rapid increase in obesity, diabetes, and hypertension in parallel with decreasing physical activity and deterioration of the lipid profile. In contrast, and of great importance, there has been a decrease in smoking and alcohol intake (at least documented in Greenland), and contaminant levels are declining. Although there have been marked socioeconomic and dietary changes, it remains unsolved and to some extent controversial how this may have influenced cardiovascular risk among Arctic Inuit. The increase in life expectancy, in combination with improved prognosis for patients with manifest CVD, will inevitably lead to a large increase in absolute numbers of individuals affected by CVD in Arctic Inuit populations, exacerbated by the rise in most CVD risk factors over the past decades. For preventive purposes and for health care planning, it is crucial to carefully monitor disease incidence and trends in risk factors in these vulnerable Arctic populations.

Loss-of-function variants in ADCY3 increase risk of obesity and type 2 diabetes

We have identified a variant in ADCY3 (encoding adenylate cyclase 3) associated with markedly increased risk of obesity and type 2 diabetes in the Greenlandic population. The variant disrupts a splice acceptor site, and carriers have decreased ADCY3 RNA expression. Additionally, we observe an enrichment of rare ADCY3 loss-of-function variants among individuals with type 2 diabetes in trans-ancestry cohorts. These findings provide new information on disease etiology relevant for future treatment strategies.Individuals from a Greenlandic Inuit population with homozygous loss-of-function variants in ADCY3 (adenylate cyclase 3) have increased risk for obesity and type 2 diabetes. Carriers of rare ADCY3 variants in trans-ancestry populations also show increased association with type 2 diabetes.

Physical activity energy expenditure is associated with 2-h insulin independently of obesity among Inuit in Greenland.

AIMS Indigenous populations throughout the Arctic are experiencing a rapid increase in the prevalence of obesity and type 2 diabetes. The role of physical activity in relation to glucose metabolism in Arctic populations is not well studied. We examined the association between objectively measured physical activity energy expenditure (PAEE) and glucose metabolism in a population-based study of adult Inuit in Greenland. METHODS Cross-sectional data were collected by combined accelerometry and heart rate monitoring (ACC+HR) among Inuit (18+ years) in Greenland during 2005-2010 (n=1545). PAEE was calculated and the associations with fasting glucose, 2-h glucose, fasting insulin, 2-h insulin concentrations and body composition were analysed by linear regression. RESULTS An inverse association between PAEE and fasting insulin, 2-h insulin, 2-h glucose, fat percentage, BMI and waist circumference (WC) was found after adjustments by age and sex. Only the association between PAEE and 2-h insulin remained significant after adjustment by WC (P=0.01), most pronounced at low levels of PAEE indicating a threshold around 35-40kJ/kg/day. No overall linear trend was found for fasting glucose and 2-h glucose. CONCLUSIONS This population-based study showed that PAEE was associated with 2-h insulin independently of obesity in an inverse dose-response relation. Insufficient physical activity may contribute to impaired glucose tolerance through a pathway including alterations in obesity and fat distribution. Both obesity and low levels of PAEE may be important contributing risk factors for the increasing prevalence of type 2 diabetes mellitus among Inuit in Greenland, but additional risk factors should be examined in this indigenous population.

How well does social variation mirror secular change in prevalence of cardiovascular risk factors in a country in transition

Objectives: The social and cultural transition among the Inuit in Greenland over the last generations has in ecological studies been linked to changes in cardiovascular risk factors. To permit analyses at the individual level, we propose a categorization of participants in a cross‐sectional study according to their relative position in the process of social change.

Physical Activity and Abdominal Fat Distribution in Greenland

Purpose We examined how total volume of physical activity and reallocation of time spent at various objectively measured intensities of physical activity (PA) were associated with overall and abdominal fat distribution in adult Inuit in Greenland. Methods Data were collected as part of a countrywide cross-sectional health survey in Greenland. A combined accelerometer and HR monitor measured total physical activity energy expenditure (PAEE) and intensities of PA (N = 1536). Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were assessed by ultrasonography. Isotemporal substitution modeling was used to analyze the association between substitution of 1 h of sedentary time to light- or moderate-intensity PA and 1 h light-intensity PA to moderate- or vigorous-intensity PA in relation to body mass index (BMI), waist circumference (WC), SAT, and VAT. Results A negative linear association was found for total PAEE and BMI, WC, VAT, and SAT. Exchanging 1 h of sedentary time with light-intensity PA was associated with lower WC (−0.6 cm, P = 0.01), SAT (−0.08 cm, P < 0.001), and VAT (−0.04 cm, P = 0.359). Exchanging light-intensity PA with vigorous-intensity PA resulted in −6.1-cm lower WC (P < 0.001), −0.7-cm lower VAT (P = 0.018) and −0.7-cm lower SAT (P < 0.001). When further adjusting for BMI, the associations were attenuated; however, most of them remained significant, and the directions were mostly unchanged. All 1-, 5-, and 10-min bouts of MVPA were negatively associated with overall and abdominal fat distribution. Conclusion Physical activity energy expenditure is associated with lower BMI, WC, and abdominal fat among Greenland Inuit. The importance of promoting an upward shift of the whole PA intensity distribution and to spur even short bouts of MVPA to limit excessive accumulation of SAT and VAT is highlighted.

Measuring social inequality in health amongst indigenous peoples in the Arctic. A comparison of different indicators of social disparity among the Inuit in Greenland

The purpose of the article is to compare different indicators of social position as measures of social inequality in health in a population sample from an indigenous arctic people, the Inuit in Greenland. Data was collected during 2005–2015 and consisted of information from 3967 adult Inuit from towns and villages in all parts of Greenland. Social inequalities for smoking and central obesity were analysed in relation to seven indicators of social disparity in four dimensions, i.e. education and employment, economic status, sociocultural position, and place of residence. For each indicator we calculated age-adjusted prevalence by social group, rate ratio and the concentration index. The indicators were correlated with Pearson’s r ranging from 0.24 to 0.82. Concentration indices ranged from 0.01 to 0.17. We could not conclude that one indicator was superior to others. Most of the indicators were traditional socioeconomic indicators used extensively in research in western countries and these seemed to be useful among the Inuit too, in particular household assets and job. Two sociocultural indicators developed for use among the Inuit and which included parameters specific to the indigenous peoples in the transition from a traditional to a modern life style proved to be equally useful but not superior to the traditional socioeconomic indicators. The choice of indicator must depend on what it is realistic to collect in the actual research setting and the use of more than one indicator is recommended. It is suggested to further develop culture specific indicators of social position for indigenous peoples.

Whole blood mercury and the risk of cardiovascular disease among the Greenlandic population

Background: Studies have found mercury to be associated with cardiovascular disease (CVD), however, primarily in populations with low exposure. The highest levels, and variations in the levels, of whole blood mercury (WBM) worldwide have been found in Greenland. We prospectively assessed the association between WBM and the risk of developing CVD in the Greenlandic population. Methods: We assessed the effects of WBM levels on incident CVD among 3083 Greenlandic Inuit, participating in a population‐based cohort study conducted from 2005 to 2010. WBM was measured at baseline. Participants were followed in the National Patient Registries for Denmark and Greenland and in the causes of death register for CVD events from inclusion in the study until CVD event, emigration, death or end of follow‐up (30/9–2013). Using Cox regression analyses, we calculated the incidence rates and the hazard ratio of CVD events according to WBM levels. Potential interactions with sex were also investigated. Results: The highest levels of WBM were found in men, who had a significantly higher median level (19 &mgr;g/L (IQR:1–44)), compared with women (15 &mgr;g/L (IQR: 1–32), (p < 0.001)). The crude hazard ratio (HR) for incident CVD was 1.00 (95% CI 1.00–1.00) for 5 &mgr;g/l increase in WBM. After adjusting for several potential confounders, there was still no association between WBM and incident CVD (HR 0.99; 95%CI:0.99–1.00). We found no interactions with sex. Conclusions: In a population with high levels of WBM, we found no association between WBM and the risk of developing CVD in Greenland. HighlightsThe Greenlandic Inuit have very high levels of whole blood mercury.Whole blood mercury was not associated with incident CVD in Greenland.CVD was associated with traditional risk factors such as HbA1c and physical activity.

Identification of novel high-impact recessively inherited type 2 diabetes risk variants in the Greenlandic population

Aims/hypothesisIn a recent study using a standard additive genetic model, we identified a TBC1D4 loss-of-function variant with a large recessive impact on risk of type 2 diabetes in Greenlanders. The aim of the current study was to identify additional genetic variation underlying type 2 diabetes using a recessive genetic model, thereby increasing the power to detect variants with recessive effects.MethodsWe investigated three cohorts of Greenlanders (B99, n = 1401; IHIT, n = 3115; and BBH, n = 547), which were genotyped using Illumina MetaboChip. Of the 4674 genotyped individuals passing quality control, 4648 had phenotype data available, and type 2 diabetes association analyses were performed for 317 individuals with type 2 diabetes and 2631 participants with normal glucose tolerance. Statistical association analyses were performed using a linear mixed model.ResultsUsing a recessive genetic model, we identified two novel loci associated with type 2 diabetes in Greenlanders, namely rs870992 in ITGA1 on chromosome 5 (OR 2.79, p = 1.8 × 10−8), and rs16993330 upstream of LARGE1 on chromosome 22 (OR 3.52, p = 1.3 × 10−7). The LARGE1 variant did not reach the conventional threshold for genome-wide significance (p < 5 × 10−8) but did withstand a study-wide Bonferroni-corrected significance threshold. Both variants were common in Greenlanders, with minor allele frequencies of 23% and 16%, respectively, and were estimated to have large recessive effects on risk of type 2 diabetes in Greenlanders, compared with additively inherited variants previously observed in European populations.Conclusions/interpretationWe demonstrate the value of using a recessive genetic model in a historically small and isolated population to identify genetic risk variants. Our findings give new insights into the genetic architecture of type 2 diabetes, and further support the existence of high-effect genetic risk factors of potential clinical relevance, particularly in isolated populations.Data availabilityThe Greenlandic MetaboChip-genotype data are available at European Genome-Phenome Archive (EGA; https://ega-archive.org/) under the accession EGAS00001002641.