Alaska Natives Study Research Articles

Sex differences in obesity prevalence and cardiometabolic factors among Western Alaska Native people

Background and aimsObesity is associated with increased risks of cardiovascular disease, type 2 diabetes, and other chronic diseases. Prevalence estimates for metabolic disorders are well documented in many populations, but Alaska Native groups are understudied. The Western Alaska Tribal Collaborative for Health Study combines data from three Alaska Native study cohorts to assess differences in obesity prevalence and associations with cardiometabolic risk factors by sex. Methods and resultsAnalyses were based upon a sample of 3985 adult Yup'ik and Inupiat participants with a mean age of 40 years. Prevalence of obesity and metabolic risk factors was assessed according to nationally recognized guidelines. Regression analysis was used to evaluate the association between obesity and cardiometabolic risk factors, including lipids, blood pressure and glucose. The prevalence of obesity (BMI ≥ 30) was significantly higher in women (40%) than men (20%). Only 18.6% of men had a waist circumference (WC) > 102 cm, while 58% of women had a WC > 88 cm (p < 0.001). Women had higher mean HDL-C and triglyceride levels compared to men, while systolic and diastolic blood pressure, LDL-C, and glucose means were higher in men than in women. In multivariate analyses, BMI and WC were significantly associated with all of the cardiometabolic risk factors, although these associations were more pronounced in men than women. ConclusionThe high prevalence of obesity and central adiposity among AN women is an important public health concern. Differences in associations between obesity and cardiometabolic risk factors by sex warrants further investigation to develop effective intervention programs.

CDKAL1 and HHEX are associated with type 2 diabetes‐related traits among Yup'ik people (在尤皮克人群中CDKAL1和HHEX与2型糖尿病相关特征有关)

AbstractBackgroundGenome‐wide association studies (GWAS) have identified single nucleotide polymorphisms (SNPs) associated with type 2 diabetes (T2D), mainly among individuals of European ancestry. In the present study, we examined the frequency of these SNPs and their association with T2D‐related traits in an Alaska Native study population with a historically low prevalence of T2D. We also investigated whether dietary characteristics that may protect against T2D, such as n‐3 polyunsaturated fatty acid (PUFA) intake, modify these associations.MethodsIn 1144 Yup'ik people, we examined 17 SNPs repeatedly identified in GWAS for individual and cumulative associations with T2D‐related traits. Cumulative associations were evaluated using a genetic risk score (GRS) calculated by summing risk alleles. Associations were tested for interactions with sex, body mass index (BMI), and n‐3 PUFA intake.ResultsThe rs7754840 SNP in CDKAL1 is significantly associated with HbA1c (P = 0.00091). The rs5015480 SNP near HHEX is significantly associated (in opposite direction to that in Europeans) with a combined fasting glucose (FG) and HbA1c measure (P = 0.00046) and with homeostatic model assessment of β‐cell function (HOMA‐B; P = 0.0014). The GRS is significantly associated with FG and combined FG and HbA1c only when the HHEX SNP is dropped from the GRS. Associations are not modified by BMI or n‐3 PUFA intake.ConclusionOur results highlight the potential importance of CDKAL1 and HHEX in glucose homeostasis in this Alaska Native population with a low prevalence of T2D, and suggest that these loci should be examined in greater detail in this population.

Lipoprotein subfractions and dietary intake of n-3 fatty acid: the Genetics of Coronary Artery Disease in Alaska Natives study

Few studies have compared lipoprotein composition with dietary intake. The lipoprotein subfraction profile was evaluated in relation to diet in Alaska Eskimos at high cardiovascular risk but with a low frequency of hyperlipidemia and high intake of n-3 (omega-3) fatty acids. A population-based sample (n = 1214) from the Norton Sound Region of Alaska underwent a physical examination and blood sampling. Analyses were from 977 individuals who did not have diabetes or use lipid-lowering medications and had complete dietary information (food-frequency questionnaire) and a lipoprotein subfraction profile (nuclear magnetic resonance spectroscopy). After adjustment for age, BMI, total energy intake, and percentage of energy from fat, the intake of n-3 fatty acids was significantly associated with fewer large VLDLs (P = 0.022 in women, P = 0.064 in men), a smaller VLDL size (P = 0.018 and P = 0.036), more large HDLs (P = 0.179 and P = 0.021), and a larger HDL size (P = 0.004 and P = 0.001). After adjustment for carbohydrate and sugar intakes, large VLDLs (P = 0.042 and 0.018) and VLDL size (P = 0.011 and 0.025) remained negatively associated with n-3 fatty acid intake in women and men, and large HDLs (P = 0.067 and 0.005) and HDL size (P = 0.001 in both) remained positively associated with n-3 fatty acid intake in women and men. In addition, large LDLs (P = 0.040 and P = 0.025) were positively associated in both sexes, and LDL size (P = 0.006) showed a positive association in women. There were no significant relations with total LDL particles in either model. Dietary n-3 fatty acids, independent of the reciprocal changes in carbohydrate and sugar intakes, are associated with an overall favorable lipoprotein profile in terms of cardiovascular risk. Because there are no relations with total LDL particles, the benefit may be related to cardiovascular processes other than atherosclerosis.

Albuminuria among Alaska Natives – Findings from the Genetics of Coronary Artery Disease in Alaska Natives (GOCADAN) Study

Background: The prevalence and associated risk factors for albuminuria and low-grade albuminuria in Alaska Natives is not known. Methods: Cross-sectional analysis of the Genetics of Coronary Artery Disease in Alaska Natives Study. We included 1,026 individuals, who represent 85% of the study participants for whom complete data were available. Risk factors examined were age, sex, education, diabetes, hypertension, obesity, lipids, C-reactive protein, angiotensin-converting enzyme inhibitor use, and smoking status. Urine albumin excretion was estimated by the albumin/creatinine ratio measured from a single random morning urine sample. Albuminuria was defined as an albumin/creatinine ratio of ≧30 mg/g. Low-grade albuminuria was defined as an albumin/creatinine ratio of 10 to <30 mg/g. Results: The mean age was 42 years and over half were female. Diabetes prevalence was low at 3% and the prevalence of hypertension was 20%. The prevalence of albuminuria was 6%; the prevalence of low-grade albuminuria was 12%. Individuals with diabetes or hypertension were 3 times more likely to have albuminuria than those without these conditions [odd ratios: diabetes 3.0 (1.2–7.9) and hypertension 3.0 (1.2–7.3)]. Conclusions: The burden of albuminuria is low. Comprehensive programs and policies are important given the rise in diabetes and hypertension among Alaska Natives.

Cardiovascular disease prevalence and its relation to risk factors in Alaska Eskimos

Background and aims Although Eskimos were thought to be protected from cardiovascular disease (CVD), state health data show a large proportion of deaths from CVD, despite traditional lifestyles and high omega-3 fatty acid intake. This article explores CVD prevalence and its relation to risk factors in Alaska Eskimos. Methods and results A population-based cohort of 499 Alaska Eskimos > age 45 from the Norton Sound region was examined in 2000–2004 for CVD and associated risk factors as part of the Genetics of Coronary Artery Disease in Alaska Natives study. CVD and atherosclerosis were evaluated and adjudicated using standardized methods. Average age was 58 years; diabetes prevalence was low and high-density lipoprotein cholesterol (HDL-C) concentrations were high, but a large proportion smoked and had high pathogen burden. CVD was higher in men (12.6%) than in women (5.3%) (prevalence ratio 2.4, CI 1.3–4.4). Rates of stroke (6.1% in men, 1.8% in women) were similar to those for coronary heart disease (CHD) (6.1% men, 2.5% women). MI prevalence was low in both genders (1.9% and 0.7%). CVD was higher in men and in those >60 years. Hypertension, diabetes, high LDL-C, high apoB, and low HDL-C were all strong correlates (<.002) and albuminuria and CRP were also correlated with CVD ( p < .05) after adjustment for age and gender. Carotid atherosclerosis was correlated with CVD ( p = .0079) independent of other risk factors. Conclusion These data show high CHD and stroke prevalence in Alaska Eskimos, despite low average LDL-C and high HDL-C. Hypertension and high LDL-C were independent correlates; identifying these risk factors early and treating to target is recommended.

Consumption of omega-3 fatty acids is not associated with a reduction in carotid atherosclerosis: The Genetics of Coronary Artery Disease in Alaska Natives study

Objective This study was designed to evaluate the relation between omega-3 fatty acid (FA) consumption and atherosclerosis. Background The hypothesis that omega-3 FAs protect against atherosclerosis has not been tested with objective measures of atherosclerosis. Methods A population-based sample of 1131 Alaskan Eskimos of age ≥18 underwent ultrasound assessment of carotid atherosclerosis. Those of age >35 ( N = 686) were included in the analysis. Diet was assessed by a food frequency questionnaire. Intimal–medial thickness (IMT) of the far wall of the distal common carotid arteries and plaque score (number of segments containing plaque) were assessed. Results Mean consumption of total omega-3 FAs was 4.76 g/day in those without and 5.07 g/day in those with plaque. In models adjusting for relevant risk factors, presence and extent of plaque were unrelated to intake of C20–22 omega-3 FAs or total omega-3 FAs. In contrast, the odds of plaque rose significantly with quartiles of palmitic ( p = 0.02) and stearic acid intake ( p = 0.04). The extent of plaque (or plaque score) was also associated with a higher percentage intake of palmitic acid ( p = 0.01). IMT was negatively associated with grams of C20–22 omega-3 FAs ( p = 0.05), total omega-3 ( p = 0.05), palmitate ( p = 0.03), and stearate ( p = 0.03) consumed. Conclusions Dietary intake of omega-3 FAs in a moderate-to-high range does not appear to be associated with reduced plaque, but is negatively associated with IMT. The presence and extent of carotid atherosclerosis among Eskimos is higher with increasing consumption of saturated FAs.

Common set of genes regulates low‐density lipoprotein size and obesity‐related factors in Alaskan Eskimos: Results from the GOCADAN Study

Increasing incidence of cardiovascular disease in traditionally low-risk Alaskan Eskimos is a cause for concern. The purpose of this study was to examine the genetic and environmental correlations of low-density lipoprotein (LDL) subfractions with obesity-related factors in Alaskan Eskimos, using data from the first 954 participants of the Genetics of Coronary Artery Disease in Alaska Natives Study. Estimates of genetic and environmental influence were calculated using a maximum likelihood variance component method implemented in SOLAR. Mean values of weight, body mass index (BMI), and waist were 73.4 +/- 0.5 kg, 27.6 +/- 0.2 kg/m2, and 88.0 +/- 0.4 cm, respectively. LDL, and its small (LDL1), medium (LDL2), and large (LDL3) subfractions, had mean values of 115.8 +/- 1.2 mg/dl, 8.3 +/- 0.4 mg/dl, 19.6 +/- 0.8 mg/dl, and 71.5 +/- 1.5 mg/dl, respectively. Bivariate analysis displayed significant genetic correlations between LDL subfractions and obesity-related factors: LDL1 with BMI (rhoG = 0.67, P < 0.05), waist (rhoG = 0.80, P < 0.001), and subscapular and tricep skinfolds (rhoG = 0.93, P < 0.005, and rhoG = 0.78, P < 0.05, respectively); LDL2 with BMI (rhoG = 0.52, P < 0.05), waist (rhoG = 0.46, P < 0.05), and tricep skinfold (rhoG = 0.60, P < 0.05); and mean LDL size with BMI (rhoG = -0.36), waist (rhoG = -0.42,), and subscapular and tricep skinfolds (rhoG = -0.44 and -0.43, respectively) (P < 0.005). These results show that a common set of genes is influencing LDL size and obesity-related factors in Alaskan Eskimos.

Alcohol Problems in Alaska Natives: Lessons from the Inuit

In this Alaska Native study, cultural "insiders" analyzed problems associated with increased alcohol availability, factors which have reduced alcohol-related problems, and ideas for improving treatment in an Inuit community. Participants described frequent binging, blackouts, family violence, suicide, loss of child custody, and feelings of intergenerational grief. Helpful existing treatment approaches include alcohol ordinances, inpatient treatment programs, twelve-step groups, and religious involvement. Participants urged the development of family treatment approaches which integrate Inuit customs and values.