Life events as predictors of unsustainable working life trajectories from a life course perspective

Background

The association between family-related life events (e.g., getting married or having children) and unsustainable working life in terms of unemployment, sickness absence and disability pension (SA/DP) are rarely studied from a life-course perspective although having public health importance. We investigated trajectories of unsustainable working life, and the associations between change in family-related life events and unsustainable working life trajectories by controlling for familial factors.

Methods

This is a prospective cohort study of 37,867 Swedish twins aged between 20-40 years on 31st December 1994. Data on trajectories of annual unemployment, SA/DP, and a combined measure of unsustainable working life months was collected from the Swedish national registers. The trajectories over a 23-year period were analysed by group-based trajectory modelling. Associations of change in family-related life events with trajectory groups in the whole sample were estimated by multinomial logistic regression and in discordant twin pairs (n = 4,647 pairs) with conditional models.

Results

Most participants had no or low levels of unemployment, SA/DP or combined unsustainable working life during 1994-2016. Individuals who were stably married or changed from being single living without children to married living with children had a decreased risk of unsustainable working life compared to individuals with stable family-related life events. The risk of unsustainable working life months over time was higher among individuals who changed from married to single status regardless of having children (range of HRs:1.31-4.44).

Conclusions

Family-related life events such as maintaining the relationship or getting married and having children decreases the risk of unsustainable working life while divorce is a risk factor for unsustainable working life. From a public health perspective, actions to support family formation or life would consequently promote a sustainable working life.

Key messages

• Unsustainable working life was less likely among married and among those who changed from single living without children to married with children compared to those with stable family life events.

• Individuals who changed from being married to divorced status had an increased risk of unsustainable working life over time and therefore being potentially an important group for public health.

Accuracy of self-reported anthropometric measures — Findings from the Finnish Twin Study

Objective:

To determine the accuracy of self-reported height, weight, body mass index (BMI) and waist circumference (WC) compared to the measured values, and to assess the similarity between self-reported and measured values within dizygotic (DZ) and monozygotic (MZ) twin pairs.

Methods:

The data on self-reported and measured height, weight and WC values as well as measured hip circumference (HC) were collected from 444 twin individuals (53–67 years old, 60% women). Accuracies between self-reported and measured values were assessed by Pearson’s correlation coefficients, Cohen’s kappa coefficients and Bland-Altman 95% limits of agreement. Intra-class correlation was used in within-pair analyses.

Results:

The correlations between self-reported and measured values were high for all variables (r = 0.86–0.98), although the agreement assessed by Bland-Altman 95% limits had relatively wide variation. The degree of overestimating height was similar in both sexes, whereas women tended to underestimate and men overestimate their weight. Cohen’s kappa coefficients between self-reported and measured BMI categories were high: 0.71 in men and 0.70 in women. Further, the mean self-reported WC was less than the mean measured WC (difference in men 2.5 cm and women 2.6 cm). The within-pair correlations indicated a tendency of MZ co-twins to report anthropometric measures more similarly than DZ co-twins.

Conclusions:

Self-reported anthropometric measures are reasonably accurate indicators for obesity in large cohort studies. However, the possibility of more similar reporting among MZ pairs should be taken into account in twin studies exploring the heritability of different phenotypes.

Associations between birth size and later height from infancy through adulthood: An individual based pooled analysis of 28 twin cohorts participating in the CODATwins project

BACKGROUND

There is evidence that birth size is positively associated with height in later life, but it remains unclear whether this is explained by genetic factors or the intrauterine environment.

AIM

To analyze the associations of birth weight, length and ponderal index with height from infancy through adulthood within mono- and dizygotic twin pairs, which provides insights into the role of genetic and environmental individual-specific factors.

METHODS

This study is based on the data from 28 twin cohorts in 17 countries. The pooled data included 41,852 complete twin pairs (55% monozygotic and 45% same-sex dizygotic) with information on birth weight and a total of 112,409 paired height measurements at ages ranging from 1 to 69 years. Birth length was available for 19,881 complete twin pairs, with a total of 72,692 paired height measurements. The association between birth size and later height was analyzed at both the individual and within-pair level by linear regression analyses.

RESULTS

Within twin pairs, regression coefficients showed that a 1-kg increase in birth weight and a 1-cm increase in birth length were associated with 1.14-4.25 cm and 0.18-0.90 cm taller height, respectively. The magnitude of the associations was generally greater within dizygotic than within monozygotic twin pairs, and this difference between zygosities was more pronounced for birth length.

CONCLUSION

Both genetic and individual-specific environmental factors play a role in the association between birth size and later height from infancy to adulthood, with a larger role for genetics in the association with birth length than with birth weight.

Genetic predisposition to obesity, restrained eating and changes in body weight: a population-based prospective study

OBJECTIVES

There is no consensus on whether cognitive control over food intake (that is, restrained eating) is helpful, merely ineffective or actually harmful in weight management. We examined the interplay between genetic risk of obesity, restrained eating and changes in body weight and size.

METHODS

Participants were Finnish aged 25-74 years who attended the DIetary, Lifestyle and Genetic determinants of Obesity and Metabolic syndrome study at baseline in 2007 and follow-up in 2014. At baseline (n=5024), height, weight and waist circumference (WC) were measured in a health examination and participants self-reported their weight at age 20 years. At follow-up (n=3735), height, weight and WC were based on measured or self-reported information. We calculated 7-year change in body mass index (BMI) and WC and annual weight change from age 20 years to baseline. Three-Factor Eating Questionnaire-R18 was used to assess restrained eating. Genetic risk of obesity was assessed by calculating a polygenic risk score of 97 known BMI-related loci.

RESULTS

Cross-lagged autoregressive models indicated that baseline restrained eating was unrelated to 7-year change in BMI (β=0.00; 95% confidence interval (CI)=-0.01, 0.02). Instead, higher baseline BMI predicted greater 7-year increases in restrained eating (β=0.08; 95% CI=0.05, 0.11). Similar results were obtained with WC. Polygenic risk score correlated positively with restrained eating and obesity indicators in both study phases, but it did not predict 7-year change in BMI or WC. However, individuals with higher genetic risk of obesity tended to gain more weight from age 20 years to baseline, and this association was more pronounced in unrestrained eaters than in restrained eaters (P=0.038 for interaction).

CONCLUSIONS

Our results suggest that restrained eating is a marker for previous weight gain rather than a factor that leads to future weight gain in middle-aged adults. Genetic influences on weight gain from early to middle adulthood may vary according to restrained eating, but this finding needs to be replicated in future studies.

Heritability of the Number of Teeth in Middle-Aged and Older Danish Twins

Tooth loss is a common health concern in older adults. We aimed to estimate the relative contributions of genetic and environmental factors to the variation in the number of teeth in middle-aged and older populations using a population-based cohort of Danish twins. The study included 5,269 Danish middle-aged or older twins who provided data on the number of teeth at baseline by structured interviews. The data were analyzed using univariate liability threshold modeling, stratified by sex and age, to estimate familial risk of tooth loss as well as estimates of heritability. In the whole cohorts, 23% of participants were edentate and 53% had retained 20 or more teeth. A statistical model including additive genetic factors and environmental factors partly shared by co-twins and partly unique to each individual twin gave the best statistical fit for the number of teeth in both age categories as well as in men and women. Overall, additive genetic factors explained 36% (95% confidence interval [CI]: 23% to 49%), common environmental factors 20% (95% CI: 9% to 31%), and unique environmental factors 44% (95% CI: 40% to 48%) of the total variation of the number of teeth. This study indicates that a substantial part of the variation in tooth loss is explained by genetic as well as environmental factors shared by co-twins. Our results implied that family background importantly affects tooth loss in both the middle-aged and the older populations. Family history is thus an important factor to take into account in dental health care.

Genetic architecture of motives for leisure-time physical activity: a twin study

The aim of this study was to estimate the contribution of genetic and environmental influences on motives for engaging in leisure-time physical activity. The participants were obtained from the FinnTwin16 study. A modified version of the Recreational Exercise Motivation Measure was used to assess the motives for leisure-time physical activity in 2542 twin individuals (mean age of 34.1 years). Linear structural equation modeling was used to investigate the genetic and environmental influences on motive dimensions. The highest heritability estimates were found for the motive dimensions of "enjoyment" [men 33% (95% CI 23-43%), women 53% (95% CI 45-60%)] and "affiliation" [men 39% (95% CI 0.28-0.49%), women 35% (95% CI 0.25-0.43%)]. The lowest heritability estimates were found for others' expectations [men 13% (95% CI 0.04-0.25%), women 15% (95% CI 0.07-0.24%)]. Unique environmental influences explained the remaining variances, which ranged from 47% to 87%. The heritability estimates for summary variables of intrinsic and extrinsic motives were 36% and 32% for men and 40% and 24% for women, respectively. In conclusion, genetic factors contribute to motives for leisure-time physical activity. However, the genetic effects are, at most, moderate, implying the greater relative role of environmental factors.

The effects of parental education on exercise behavior in childhood and youth: a study in Dutch and Finnish twins

Twin studies have estimated the relative contribution of genes and the environment to variance in exercise behavior and it is known that parental education positively affects exercise levels. This study investigates the role of parental education as a potential modifier of variance in exercise behavior from age 7 to 18 years. The study is based on large datasets from the Netherlands Twin Register (NTR: N = 24 874 twins; surveys around the ages of 7, 10, 12, 14, 16 and 18 years) and two Finnish twin cohorts (FinnTwin12: N = 4399; 12, 14 and 17 years; FinnTwin16: N = 4648; 16, 17 and 18 years). Regular participation in moderate-to-vigorous exercise activities during leisure time was assessed by survey. Parental education was dichotomized ("both parents with a low education" vs "at least one parent with a high education"). The mean in exercise behavior tended to be higher and the variance tended to be lower in children of high educated parents. Evidence for gene-by-environment interaction was weak. To develop successful interventions that specifically target children of low educated parents, the mechanisms causing the mean and variance differences between the two groups should be better understood.

Early-stage breast cancer is not associated with the risk of marital dissolution in a large prospective study of women

Background:

As breast cancer and its treatment are likely to interfere with traditional expectations of womanhood, it may affect marital stability.

Methods:

The risk of marital dissolution was analysed with respect to diagnosis of early-stage (T1–4N0–3M0) breast cancer in a cohort of 134 435 married Finnish women followed for a median of 17.0 married years. Age, socioeconomic status, education, number of children, duration of marriage and earlier marriages were taken into account and the effects of surgery, chemotherapy, radiotherapy and endocrine therapy were analysed separately.

Results:

Women with a diagnosis of early-stage breast cancer did not show increase in marital dissolution (hazard ratio=0.96, 95% confidence interval=0.79–1.17). Neither the type of surgical procedure nor any of the oncologic treatments was associated with an increase in the risk of divorce.

Conclusions:

Any evidence of excess risk of marital breakdown after the diagnosis of early-stage breast cancer and its treatment was not demonstrated.

Modifiable environmental influences on body mass index shared by young adult brothers

OBJECTIVES

Twin and adoption studies suggest that family environment has little, if any, influence on body mass index (BMI) in adulthood. We investigated the hypothesis that the differences in the years of birth between siblings influence their similarity in BMI at comparable ages, which would give evidence for a possibly modifiable influence of the environment shared by family members.

METHODS

Swedish full-brother pairs (N=261 712) born between 1951 and 1983 were measured for BMI in conscription examination at 16-26 years (median: 18.2 years) of age and were divided into quartiles by the difference between their birth-years (< 2.25 years, 2.25-3.33 years, 3.34-5.08 years and >5.08 years). Furthermore, 1961 dizygotic twin brother pairs from the same population representing brothers born at the same time were included. In addition, the log BMI of the younger brother was modeled as a linear function of the log BMI of the older brother. Subsequently, the significance of the interaction between birth-year difference and the BMI of the older brother was tested.

RESULTS

Intraclass correlation for BMI in dizygotic twin pairs was higher (0.431, 95% confidence interval (CI) 0.394-0.466) than the correlation for full-brothers in the first quartile of birth-year difference (0.376, CI 0.342-0.408). Among full-brothers, the BMI correlation decreased from 0.376 (CI 0.342-0.408) [corrected] in the first quartile to 0.338 (CI 0.331-0.345) in the last quartile. The regression analysis showed a statistically significant decrease in correlation with increasing birth-year difference (P<0.001).

CONCLUSION

The influence on BMI in young men of the environment shared by dizygotic twin brothers is greater than between non-twin full-brothers, indicating important influences of concomitant exposure to the same early life environment before and/or after birth. Among non-twin siblings there is a slight possibly modifiable influence as evidenced by declining correlations by increasing distance in years of birth.

Association and causal relationship of midlife obesity and related metabolic disorders with old age cognition

OBJECTIVE

Epidemiological studies suggest a relationship between midlife metabolism and old age cognition. We examined the effect of midlife BMI and related metabolic conditions on old age cognitive performance and whether there was evidence from direct causal pathways behind these associations in a large sample of Finnish twins.

DESIGN

Midlife variables of 2606 twin individuals were based on postal questionnaires and registry records. Old age cognitive status was measured by using a validated telephone interview.

RESULTS

Midlife BMI, cardiovascular disease, hypertension and diabetes were each associated with old age cognition when adjusted for sex, education, birth year and age at the interview. Similarly, overweight increased the risk for categories of mild impairment of cognitive function and likely dementia. Cardiovascular disease diminished the mean cognitive score also among discordant twin pairs (β-estimate=1.10, p-value= 0.012). Weight gain more than 1.7 kg/m(2) and loss more than 2 kg/m(2) within an average of 5.6 years were associated with lower cognitive performance independently of BMI. An additive genetic correlation explained the association between BMI and old age cognition (r(A)=-0.12, 95% CI -0.21; -0.03), but adjustment for education led to loss of significance (r(A)=-0.06, 95% CI -0.16; 0.03).

CONCLUSIONS

Midlife metabolic diseases, especially diabetes, are independently associated with impaired cognition in old age. Even a more subtle weight change than suggested previously was associated with lower old age cognition. There was evidence from direct causal pathway between cardiovascular disease and old age cognition, while the correlation between midlife BMI and old age cognition was explained mostly by genetic factors.

Leisure-time physical activity and type 2 diabetes during a 28 year follow-up in twins

AIMS/HYPOTHESIS

The study aimed to investigate whether baseline physical activity protects against the occurrence of type 2 diabetes during a 28 year follow-up, after controlling for childhood environment and genetic predisposition.

METHODS

At baseline in 1975 same-sex twin pairs born in Finland before 1958 were sent a questionnaire including questions on physical activity. The participants (20,487 individuals, including 8,182 complete twin pairs) were divided into quintiles by leisure-time physical activity metabolic equivalent (MET) index (MET h/day). Type 2 diabetes was determined from nationwide registers for the follow-up period (1 January 1976-31 December 2004). Individual and pairwise Cox proportional hazard models were used.

RESULTS

During follow-up, 1,082 type 2 diabetes cases were observed. Among all individuals, participants in MET quintiles (Q) III-V had significantly decreased risk for type 2 diabetes compared with sedentary individuals (QI). The pairwise analysis on pairs discordant for physical activity showed that participants in MET QII to V had significantly lower hazard ratios (0.61, 0.59, 0.61, 0.61) compared with sedentary participants. These findings from the pairwise analysis persisted after adjusting for BMI. In the pairwise analysis, the BMI-adjusted hazard ratio for type 2 diabetes was lower for physically active members of twin pairs (combined QII-V) than for inactive co-twins (HR 0.54; 95% CI 0.37-0.78). Similar results were obtained for both dizygotic and monozygotic pairs, as well as for the subgroup of twin pairs defined as free of co-morbidities in 1981 (HR 0.36; 95% CI 0.17-0.76).

CONCLUSIONS/INTERPRETATION

Leisure-time physical activity protects from type 2 diabetes after taking familial and genetic effects into account.

Evidence that BMI and type 2 diabetes share only a minor fraction of genetic variance: a follow-up study of 23,585 monozygotic and dizygotic twins from the Finnish Twin Cohort Study

AIMS/HYPOTHESIS

We investigated whether BMI predicts type 2 diabetes in twins and to what extent that is explained by common genetic factors.

METHODS

This was a population-based twin cohort study. Monozygotic (n = 4,076) and dizygotic (n = 9,109) non-diabetic twin pairs born before 1958 answered a questionnaire in 1975, from which BMI was obtained. Information on incident cases of diabetes was obtained by linkage to nationwide registers until 2005.

RESULTS

Altogether, 1,332 twins (6.3% of men, 5.1% of women) developed type 2 diabetes. The HR for type 2 diabetes increased monotonically with a mean of 1.22 (95% CI 1.20-1.24) per BMI unit and of 1.97 (95% CI 1.87-2.08) per SD of BMI. The HRs for lean, overweight, obese and morbidly obese participants were 0.59, 2.96, 6.80 and 13.64 as compared with normal weight participants. Model heritability estimates for bivariate variance due to an additive genetic component and non-shared environmental component were 75% (men) and 71% (women) for BMI, and 73% and 64%, respectively for type 2 diabetes. The correlations between genetic variance components (r (g)) indicated that one fifth of the covariance of BMI and type 2 diabetes was due to shared genetic influences. Although the mean monozygotic concordance for type 2 diabetes was approximately twice the dizygotic one, age of onset of diabetes within twin pair members varied greatly, irrespective of zygosity.

CONCLUSIONS/INTERPRETATION

A 28-year follow-up of adult Finnish twins showed that despite high trait heritability estimates, only a fraction of covariation in BMI and incident type 2 diabetes was of genetic origin.

Multicenter dizygotic twin cohort study confirms two linkage susceptibility loci for body mass index at 3q29 and 7q36 and identifies three further potential novel loci

OBJECTIVE

To identify common loci and potential genetic variants affecting body mass index (BMI, kg m(-2)) in study populations originating from Europe.

DESIGN

We combined genome-wide linkage scans of six cohorts from Australia, Denmark, Finland, the Netherlands, Sweden and the United Kingdom with an approximately 10-cM microsatellite marker map. Variance components linkage analysis was carried out with age, sex and country of origin as covariates.

SUBJECTS

The GenomEUtwin consortium consists of twin cohorts from eight countries (Australia, Denmark, the Netherlands, Finland, Italy, Norway, Sweden and the United Kingdom) with a total data collection of more than 500,000 monozygotic and dizygotic (DZ) twin pairs. Variance due to early-life events and the environment is reduced within twin pairs, which makes DZ pairs highly valuable for linkage studies of complex traits. This study totaled 4401 European-originated twin families (10,535 individuals) from six countries (Australia, Denmark, the Netherlands, Finland, Sweden and the United Kingdom).

RESULTS

We found suggestive evidence for a quantitative trait locus on 3q29 and 7q36 in the combined sample of DZ twins (multipoint logarithm of odds score (MLOD) 2.6 and 2.4, respectively). Two individual cohorts showed strong evidence independently for three additional loci: 16q23 (MLOD=3.7) and 2p24 (MLOD=3.4) in the Dutch cohort and 20q13 (MLOD=3.2) in the Finnish cohort.

CONCLUSION

Linkage analysis of the combined data in this large twin cohort study provided evidence for suggestive linkage to BMI. In addition, two cohorts independently provided significant evidence of linkage to three new loci. The results of our study suggest a smaller environmental variance between DZ twins than full siblings, with a corresponding increase in heritability for BMI as well as an increase in linkage signal in well-replicated regions. The results are consistent with the possibility of locus heterogeneity for some genomic regions, and indicate a lack of major common quantitative trait locus variants affecting BMI in European populations.

Physical activity reduces the influence of genetic effects on BMI and waist circumference: a study in young adult twins

OBJECTIVE

Both obesity and exercise behavior are influenced by genetic and environmental factors. However, whether obesity and physical inactivity share the same genetic vs environmental etiology has rarely been studied. We therefore analyzed these complex relationships, and also examined whether physical activity modifies the degree of genetic influence on body mass index (BMI) and waist circumference (WC).

METHODS

The FinnTwin16 Study is a population-based, longitudinal study of five consecutive birth cohorts (1975-1979) of Finnish twins. Data on height, weight, WC and physical activity of 4343 subjects at the average age of 25 (range, 22-27 years) years were obtained by a questionnaire and self-measurement of WC. Quantitative genetic analyses based on linear structural equations were carried out by the Mx statistical package. The modifying effect of physical activity on genetic and environmental influences was analyzed using gene-environment interaction models.

RESULTS

The overall heritability estimates were 79% in males and 78% in females for BMI, 56 and 71% for WC and 55 and 54% for physical activity, respectively. There was an inverse relationship between physical activity and WC in males (r = -0.12) and females (r=-0.18), and between physical activity and BMI in females (r = -0.12). Physical activity significantly modified the heritability of BMI and WC, with a high level of physical activity decreasing the additive genetic component in BMI and WC.

CONCLUSIONS

Physically active subjects were leaner than sedentary ones, and physical activity reduced the influence of genetic factors to develop high BMI and WC. This suggests that the individuals at greatest genetic risk for obesity would benefit the most from physical activity.

Genetic influences on the difference in variability of height, weight and body mass index between Caucasian and East Asian adolescent twins

OBJECTIVE

Twin studies are useful for investigating the causes of trait variation between as well as within a population. The goals of the present study were two-fold: First, we aimed to compare the total phenotypic, genetic and environmental variances of height, weight and BMI between Caucasians and East Asians using twins. Secondly, we intended to estimate the extent to which genetic and environmental factors contribute to differences in variability of height, weight and BMI between Caucasians and East Asians.

DESIGN

Height and weight data from 3735 Caucasian and 1584 East Asian twin pairs (age: 13-15 years) from Australia, China, Finland, Japan, the Netherlands, South Korea, Taiwan and the United States were used for analyses. Maximum likelihood twin correlations and variance components model-fitting analyses were conducted to fulfill the goals of the present study.

RESULTS

The absolute genetic variances for height, weight and BMI were consistently greater in Caucasians than in East Asians with corresponding differences in total variances for all three body measures. In all 80 to 100% of the differences in total variances of height, weight and BMI between the two population groups were associated with genetic differences.

CONCLUSION

Height, weight and BMI were more variable in Caucasian than in East Asian adolescents. Genetic variances for these three body measures were also larger in Caucasians than in East Asians. Variance components model-fitting analyses indicated that genetic factors contributed to the difference in variability of height, weight and BMI between the two population groups. Association studies for these body measures should take account of our findings of differences in genetic variances between the two population groups.

Genetic and environmental factors in relative weight from birth to age 18: the Swedish young male twins study

OBJECTIVES

To investigate the contributions of genetic and environmental factors to the development of relative weight during the growth period.

DESIGN

Longitudinal twin study.

SUBJECTS

Two-hundred and thirty-one monozygotic and 144 dizygotic complete male twin pairs born between 1973 and 1979 were measured annually from birth to 18 years of age.

RESULTS

Body mass index (BMI, kg/m(2)) at age 18 correlated with BMI at age 1 (r=0.32, 95% confidence intervals (CI) 0.21-0.42), and this correlation increased steadily up to age 17 (r=0.91, 95% CI 0.89-0.93). Major part (81-95%) of these trait correlations was attributable to correlate additive genetic factors, but also unique environmental correlations were present during the whole-growth period. The correlation between ponderal index (kg/m(3)) at birth and BMI at age 18 was small (r=0.09, 95% CI 0.02-0.15) and totally because of correlated unique environmental factors.

CONCLUSIONS

Our results suggest persistent genetic regulation of BMI from age 1 to 18. However, environmental factors, not shared by siblings, also affected the correlations of BMI. A small specific environmental correlation was found between ponderal index at birth and BMI at age 18, which may reflect the effect of neonatal environmental factors on adult BMI. A challenge to the future research is to identify chromosome regions and specific genes regulating the development of BMI as well as environmental factors affecting BMI through the growth period independently or interacting with genetic factors.

Negative life events and stability of sense of coherence: A five-year follow-up study of Finnish women and men

A strong sense of coherence (SOC) is found to be associated with good mental health. This study investigated (1) whether negative life events affect level of SOC, (2) whether initial level of SOC modifies the effect of negative life events on SOC, and (3) whether stability of SOC differs between genders. The data were derived from the 15-year Health and Social Support study (N= 17,271). Ordinary linear regression analysis was used. Negative life events decreased the level of SOC among both genders irrespective of the timing of the event. The more recent the life event, the lower the SOC. A strong SOC in 1998 did not protect SOC from declining during follow-up. Specific gender differences were not discovered. SOC was related to negative changes in people's environment. Initially strong SOC was not more stable than initially mediocre or weak SOC. Men and women reacted quite similarly to negative life events.

Coffee consumption, serum gamma-glutamyltransferase and risk of type II diabetes

OBJECTIVES

To study the joint association of coffee consumption and serum gamma-glutamyltransferase (GGT) levels on the risk of developing type II diabetes.

DESIGN, SETTING AND SUBJECTS

A total of 21,826 Finnish men and women who were 35-74 years of age and without any history of diabetes at baseline (years 1982, 1987, 1992 and 1997) were included in the present analyses. They were prospectively followed up for onset of type II diabetes (n=862 cases), death or until the end of the year 2002. Coffee consumption, serum GGT and other study parameters were determined at baseline using standardized measurements. Analyses were stratified by the serum GGT level classified into two classes using the 75th sex-specific percentiles as the cut point.

RESULTS

Coffee consumption was significantly and inversely associated with incident diabetes among both men and women. Serum GGT modified the association between coffee consumption and incident diabetes. Subjects in the high category of coffee consumption with the GGT level > or = 75th percentile showed a significant inverse association for women, and for both sexes combined. The association was not significant in subjects with the GGT level < or = 75th percentile. There was a significant interaction effect of GGT and coffee consumption on risk of type II diabetes in data of women (P=0.05) and in both sexes combined (P=0.02).

CONCLUSIONS

Habitual coffee consumption is associated with lower incidence of type II diabetes particularly in those with higher baseline serum GGT levels.

Genetic contributions to the association between height and intelligence: Evidence from Dutch twin data from childhood to middle age

A positive association between intelligence (IQ) and height has been reported previously. It is generally assumed that this association reflects the effect of childhood environment on IQ, but there is still little research supporting directly this hypothesis. We studied the association between height and IQ in 209 Dutch twin pairs at the ages of 5, 7, 10 and 12 years, 208 twin pairs at 16 and 18 years of age and 567 twin pairs and their siblings in adulthood. The heritability of height was high in all cohorts and across all ages (a2 = 0.93 - 0.96). In adulthood, heritability was also high for full-scale IQ (FSIQ: a2 = 0.83-0.84) and somewhat lower for verbal IQ (VIQ: a2 = 0.66-0.84). In early childhood, the heritability was lower, and common environmental factors had a substantial effect on FSIQ and VIQ. A positive association of height and IQ was found in early childhood and adolescence. In adulthood, a correlation was found between height and FSIQ in young adulthood and between height and VIQ in middle age. All correlations could be ascribed to genetic factors influencing both height and IQ. Thus, these results show that the association between height and IQ should not be directly regarded as evidence for childhood living conditions affecting IQ, but the effect of genetic factors affecting independently or interacting with environmental factors should be considered as well.

Socio-economic status and abdominal obesity among Finnish adults from 1992 to 2002

OBJECTIVE

To examine 10-year changes in waist circumference (WC) and identify socio-economic groups having higher WC than expected by their body mass index (BMI).

DESIGN

Population based cross-sectional surveys carried out in four regions of Finland in 1992, 1997 and 2002.

SUBJECTS

A total of 9026 women and 8173 men, aged 25-64 years.

MEASUREMENTS

Waist circumference, BMI, socio-economic indicators (education, household income, employment status, marital status) and health behaviors (smoking, alcohol use, physical activity).

RESULTS

In 2002, women had about 2.7 cm and men about 1.0 cm higher WC than subjects 10 years previously. Waist circumference increased more than BMI among women, especially among unemployed women. Higher WC among non-employed women was not explained by socio-economic indicators or health behaviors. Among men, smaller WC was associated with lower socio-economic status. However, associations partly disappeared after adjustment for health behaviors including physical activity at work.

CONCLUSION

Socio-economic patterning of WC is divergent and gender-specific. More attention should be paid to increasing waistlines among women.

Associations of SF-36 mental health functioning and work and family related factors with intentions to retire early among employees

OBJECTIVE

To examine the associations of mental health functioning (SF-36) and work and family related psychosocial factors with intentions to retire early.

METHODS

Cross sectional survey data (n = 5037) from the Helsinki Health Study occupational cohort in 2001 and 2002 were used. Intentions to retire early were inquired with a question: "Have you considered retiring before normal retirement age?" Mental health functioning was measured by the Short Form 36 (SF-36) mental component summary (MCS). Work and family related psychosocial factors included job demands and job control, procedural and relational justice, conflicts between work and family, and social network size. Multinomial regression models were used to analyse the data.

RESULTS

Poor mental health functioning, unfavourable psychosocial working conditions, and conflicts between work and family were individually related to intentions to retire early. After adjustments for all work and family related factors the odds ratio for low mental health functioning was halved (from OR = 6.05 to 3.67), but nevertheless the association between poor mental health functioning and strong intentions to retire early remained strong.

CONCLUSIONS

These findings highlight not only the importance of low mental health and unfavourable working conditions but also the simultaneous impact of conflicts between work and family to employees' intentions to retire early.

The effects of physical activity and body mass index on cardiovascular, cancer and all-cause mortality among 47 212 middle-aged Finnish men and women

OBJECTIVE

To examine the association of physical activity and body mass index (BMI), and their combined effect, with the risk of total, cardiovascular disease (CVD) and cancer mortality.

DESIGN

Prospective follow-up study.

SUBJECTS

In all, 22 528 men and 24 684 women aged 25-64 y at baseline having 7394 deaths during a mean follow-up of 17.7 y.

MEASUREMENT

A self-administered questionnaire data on smoking, socioeconomic factors, physical activity and medical history, together with measured height, weight, blood pressure and serum cholesterol using standardized protocol.

RESULT

Physically active subjects had significantly lower age-adjusted mortality from cardiovascular, cancer and all causes compared with sedentary ones. Further adjustment for smoking, systolic blood pressure, cholesterol, BMI, diabetes and education affected the results only slightly. Obese subjects (BMI> or =30 kg/m(2)) had significantly higher cardiovascular and total mortality than the normal weight (18.5< or =BMI<25 kg/m(2)) subjects. Part of increased mortality among obese subjects was mediated through obesity-related cardiovascular risk factors. BMI had an inverse association with cancer mortality among men and almost significant direct association among women. Total mortality was also increased among the lean (BMI<18.5 kg/m(2)) subjects. However, less than 0.3% of deaths were attributed to low body weight, whereas in men 5.5% and in women 17.7% of deaths were attributed to obesity.

CONCLUSION

Regular physical activity and normal weight are both important indicators for a decreased risk of mortality from all causes, CVD and cancer. Physical activity had a strong independent effect on mortality, whereas the effect of BMI was partly mediated through other obesity-related risk factors.

Intentional weight loss and smoking in young adults

OBJECTIVE

To investigate whether current smoking and lifetime snuff use are associated with a lifetime history of major (>/=5 kg) intentional weight loss in young adults, and to examine the dependence of this association on familial factors.

DESIGN

Cross-sectional population-based questionnaire survey of young adult Finnish twins participating in the fourth wave of the longitudinal FinnTwin-16-study in 2000-2002.

SUBJECTS

A total of 4521 young adult Finnish twins aged 23-27 y.

MEASUREMENTS

Questionnaire data on the number of intentional weight-loss episodes and on body mass index (BMI), cigarette smoking and snuff use, educational level, and number of subjects' own children.

RESULTS

Current daily smoking was strongly associated with a history of two or more intentional major weight-loss episodes (lost >/=5 kg twice or more lifetime) both in women odds ratio (OR 1.87; 95%; confidence interval (CI) 1.39-2.50) and in men (OR 2.00; 95% CI 1.37-2.90). Frequent lifetime snuff use was statistically significantly associated with recurrent intentional weight loss episodes in men (OR 1.51; 95% CI 1.08-2.13). Among the twin pairs discordant for daily smoking, the smoking twin was more likely than the nonsmoking co-twin to have recurrent intentional weight-loss episodes (OR 1.57; 95% CI 1.03-2.41). These episodes were also strongly associated with high BMI. Education was inversely related to recurrent intentional weight-loss episodes in men.

CONCLUSION

Tobacco use is strongly associated with a lifetime history of recurrent intentional major weight-loss episodes in early adulthood. This represents a major challenge to existing attitudes on smoking prevention and the promotion of healthful weight control.

Trends in obesity and energy supply in the WHO MONICA Project

OBJECTIVE

To examine the relationship between secular trends in energy supply and body mass index (BMI) among several countries.

DESIGN

Aggregate level analyses of annually reported country food data against anthropometric data collected in independent cross-sectional samples from 34 populations in 21 countries from the early 1980s to the mid-1990s.

SUBJECTS

Population randomly selected participants aged 35-64 y.

MEASUREMENTS

BMI data were obtained from the WHO MONICA Project. Food energy supply data were derived from the Food Balance Sheet of the Food and Agriculture Organization of the United Nations.

RESULTS

Mean BMI as well as the prevalence of overweight (BMI > or =25 kg/m2) increased in virtually all Western European countries, Australia, the USA, and China. Decreasing trends in BMI were seen in Central and Eastern European countries. Increasing trends in total energy supply per capita were found in most high-income countries and China while decreasing trends existed in Eastern European countries. Between country differences in temporal trends of total energy supply per capita explained 41% of the variation of trends in mean BMI; the effect was similar upon the prevalence of overweight and obesity. Trends in percent of energy supply from total fat per capita had a slight effect on the trends in mean BMI (+7% increment in R2) when the total energy supply per capita was adjusted for, while energy supply from total sweeteners per capita had no additional effect.

CONCLUSION

Increasing energy supply is closely associated with the increase of overweight and obesity in western countries. This emphasizes the importance of dietary issues when coping with the obesity epidemic.

The association between thinness and socio-economic disadvantage, health indicators, and adverse health behaviour: a study of 28 000 Finnish men and women

OBJECTIVE

To examine how thinness is associated with indicators of socio-economic disadvantage, health-related behaviours, and health indicators including mortality.

DESIGN

Independent risk factor surveys carried out in four geographic areas in Finland in 1982, 1987, 1992, and 1997, with mortality follow-up to the end of the year 2001.

SUBJECTS

A total of 13 389 men and 14 770 women aged 25-64 y at baseline, and 2077 deaths during the follow-up when subjects who have died during the first 5 y were excluded.

METHODS

A self-administrative questionnaire data on socio-economic status, health behaviour, and perceived health, together with measured height, weight, and metabolic indicators using standardised protocol. Mortality data by Statistics Finland were linked to the baseline surveys.

RESULTS

Thin men (BMI</=20 kg/m(2)) were the socio-economically disadvantaged group engaged in adverse health behaviours. They also reported poorer perceived health despite having better metabolic indicators. Thin women reported more adverse behaviours than other women and had better metabolic profile than their obese counterparts. Thin subjects had higher mortality, but results become nonsignificant among men when first 5 y of follow-up were excluded, and nonsignificant among women when health behaviours were adjusted for.

CONCLUSION

Thinness is associated with good metabolic profile but increased mortality, explained partly by underlying diseases or adverse behaviours. Thinness in men is associated with socio-economic disadvantage.

Occupational, commuting, and leisure-time physical activity in relation to risk for Type 2 diabetes in middle-aged Finnish men and women

AIM/HYPOTHESIS

Leisure-time physical activity can reduce the risk of Type 2 diabetes, but the potential effect of different types of physical activity is still uncertain. This study is to examine the relationship of occupational, commuting and leisure-time physical activity with the incidence of Type 2 diabetes.

METHODS

We prospectively followed 6898 Finnish men and 7392 women of 35 to 64 years of age without a history of stroke, coronary heart disease, or diabetes at baseline. Hazards ratios of incidence of Type 2 diabetes were estimated by levels of occupational, commuting, and leisure-time physical activity.

RESULTS

During a mean follow-up of 12 years, there were 373 incident cases of Type 2 diabetes. In both men and women combined, the hazards ratios of diabetes associated with light, moderate and active work were 1.00, 0.70 and 0.74 (p=0.020 for trend) after adjustment for confounding factors (age, study year, sex, systolic blood pressure, smoking, education, the two other types of physical activity and BMI). The multivariate-adjusted hazards ratios of diabetes with none, 1 to 29, and more than 30 min of walking or cycling to and from work were 1.00, 0.96, and 0.64 (p=0.048 for trend). The multivariate-adjusted hazards ratios of diabetes for low, moderate, high levels of leisure-time physical activity were 1.00, 0.67, and 0.61 (p=0.001 for trend); after additional adjustment for BMI, the hazards ratio was no longer significant.

CONCLUSIONS/INTERPRETATION

Moderate and high occupational, commuting or leisure-time physical activity independently and significantly reduces risk of Type 2 diabetes among the middle-aged general population.

Body height, birth cohort and social background in Finland and Sweden

BACKGROUND

Poor childhood living conditions are associated with short stature. Before the Second World War Finland had much lower living standards than Sweden, but this gap had largely disappeared by the 1970s. Body height differences were examined by birth cohort, economic difficulties in childhood and adult socioeconomic position in Finland and Sweden.

METHODS

Two nationally representative data sets were used (n = 7,300 in Finland and n = 4,551 in Sweden). Three indicators of social background were included, i.e. economic difficulties in childhood, education and occupational class. The methods used were direct age-standardisation, index of dissimilarity and regression analysis.

RESULTS

In the cohort born in 1920-1929 body height was taller in Sweden (175.8 cm among men and 163.7 cm among women) than in Finland (173.9 and 161.2 cm respectively). Body height by birth cohort increased faster in Finland, with the result that, in the cohort born in 1960-1969, the gap between the countries had narrowed to 0.8 cm among men and 0.3 cm among women. Body height differences by social background were larger in Finland than in Sweden. Socioeconomic body height differences have remained largely stable over the birth cohorts in both countries.

CONCLUSIONS

The results suggest that differential economic development is partly seen in the narrowing of body height differences between Finland and Sweden. However, socioeconomic differences in body height have remained largely similar over the birth cohorts studied and between Finland and Sweden.

Sex differences in genetic and environmental factors contributing to body-height

Sex differences in the heritability of self-reported body-height in two Finnish twin cohorts were studied by using sex-limitation models. The first cohort was born in 1938-1949 (N = 4873 twin pairs) and the second in 1975-1979 (N = 2374 twin pairs). Body-height was greater in the younger cohort (difference of 3.1 cm for men and 2.9 cm for women). The heritability estimates were higher among men (h2 = 0.87 in the older cohort and h2 = 0.82 in the younger cohort) than women (h2 = 0.78 and h2 = 0.67, respectively). Sex-specific genetic factors were not statistically significant in either cohort, suggesting that the same genes contribute to variation in body height for both men and women. The stronger contribution of environmental factors to body-height among women questions the hypothesis that women are better buffered against environmental stress, at least for this phenotype.

Genetic and environmental contributions to the association between body height and educational attainment: a study of adult Finnish twins

The nature of the association between body height and educational attainment found in previous studies remains to be clarified. The aim of this study was to examine factors contributing to this association by using a large Finnish twin data set (8798 adult twin pairs) gathered by questionnaire in 1981. A bivariate twin analysis was used to determine whether the genetic and environmental factors behind body height and educational attainment correlate with each other. A high heritability was found for body height (h2 = 0.78 in men and h2 = 0.75 in women), and a moderate heritability for education (h2 = 0.47 and h2 = 0.43, respectively). Shared environmental effects were also important in body height (c2 = 0.12 in men and c2 = 0.11 in women) and education (c2 = 0.36 and c2 = 0.43, respectively). A high correlation (r(c) = 0.77 in men, r(c) = 0.58 in women) of shared environmental factors education and body height, and weaker correlations (r = 0.11 and r = 0.08, respectively) of unshared environmental factors were found. The correlation of genetic factors between these two characteristics was not statistically significant. The results suggest that the association between body height and education is due mainly to nongenetic family factors.

Understanding income inequalities in health among men and women in Britain and Finland

The aims of this study were to investigate whether the relationship between income and self-perceived health is similar for men and women in two contrasting welfare states, Britain and Finland; whether the relationship between income and health is accounted for by employment status, education, and occupational social class; and whether the association differs when using alternative ways of measuring income: gross individual and net household equivalent income. Among British and Finnish men, low household and low individual income were related to poor health, even after adjusting for employment status, education, and social class. The adjusted relationship between individual income and health was stronger for British than Finnish men. Among British and Finnish women, net household equivalent income was strongly related to health, but after adjusting for employment status, education, and social class this relationship became weaker for British women and practically disappeared for Finnish women. For British women the association between income and health differed strongly depending on the income measure used; gross individual income had almost no effect on health. These results indicate that the association between health and income has no threshold in the sense that only people in poverty have poorer health than others. In further studies of income and health, household equivalent income should be used as the principal measure of income with adjustments for employment status, and men and women should be studied separately.

Relative effect of genetic and environmental factors on body height: differences across birth cohorts among Finnish men and women

OBJECTIVES

This study examined the change in heritability of adult body height across birth cohorts in Finland.

METHODS

In 1981, cross-sectional questionnaires were completed by 10,968 twin pairs born before 1958. The effect of genetic factors was estimated via genetic modeling.

RESULTS

Heritability increased from the cohort born before 1929 (0.76, 95% confidence interval [CI] = 0.65, 0.88 in men; 0.66, 95% CI = 0.55, 0.77 in women) to that born in 1947 through 1957 (0.81, 95% CI = 0.73, 0.87 in men; 0.82, 95% CI = 0.75, 0.89 in women).

CONCLUSIONS

Heritability of height increased across Finnish birth cohorts born in the first half of this century and leveled off after World War II. Environmental factors, compared with genetic factors, appear to be more important among women than men.

Social background, adult body-height and health

STUDY OBJECTIVE

To study the socio-demographic determinants of body-height and the bearing of these determinants on the association between body-height and health among Finnish adults.

DATA AND METHOD

Cross-sectional population survey including questions on social background, body-height and health, and retrospective questions on childhood living conditions. The data derive from a representative Survey on Living Conditions collected by Statistics Finland in 1994. The response rate was 73%. Male and female respondents > or =20 years were included in the analysis (N = 8212). Statistical methods include regression analysis and logistic regression analysis.

RESULTS

Body-height was strongly associated with year of birth, region, childhood living conditions and education among adult men and women. Body-height was also associated with limiting long-standing illness and perceived health as below good. Tall men had the best health and short men the poorest health. Among women the association of body-height with health differed from men, as tall women showed high levels of limiting long-standing illness, notably musculo-skeletal diseases. Adjusting for the background variables weakened but did not abolish the association between poor health and short stature among men and women.

CONCLUSIONS

Short stature is associated with poor health among Finnish men and women. A non-linear association among women was found for musculo-skeletal diseases. The studied social background factors explained only little of the association between body-height and health.

Gender differences in illhealth in Finland: patterns, magnitude and change

The common wisdom about gender differences in illhealth has been encapsulated in the phrase "women are sicker, but men die quicker". Recently this wisdom has been increasingly questioned. The purpose of this study is first to analyse the patterns and magnitude of gender differences across various indicators of illhealth; second to examine changes over time in these differences and third to assess whether sociodemographic and socioeconomic, family status and social network determinants have any bearing on the differences. The data derive from nationally representative 1986 and 1994 Surveys on Living Conditions in Finland. Women showed poorer health for five out of eight indicators analysed; that is somatic symptoms, mental symptoms, disability among those 50 years or older, long-standing illness and limiting long-standing illness were more prevalent among women than men. Male excess was found for perceived health below good and extremely limiting long-standing illness among those 50 years or older. However, the male excess was statistically significant only for poor perceived health among those 50 years or older. Adjusting for a number of suggested determinants of health had a negligible effect on gender differences. Further analyses showed that gender differences in illhealth remained largely stable over the eight year study period which saw a steep increase of unemployment for both genders. Only in the case of mental and somatic symptoms have gender differences declined, with a simultaneous increase in the prevalence of such symptoms. Otherwise gender differences in illhealth turned out to be resistant to the deep labour market crisis over this relatively short period of time. Although women had poorer health than men for a number of health indicators, we also find gender equality and even male excess for some indicators. Furthermore, the results suggest that a male excess in illhealth is likely to be found with more severe domains of illhealth among elderly people.