Multifactorial analysis of changes in body mass index across the adult life course: a study with 65 years of follow-up.

BACKGROUND: Although the negative consequences on health of being obese are well known, most adults gain weight across the lifespan. The general increase in body mass index (BMI) is mainly considered to originate from behavioral and environmental changes; however, few studies have evaluated the influence of these factors on change in BMI in the presence of genetic risk. We aimed to study the influence of multifactorial causes of change in BMI, over 65 years. METHODS AND FINDINGS: Totally, 6130 participants from TwinGene, who had up to five assessments, and 536 from the Swedish Adoption/Twin Study of Aging, who had up to 12 assessments, ranging over 65 years were included. The influence of lifestyle factors, birth cohort, cardiometabolic diseases and an individual obesity genetic risk score (OGRS) based on 32 single nucleotide polymorphisms on change in BMI was evaluated with a growth model. For both sexes, BMI increased from early adulthood to age of 65 years, after which the increase leveled off; BMI declined after age of 80 years. A higher OGRS, birth after 1925 and cardiometabolic diseases were associated with higher average BMI and a steeper increase in BMI prior to 65 years of age. Among men, few factors were identified that influence BMI trajectories in late life, whereas for women type 2 diabetes mellitus and dementia were associated with a steeper decrease in BMI after the age of 65 years. CONCLUSIONS: There are two turning points in BMI in late adulthood, one at the age of 65 years and one at the age 80 years. Factors associated with an increase in BMI in midlife were not associated with an increase in BMI after the age of 65 years. These findings indicate that the causes and consequences of change in BMI differ across the lifespan. Current health recommendations need to be adjusted accordingly.

Midlife dietary patterns and mortality in the population-based study of Swedish twins.

BACKGROUND: We examined midlife dietary patterns in relation to (1) sociodemographic and health-related characteristics and (2) survival. METHODS: A two-step cluster analysis of a 12-item food questionnaire was used to derive dietary patterns in a cohort of 16 649 members of the Swedish Twin Registry, a prospective, population-based study of twins. The average age at baseline (1967) was 55.5 years; the follow-up for all-cause mortality extended until 2011 (26.8±12.35 years or 345,127 person-years) via death records. RESULTS: Four dietary patterns (classes) distinguishable by demographic and health characteristics emerged: Moderate Intake and Starch Diet (Class 1), Moderate Intake Diet with Low Flour-Based Foods (Class 2), Meat and Starch Diet (Class 3) and Low Meat Intake Diet (Class 4). Membership in Class 3 was associated with 7% increased risk of mortality compared with Class 2 independent of baseline age, cohort, sex and body mass index. These results were mostly explained by sociodemographic and lifestyle factors. When follow-up was restricted to those in the study for 20+ years, both Classes 1 and 3 conferred increased risk of mortality compared with Class 2, independent of covariates. Analyses conducted within twin pairs revealed similar results. CONCLUSIONS: Midlife diet over-represented by meat and starch-based foods may increase the risk of mortality, whereas the diet low in starch may be beneficial. These results appear to be independent of factors shared by twins, as well as at least partially a function of social and lifestyle factors, particularly marital status and smoking.

Waist-to-height ratio is the best indicator for undiagnosed type 2 diabetes.

AIMS: Early detection of diabetes is important for the prevention of diabetic complications. The best adiposity index for indicating Type 2 diabetes mellitus remains unclear. We aimed to identify the optimal adiposity measure among BMI, waist circumference, waist-hip ratio and waist-to-height ratio to indicate undiagnosed Type 2 diabetes and impaired fasting glucose in Chinese adults. METHODS: A total of 7567 participants aged 20-79 years were included in this study. Impaired fasting glucose was defined as a fasting plasma glucose level of 6.1-6.9 mmol/l in participants without diabetes. Undiagnosed Type 2 diabetes was identified as fasting plasma glucose ≥ 7.0 mmol/l when neither a history of diabetes nor use of hypoglycaemic drugs was present. Body weight, height, waist and hip circumferences were measured following standard procedures. Data were analysed using logistic regression and areas under the receiver operating characteristic curves. RESULTS: Of the 7567 participants, 536 were defined as having impaired fasting glucose and 690 were patients with Type 2 diabetes, including 290 (3.8%) persons with undiagnosed diabetes. In multivariate logistic regression, the odds ratios of waist-to-height ratio (≥ 0.5) were stronger than BMI (≥ 24 kg/m²), waist circumference (≥ 85 cm in men and ≥ 80 cm in women) and waist-hip ratio (≥ 0.85) for undiagnosed Type 2 diabetes and impaired fasting glucose. Among the four indices, waist-to-height ratio ≥ 0.5 showed the largest area under the receiver operating characteristic curve for diagnosing undiagnosed Type 2 diabetes (0.725, 95% CI 0.693-0.756) and impaired fasting glucose (0.662, 95% CI 0.638-0.687). CONCLUSIONS: By comparison with BMI, waist circumference and waist-hip ratio, waist-to-height ratio ≥ 0.5 may be the best indicator for undiagnosed Type 2 diabetes and impaired fasting glucose.

Relation of socio-economic status to impaired fasting glucose and Type 2 diabetes: findings based on a large population-based cross-sectional study in Tianjin, China.

AIMS: Studies on the relationship between socio-economic status and Type 2 diabetes mellitus in the Chinese population are sparse. We aimed to examine the relation of socio-economic status as represented by income, education and occupation to impaired fasting glucose, Type 2 diabetes, and the control of Type 2 diabetes in a large Chinese population. METHODS: This study included 7315 individuals who were aged 20-79 years and living in Tianjin, China. Impaired fasting glucose and Type 2 diabetes were ascertained according to the 1999 World Health Organization criteria. Data were analysed using multinomial and binary logistic regression, with adjustment for potential confounders. RESULT: Among all participants, 532 (7.3%) persons had impaired fasting glucose, 688 (9.4%) persons had Type 2 diabetes, including 288 (3.9%) previously undiagnosed Type 2 diabetes. In fully adjusted multinomial logistic regression, compared with higher income (≥ 2000 yuan, $243.3/month), lower income (< 1000 yuan, $121.70/month) showed odds ratios (95% confidence intervals) of 3.31 (2.48-4.41) for impaired fasting glucose, 4.50 (3.07-6.61) for undiagnosed Type 2 diabetes and 4.56 (3.20-6.48) for diagnosed Type 2 diabetes. These results remained significant in the analysis stratified by education and occupation. Furthermore, persons who were retired were more likely to have impaired fasting glucose [odds ratio 1.91 (1.40-2.45)], undiagnosed Type 2 diabetes [odds ratio 2.01) 1.40-2.89] and diagnosed Type 2 diabetes [odds ratio 3.02 (2.12-4.22)]. Among the patients with Type 2 diabetes previously diagnosed, lower education (less than senior high school), non-manual work and unemployment were related to worse glycaemic control (fasting blood glucose level > 8.5 mmol/l). CONCLUSIONS: Lower income and retirement are associated with increased odds of impaired fasting glucose and Type 2 diabetes in Tianjin, China. Education and occupation may play a role in glycaemic control among patients with Type 2 diabetes.

Body mass index across midlife and cognitive change in late life.

BACKGROUND: High midlife body mass index (BMI) has been linked to a greater risk of dementia in late life, but few have studied the effect of BMI across midlife on cognitive abilities and cognitive change in a dementia-free sample. METHODS: We investigated the association between BMI, measured twice across midlife (mean age 40 and 61 years, respectively), and cognitive change in four domains across two decades in the Swedish Adoption/Twin Study of Aging. RESULTS: Latent growth curve models fitted to data from 657 non-demented participants showed that persons who were overweight/obese in early midlife had significantly lower cognitive performance across domains in late life and significantly steeper decline in perceptual speed, adjusting for cardio-metabolic factors. Both underweight and overweight/obesity in late midlife were associated with lower cognitive abilities in late life. However, the association between underweight and low cognitive abilities did not remain significant when weight decline between early and late midlife was controlled for. CONCLUSION: There is a negative effect on cognitive abilities later in life related to being overweight/obese across midlife. Moreover, weight decline across midlife rather than low weight in late midlife per se was associated with low cognitive abilities. Weight patterns across midlife may be prodromal markers of late life cognitive health.

Overweight in midlife and risk of dementia: a 40-year follow-up study.

OBJECTIVE: This study examines whether overweight in midlife increases dementia risk later in life. METHODS: In 1963 body mass index was assessed in 1152 participants of The Swedish Twin Registry, at the age of 45-65 years. These participants were later screened for dementia in a prospective study with up to 40 years follow-up. A total of 312 participants were diagnosed with dementia. RESULTS: Logistic regression analyses adjusted for demographic factors, smoking and alcohol habits, indicated that men and women categorized as overweight in their midlife had an elevated risk of dementia (OR=1.59; 95% CI: 1.21-2.07, P=0.002), Alzheimer's disease (OR=1.71; 95% CI: 1.24-2.35, P=0.003), and vascular dementia (OR=1.55; 95% CI: 0.98-2.47, P=0.059). Further adjustments for diabetes and vascular diseases did not substantially affect the associations, except for vascular dementia (OR=1.36; 95% CI: 0.82-2.56, P=0.116), reflecting the significance of diabetes and vascular diseases in the etiology of vascular dementia. There was no significant interaction between overweight and APOE epsilon4 status, indicating that having both risk factors does not have a multiplicative effect with regard to dementia risk. CONCLUSIONS: This study gives further support to the notion that overweight in midlife increases later risk of dementia. The risk is increased for both Alzheimer's disease and vascular dementia, and follows the same pattern for men and women.