Infant and childhood growth and frailty in old age: the Helsinki Birth Cohort Study

Mendelian randomization shows causal effects of birth weight and childhood body mass index on the risk of frailty

Background

The association between birth weight and childhood body mass index (BMI) and frailty has been extensively studied, but it is currently unclear whether this relationship is causal.

Methods

We utilized a two-sample Mendelian randomization (MR) methodology to investigate the causal effects of birth weight and childhood BMI on the risk of frailty. Instrumental variables (p < 5E-08) strongly associated with own birth weight (N = 298,142 infants), offspring birth weight (N = 210,267 mothers), and childhood BMI (N = 39,620) were identified from large-scale genomic data from genome-wide association studies (GWAS). The frailty status was assessed using the frailty index, which was derived from comprehensive geriatric assessments of older adults within the UK Biobank and the TwinGene database (N = 175,226).

Results

Genetically predicted one standard deviation (SD) increase in own birth weight, but not offspring birth weight (maternal-specific), was linked to a decreased frailty index (β per SD increase = -0.068, 95%CI = -0.106 to -0.030, p = 3.92E-04). Conversely, genetically predicted one SD increase in childhood BMI was associated with an elevated frailty index (β per SD increase = 0.080, 95%CI = 0.046 to 0.114, p = 3.43E-06) with good statistical power (99.8%). The findings remained consistent across sensitivity analyses and showed no horizontal pleiotropy (p > 0.05).

Conclusion

This MR study provides evidence supporting a causal relationship between lower birth weight, higher childhood BMI, and an increased risk of frailty.

Understanding the Causes of Frailty Using a Life-Course Perspective: A Systematic Review

(1) Background: Few studies have examined risk factors of frailty during early life and mid-adulthood, which may be critical to prevent frailty and/or postpone it. The aim was to identify early life and adulthood risk factors associated with frailty. (2) Methods: A systematic review of cohort studies (of at least 10 years of follow-up), using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA). A risk of confounding score was created by the authors for risk of bias assessment. Three databases were searched from inception until 1 January 2023 (Web of Science, Embase, PubMed). Inclusion criteria were any cohort study that evaluated associations between any risk factor and frailty. (3) Results: Overall, a total of 5765 articles were identified, with 33 meeting the inclusion criteria. Of the included studies, only 16 were categorized as having a low risk of confounding due to pre-existing diseases. The long-term risk of frailty was lower among individuals who were normal weight, physically active, consumed fruits and vegetables regularly, and refrained from tobacco smoking, excessive alcohol intake, and regular consumption of sugar or artificially sweetened drinks. (4) Conclusions: Frailty in older adults might be prevented or postponed with behaviors related to ideal cardiovascular health.

Body Composition in Late Midlife as a Predictor of Accelerated Age-associated Deficit-accumulation From Late Midlife into Old Age: A Longitudinal Birth Cohort Study

BACKGROUND

Body mass index (BMI) may not be an optimal predictor of frailty as its constituents, lean and fat mass, may have opposite associations with frailty.

METHODS

A linear mixed model analysis was performed in the Helsinki Birth Cohort Study (n = 2 000) spanning from 57 to 84 years. A 39-item frailty index (FI) was calculated on three occasions over 17 years. Body composition in late midlife included BMI, percent body fat (%BF), waist-to-hip ratio (WHR), lean mass index (LMI), and fat mass index (FMI).

RESULTS

Mean FI levels increased by 0.28%/year among men and by 0.34%/year among women. Among women, per each kg/m2 higher BMI and each unit higher %BF the increases in FI levels per year were 0.013 percentage points (PP) steeper (95% CI = 0.004, 0.023) and 0.009 PP steeper (95% CI = 0.002, 0.016) from late midlife into old age. Among men, per each 0.1-unit greater WHR the increase in FI levels was 0.074 PP steeper per year (95% CI = -0.0004, 0.148). Cross-sectionally, greater FMI and LMI in late midlife were associated with higher FI levels but the direction of the association regarding LMI changed after adjustment for FMI. The categories "high FMI and high LMI" and "high FMI and low LMI" showed the highest FI levels relative to the category "low FMI and low LMI".

CONCLUSIONS

In late midlife, greater adiposity (%BF) among women and abdominal obesity (WHR) among men may predispose to higher levels of frailty from late midlife into old age. Greater lean mass alone may be protective of frailty, but not in the presence of high fat mass.

Trajectories of physical and mental functioning over 25 years before onset of frailty: results from the Whitehall II cohort study

BACKGROUND

Research on frailty, a major contributor to heterogeneity in health, is undertaken on older adults although the processes leading to frailty are likely to begin earlier in the life course. Using repeat data spanning 25 years, we examined changes in physical and mental functioning before the onset of frailty, defined using Fried's frailty phenotype (FFP).

METHODS

Functioning was measured using the Short-Form 36 General Health Survey (SF-36) on nine occasions from 1991 (age range 40-63 years) to 2015 (age range 63-85 years). The poorest of four FFP scores from 2002, 2007, 2012 and 2015 was used to classify participants as frail, pre-frail, or robust. We used linear mixed models with a backward timescale such that time 0 was the person-specific date of frailty classification for frail and pre-frail participants and the end of follow-up for robust participants. Analyses adjusted for socio-demographic factors, health behaviours, body mass index and multi-morbidity status were used to compare SF-36 physical (PCS) and mental (MCS) component summary scores over 25 years before time 0 as a function of FFP classification, with estimates extracted at time 0, -5, -10, -15, -20 and -25 years. We also used illness-death models to examine the prospective association between SF-36 component summary scores at age 50 and incident FFP-defined frailty.

RESULTS

Among 7044 participants of the Whitehall II cohort study included in the analysis [29% female, mean age 49.7 (SD = 6.0) at baseline in 1991], 2055 (29%) participants remained robust, and 4476 (64%) became pre-frail and 513 (7%) frail during follow-up. Frail compared with robust participants had lower SF-36 scores at t = -25 before onset of frailty with a difference of 3.4 [95% confidence interval (CI) 1.6, 5.1] in PCS and 1.8 (-0.2, 3.8) in MCS. At t = 0, the differences increased to 11.5 (10.5, 12.5) and 9.1 (8.0, 10.2), respectively. The differences in SF-36 between the robust and pre-frail groups, although smaller [at t = 0, 1.7 (1.2, 2.2) in PCS and 4.0 (3.4, 4.5) in MCS], were already observed 20 and 25 years, respectively, before the onset of pre-frailty. Prospective analyses showed that at age 50, scores in the bottom quartiles of PCS [hazard ratio (HR) compared with the top quartile = 2.39, 95% CI 1.85, 3.07] and MCS [HR = 1.49 (1.15, 1.93)] were associated with a higher risk of FFP-defined frailty at older ages.

CONCLUSIONS

Differences in trajectories of physical and mental functioning in individuals who developed physical frailty at older ages were observable 25 years before onset of FFP-defined frailty. These findings highlight the need for a life course approach in efforts to prevent frailty.

Physical capability in a rural birth cohort at the age of 52: association with early environmental, nutritional, and developmental factors

Introduction

Midlife physical capability (PC) is associated with developmental factors in the populations of economically developed countries. As far as we know, there is no information for rural populations of low- and middle-income countries. The aim of the study was to investigate the influence of pre- and postnatal factors on midlife objective measures of PC in a 1966–67 birth cohort from a Mexican rural community. The hypothesis was that adverse developmental conditions are associated with low midlife PC.

Methods

In 1966–67, a birth cohort of all children from a poor Mexican rural community was assembled. Data on family socioeconomic status (SES), parental health and nutritional status, birth weight, postnatal growth and feeding patterns were registered. In 2018, out of the 336 cohort members, 118 were living in the community, and eighty-two of them underwent a comprehensive clinical evaluation. The evaluation included grip strength, gait velocity and chair-stand PC tests. In multivariable linear models, PC tests were the dependent variables, and prenatal, birth and postnatal factors were the independent variables. Adjustment for confounding was made with adult anthropometric, body composition, clinical and ageing status variables.

Results

Independent of adult health status and other ageing indicators, lower PC was associated with family organization and SES, parental nutritional status, birth weight, infant postnatal growth velocity, and weaning time. These results indicate that adverse family and environmental conditions that are prevalent in poor rural communities are associated with low midlife PC.

Early life factors as predictors of age-associated deficit accumulation across 17 years from midlife into old age

BACKGROUND

Early life exposures have been associated with the risk of frailty in old age. We investigated whether early life exposures predict the level and rate of change in a frailty index (FI) from midlife into old age.

METHODS

A linear mixed model analysis was performed using data from three measurement occasions over 17 years in participants from the Helsinki Birth Cohort Study (n=2000) aged 57-84 years. A 41-item FI was calculated on each occasion. Information on birth size, maternal body mass index (BMI), growth in infancy and childhood, childhood socioeconomic status (SES), and early life stress (wartime separation from both parents), was obtained from registers and healthcare records.

RESULTS

At age 57 years the mean FI level was 0.186 and the FI levels increased by 0.34 percent/year from midlife into old age. Larger body size at birth associated with a slower increase in FI levels from midlife into old age. Per 1kg greater birth weight the increase in FI levels per year was -0.087 percentage points slower (95% CI=-0.163, -0.011; p=0.026). Higher maternal BMI was associated with a higher offspring FI level in midlife and a slower increase in FI levels into old age. Larger size, faster growth from infancy to childhood, and low SES in childhood were all associated with a lower FI level in midlife but not with its rate of change.

CONCLUSIONS

Early life factors seem to contribute to disparities in frailty from midlife into old age. Early life factors may identify groups that could benefit from frailty prevention, optimally initiated early in life.

The degree of frailty as a translational measure of health in aging

Frailty is a multiply determined, age-related state of increased risk for adverse health outcomes. We review how the degree of frailty conditions the development of late-life diseases and modifies their expression. The risks for frailty range from subcellular damage to social determinants. These risks are often synergistic-circumstances that favor damage also make repair less likely. We explore how age-related damage and decline in repair result in cellular and molecular deficits that scale up to tissue, organ and system levels, where they are jointly expressed as frailty. The degree of frailty can help to explain the distinction between carrying damage and expressing its usual clinical manifestations. Studying people-and animals-who live with frailty, including them in clinical trials and measuring the impact of the degree of frailty are ways to better understand the diseases of old age and to establish best practices for the care of older adults.

Association Between Life-Course Obesity and Frailty in Older Adults: Findings in the GAZEL Cohort

OBJECTIVE

This study aimed to assess the relationship between weight history during adulthood and frailty in late life in men and women participating in the GAZEL (GAZ and ELectricité) cohort.

METHODS

This cohort study included 8,751 men and 3,033 women (aged 61 to 76 years) followed up since 1989. Modified Fried's frailty criteria (weakness, fatigue, unintentional weight loss, low physical activity, and impaired mobility) were assessed in 2015. Reported BMI was determined each year to characterize: obesity status in 2015, obesity duration over the 1990 to 2015 period, and trajectories of BMI. Associations between frailty and weight history were assessed using multinomial regression.

RESULTS

In 2015, 12% of men had obesity, 1.8% severe obesity, and 0.4% morbid obesity; for women, these percentages were 11%, 2.2%, and 0.8%, respectively. Individuals with obesity were more likely to be frail than those with normal BMI and the risk of frailty increased with each additional year of obesity (adjusted odds ratio 1.04 [1.00-1.08] for men and 1.07 [1.02-1.13] for women). Trajectories of BMI revealed that both long-term obesity and onset of obesity in late adulthood were associated with frailty.

CONCLUSIONS

Current and past obesity appear to be important determinants of frailty. Early weight management may be beneficial in old age.