We investigated whether BMI predicts type 2 diabetes in twins and to what extent that is explained by common genetic factors.
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.
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.
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.
To examine whether adolescent flexibility, endurance strength, and physical activity can predict the later occurrence of recurrent low back pain, tension neck, or knee injury.
In 1976, 520 men and 605 women participated in a sit and reach test (flexibility) and a 30 second sit up test (endurance strength). In 1976 and 2001 (aged 37 and 42 years) they completed a questionnaire. Lifetime occurrence and risk of self reported low back pain and self reported, physician diagnosed tension neck and knee injury were calculated for subjects divided into tertiles by baseline results of strength and flexibility tests.
Men from the highest baseline flexibility tertile were at lower risk of tension neck than those from the lowest tertile (odds ratio (OR) 0.51, 95% confidence interval (CI) 0.28 to 0.93). Women from the highest baseline endurance strength tertile were at lower risk of tension neck than those from the lowest tertile (OR 0.60, 95% CI 0.40 to 0.91). Men from the highest baseline endurance strength tertile were at higher risk of knee injury than those from the lowest tertile (OR 1.96, 95% CI 1.05 to 3.64). Men who at school age participated in physical activity were at lower risk of recurrent low back pain (OR 0.61; 95% CI 0.42 to 0.88) than those who did not.
Overall good flexibility in boys and good endurance strength in girls may contribute to a decreased risk of tension neck. High endurance strength in boys may indicate an increased risk of knee injury.
Cites: Spine (Phila Pa 1976). 1998 Jan 15;23(2):235-439474732
Cites: Med Sci Sports Exerc. 1997 Aug;29(8):1062-89268964
We have reported cross-sectional evidence that behavioral similarities of adult monozygotic (MZ) cotwins are associated with their age at initial separation and the frequency of their subsequent social interaction (Kaprio et al., 1987; Rose et al., 1988; Rose and Kaprio, 1988). Twins who separated early and twins in infrequent interaction were less alike. Data for those reports came from a 1981 survey of the Finnish Twin Cohort. The Finnish cohort had been surveyed in 1975 with a similar questionnaire, and we now report a longitudinal analysis of the 1975-1981 surveys. All cohabiting MZ cotwins, ages 18-25 at the 1975 baseline, were followed up in 1981, and pairwise similarities at baseline and follow-up were compared for three groups: MZ pairs that remained cohabiting, separated pairs in which the cotwins retained regular contact with one another, and separated cotwins whose social interactions at follow-up were infrequent. For alcohol consumption and EPI Neuroticism scores, relative similarities of the MZ cotwins at follow-up paralleled the relative frequencies of their social contact; baseline differences in resemblance for Extraversion scores preceded follow-up differences in social interaction. These findings clarify the directional nature of associations found in our cross-sectional data and provide new, more compelling evidence of effects of shared experience on sibling resemblance for some dimensions of adult behavior.
To study whether persistent leisure-time physical activity (PA) during adulthood predicts use of antidepressants later in life.
The Finnish Twin Cohort comprises same-sex twin pairs born before 1958, of whom 11 325 individuals answered PA questions in 1975, 1981 and 1990 at a mean age of 44 years (range 33-60). PA volume over 15-years was used as the predictor of subsequent use of antidepressants. Antidepressant use (measured as number of purchases) for 1995-2004 were collected from the Finnish Social Insurance Institution (KELA) prescription register. Conditional logistic regression was conducted to calculate odds ratios (OR) with 95% confidence intervals (CI) for the use of antidepressants in pairs discordant for PA (642, including 164 monozygotic (MZ) pairs).
Altogether 229 persons had used at least one prescribed antidepressant during the study period. Active co-twins had a lower risk (unadjusted OR 0.80, 95%CI 0.67-0.95) for using any amount of antidepressants than their inactive co-twins; trends being similar for DZ (0.80, 0.67-0.97) and MZ pairs (0.78, 0.51-1.17). The lowest odds ratio (0.51, 0.26-0.98) was seen among MZ pairs after adjusting for BMI, smoking and binge drinking. The point estimates were similar but non-significant for long-term antidepressant use (4+purchases equivalent to 12 months use).
Self-reported physical activity and low number of discordant MZ pairs.
Use of antidepressants was less common among physically active co-twins even when shared childhood experiences and genetic background were controlled for. Physical activity in midlife may therefore be important in preventing mild depression later in life.
This study examined the stability and change over time in genetic and environmental influences on walking ability among older women. Maximal walking speed over 10 m and 6-min walking endurance test were measured under standard conditions at baseline and 3 years later. At both times, 63 monozygotic (MZ) and 67 dizygotic (DZ) twin pairs were measured for walking speed and 58 MZ and 56 DZ pairs for walking endurance. Participants were twin sisters reared together and aged 63-75 years at baseline. Genetic and environmental influences were examined using longitudinal genetic modelling. The results showed that walking speed was preserved from baseline to follow-up. Genetic influences on walking speed were also similar at baseline (56%) and follow-up (60%). Walking endurance declined from baseline to follow-up, while genetic influences for walking endurance increased from baseline (40%) to follow-up (60%). Most of the genetic influences identified at baseline were also present at follow-up for walking speed (r(g)=0.72) and endurance (r(g)=0.71). In conclusion, among relatively healthy older women, genetic influences on walking speed and endurance were moderate at baseline, while at 3-year follow-up a moderate increment was observed in walking endurance. Newly expressed genetic influences were recognized at follow-up.
A population-based epidemiological study of the prevalence of headache in a sample of 24,682 adults was carried out in Finland. Enquiries were made concerning the frequency of headache, migraine and characteristics of headache attacks in a questionnaire survey in 1981. Headache was classified as migraine, and headache without migrainous features. Possible somatic causes of headache were excluded by record-linkage with three nation-wide medical registries. The prevalence of both headache types depended on age and gender. Among women the overall prevalence of migraine was 10.1% with a maximum of 11.5% in the 40-49 age group. The prevalence rate among men was 2.5% and the female/male gender ratio was 4.0. Women with migraine had an average of 52.5 headache occasions during a year and men with migraine 61 headache occasions per year. At the individual level, headache without migrainous features was least invalidating. There were only 16.5 headache occasions a year among women and 11.5 among men. However, from a population perspective headache without migrainous features accounted for 46.5% of all headache occasions among women and for 60.8% among men. Thus, from the public health view-point, studies of "non-clinical" headache, e.g. headache without migrainous features should be emphasized.
Intimal thickenings of the coronary arteries of newborn children are composed mainly of smooth muscle cell proliferations. To investigate whether thickening of the intima in infants is associated with a family history of coronary artery disease (CAD), we studied the relation of coronary death of grandparents to intimal thickening of 136 infants.
The length of internal elastic lamina of the artery and the areas of arterial layers in cross section were measured, and the arteries were transformed to idealized round circles. Intimal thickening was assessed as the degree of luminal narrowing (ratio of intimal area to the area on the luminal side of the arterial media). Among 136 infants, luminal narrowing varied between 0% and 58%. CAD deaths accounted for 108 of the total 281 deaths among the grandparents of the infants. Family history of CAD (defined as at least one CAD death among the four grandparents) was positive for 77 infants. Family history of CAD was significantly more common in the infants with luminal narrowing of both the left and right coronary arteries compared with the infants with no narrowing in at least one artery (odds ratio adjusted for sex, infection status, and age of infant, 5.69; 95% confidence interval, 1.46-22.2). After adjustment for sex and age, infants with both a positive family history and presence of infection had an increased degree of luminal narrowing compared with infants with a negative family history and no infection.
The association of coronary artery intimal thickening in infancy with family history of CAD suggests that intimal thickening is a morphological manifestation of predisposition to CAD.
The Finnish Twin Cohort study (27,776 individuals; all twins of the same sex born before 1958 and alive in 1967) detected 316 cases of epileptic seizures occurring in 310 twin pairs: 89 monozygotic pairs and 221 dizygotic pairs, including three concordant monozygotic pairs and three concordant dizygotic pairs. The ratio of the observed to expected number of concordant pairs for epileptic seizures was 5.48 (90% CL 1.5-14.2) in monozygotic and 2.12 (90% CL 0.6-5.5) in dizygotic pairs. The results suggest that 8% to 27% of the incidence of epileptic seizures is related to genetic variability. The study of environmental differences in discordant monozygotic pairs should provide insights into the etiology of this group of disorders.
Department of Health Sciences, University of Jyväskylä, Jyväskylä, Finland Keski-Suomen Magneettikuvaus, Jyväskylä, Finland Department of Medical Rehabilitation, Oulu University Hospital and Institute of Health Sciences, University of Oulu, Oulu, Finland Department of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland Department of Public Health and Institute of Molecular Medicine, University of Helsinki, Helsinki, Finland Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, Helsinki, Finland.
Exercise is thought to increase the diameter of the conduit arteries supplying the muscles involved. We studied the effects of a physically active vs inactive lifestyle on artery diameters in monozygotic (MZ) twin pairs discordant over 30 years for leisure-time physical activity habits. In a population-based co-twin control study design, six middle-aged (50-65 years) same-sex MZ twin pairs with long-term discordance for physical activity were comprehensively identified from the Finnish Twin Cohort (TWINACTIVE study). Discordance was initially defined in 1975 and the same co-twin remained significantly more active during the 32-year follow-up. The main outcomes were arterial lumen diameters measured from maximal intensity projections of contrast-enhanced MR angiography images. Paired differences between active and inactive co-twins were studied. Compared with inactive members, active members of MZ twin pairs had larger diameters for the distal aorta and iliac and femoral arteries (P0.2 for all comparisons) were found in the dimensions of the carotid arteries. Our genetically controlled study confirms that habitual physical activity during adulthood enlarges arteries in a site-specific manner.
BACKGROUND: The prevalence of asthma is rising and there are recent reports of increasing asthma rates among top level skiers and runners in the Nordic countries. METHODS: The lifetime occurrence of pulmonary diseases (asthma, chronic bronchitis, emphysema) and current bronchitis symptoms was compared in former elite male athletes (n = 1282) who represented Finland between 1920 and 1965 at least once in international competitions and controls (n = 777) who, at the age of 20, were classified as healthy and who responded to a questionnaire in 1985. The presence of disease and symptoms was identified from the questionnaire and, in the case of asthma, also from a nationwide reimbursable medication register. The death certificates of the subjects of our original cohort who died between 1936 and 1985 were also investigated to determine the cause of death. RESULTS: The occurrence of the pulmonary diseases was associated with age, smoking habits, occupational group, and a history of exposure to chemicals. After adjusting for these variables, athletes who participated in mixed sports (odds ratio (OR) 0.46, 95% confidence interval (CI) 0.23 to 0.92) and power sports (OR 0.43, 95% CI 0.21 to 0.87) had lower odds ratios for emphysema, and endurance sports athletes had a lower odds ratio for the presence of at least one pulmonary disease (OR 0.53, 95% CI 0.28 to 0.98) when compared with controls. Athletes also tended to have fewer reimbursable medications for asthma and fewer current symptoms for chronic bronchitis. Between 1936 and 1985 two controls but none of the athletes died of asthma. CONCLUSIONS: The lifetime occurrence of asthma or other pulmonary diseases is not increased in former elite athletes, and exercise alone, even in a cold environment, did not appear to increase the prevalence of asthma, at least up to the mid 1980s.