Job strain as a risk factor for clinical depression: systematic review and meta-analysis with additional individual participant data.

BACKGROUND: Adverse psychosocial working environments characterized by job strain (the combination of high demands and low control at work) are associated with an increased risk of depressive symptoms among employees, but evidence on clinically diagnosed depression is scarce. We examined job strain as a risk factor for clinical depression. METHOD: We identified published cohort studies from a systematic literature search in PubMed and PsycNET and obtained 14 cohort studies with unpublished individual-level data from the Individual-Participant-Data Meta-analysis in Working Populations (IPD-Work) Consortium. Summary estimates of the association were obtained using random-effects models. Individual-level data analyses were based on a pre-published study protocol. RESULTS: We included six published studies with a total of 27 461 individuals and 914 incident cases of clinical depression. From unpublished datasets we included 120 221 individuals and 982 first episodes of hospital-treated clinical depression. Job strain was associated with an increased risk of clinical depression in both published [relative risk (RR) = 1.77, 95% confidence interval (CI) 1.47-2.13] and unpublished datasets (RR = 1.27, 95% CI 1.04-1.55). Further individual participant analyses showed a similar association across sociodemographic subgroups and after excluding individuals with baseline somatic disease. The association was unchanged when excluding individuals with baseline depressive symptoms (RR = 1.25, 95% CI 0.94-1.65), but attenuated on adjustment for a continuous depressive symptoms score (RR = 1.03, 95% CI 0.81-1.32). CONCLUSIONS: Job strain may precipitate clinical depression among employees. Future intervention studies should test whether job strain is a modifiable risk factor for depression.

Voxel-based morphometry study on monozygotic twins discordant for Alzheimer's disease.

OBJECTIVES: We set to investigate the possible role of genes and environment in developing Alzheimer's disease (AD) in monozygotic twin pairs discordant for AD. METHODS: Three pairs of twins discordant for AD, who were enrolled in the Finnish Twin Cohort, were used in the study and compared with 13 controls. Gray matter changes were assessed with magnetic resonance images using voxel-based morphometry with statistical parametric mapping. RESULTS: In the affected twins, the peaks of volume loss were located bilaterally in the temporal (including the hippocampus), the frontal, and the parietal lobes, while in the unaffected siblings, the peaks were located in the frontal gyri and in the parietal lobule. Thus, in the unaffected twins, the pattern of volume loss overlaps with the neocortical but not with the medial temporal areas. DISCUSSION: These findings suggest that genetic factors more largely control neocortical regions, whereas environmental factors more strongly affect medial temporal regions.

Diffuse gastrointestinal bleeding and BK polyomavirus replication in a pediatric allogeneic haematopoietic stem cell transplant patient.

Patients undergoing haematopoietic stem cell transplantation (HSCT) are at high risk of severe gastrointestinal bleeding caused by infections, graft versus host disease, and disturbances in haemostasis. BK polyomavirus (BKPyV) is known to cause hemorrhagic cystitis, but there is also evidence of BKV shedding in stool and its association with gastrointestinal disease. We report putative association of BKPyV replication with high plasma viral loads in a pediatric HSCT patient developing hemorrhagic cystitis and severe gastrointestinal bleeding necessitating intensive care. The observation was based on chart review and analysis of BKPyV DNA loads in plasma and urine as well as retrospective BKPyV-specific IgM and IgG measurements in weekly samples until three months post-transplant. The gastrointestinal bleeding was observed after a >100-fold increase in the plasma BKPyV loads and the start of hemorrhagic cystitis. The BKPyV-specific antibody response indicated past infection prior to transplantation, but increasing IgG titers were seen following BKPyV replication. The gastrointestinal biopsies were taken at a late stage of the episode and were no longer informative of BK polyomavirus involvement. In conclusion, gastrointestinal complications with bleeding are a significant problem after allogeneic HSCT to which viral infections including BKPyV may contribute.

Job strain and the risk of severe asthma exacerbations: a meta-analysis of individual-participant data from 100 000 European men and women.

BACKGROUND: Many patients and healthcare professionals believe that work-related psychosocial stress, such as job strain, can make asthma worse, but this is not corroborated by empirical evidence. We investigated the associations between job strain and the incidence of severe asthma exacerbations in working-age European men and women. METHODS: We analysed individual-level data, collected between 1985 and 2010, from 102 175 working-age men and women in 11 prospective European studies. Job strain (a combination of high demands and low control at work) was self-reported at baseline. Incident severe asthma exacerbations were ascertained from national hospitalization and death registries. Associations between job strain and asthma exacerbations were modelled using Cox regression and the study-specific findings combined using random-effects meta-analyses. RESULTS: During a median follow-up of 10 years, 1 109 individuals experienced a severe asthma exacerbation (430 with asthma as the primary diagnostic code). In the age- and sex-adjusted analyses, job strain was associated with an increased risk of severe asthma exacerbations defined using the primary diagnostic code (hazard ratio, HR: 1.27, 95% confidence interval, CI: 1.00, 1.61). This association attenuated towards the null after adjustment for potential confounders (HR: 1.22, 95% CI: 0.96, 1.55). No association was observed in the analyses with asthma defined using any diagnostic code (HR: 1.01, 95% CI: 0.86, 1.19). CONCLUSIONS: Our findings suggest that job strain is probably not an important risk factor for severe asthma exacerbations leading to hospitalization or death.

Human parvoviruses B19, PARV4 and bocavirus in pediatric patients with allogeneic hematopoietic SCT.

Among the immunocompetent, infections with parvovirus B19 (B19V) and human bocavirus (HBoV) 1 range clinically from asymptomatic to severe, while following allogeneic hematopoietic SCT (HSCT) B19V can cause a persistent severe illness. The epidemiology and clinical impact of HBoV1 and the other emerging parvovirus 4 (PARV4) among immunocompromised patients have not been established. To determine the occurrence and clinical spectrum of B19V, PARV4 and HBoV1 infections, we performed a longitudinal molecular surveillance among 53 allogeneic HSCT recipients for pre- and post-HSCT DNAemias of these parvoviruses. Quantitative real-time PCR showed B19V DNA in sera of 16 (30%) patients, at mean levels of 4.6 × 10(3), 9.9 × 10(7), 1.1 × 10(10) and 1.6 × 10(2) B19V DNA copies/mL pre-HSCT (9/53), and at 1 (6/53), 2 (4/53) and 3 months (1/25) post HSCT, respectively. However, no clinical manifestation correlated with the presence of B19V viremia. All B19V sequences were of genotype 1. None of the sera investigated contained PARV4 or HBoV1 DNAs. Our data demonstrate B19V viremia to be frequent among pediatric allogeneic HSCT recipients, yet without apparent clinical correlates. PARV4 or HBoV1 viremias were not seen in these immunocompromised patients.

Self-reported life satisfaction and alcohol use: a 15-year follow-up of healthy adult twins.

AIMS: To study the bidirectional relationships between life satisfaction (LS) and alcohol use. METHODS: Health questionnaires were administered in 1975, 1981 and 1990 to a population-based sample of healthy Finnish twins aged 18-45 at baseline (n = 14,083). These included a LS scale and three indicators for adverse alcohol use: binge drinking, passing out and high consumption (women/men ≥400/800 g/month). In longitudinal analyses, logistic regression, pair-wise case-control analyses and growth models were applied. RESULTS: All alcohol indicators increased the age-adjusted risk of becoming dissatisfied regardless of study period [binge drinking odds ratio (OR)(1975-1990 )= 1.29; 95% confidence interval (CI) 1.12-1.50; high consumption OR(1975-1990 )= 1.60; 1.29-1.99 and passing out OR(1981-1990 )= 2.01; 1.57-2.57]. Also, the dissatisfied had an increased subsequent risk for adverse alcohol use. The risk for passing out due to drinking (OR(1975-1990 )= 1.50; 1.22-1.86) was increased regardless of study period, while high consumption (OR(1975-1981 )= 1.97; 1.40-2.77; OR(1981-1990 )= 2.48; 1.50-4.12) and binge drinking (OR(1975-1981 )= 1.37; 1.12-1.67) showed some variation by the study period. Predictions remained after multiple adjustments. Longitudinally, high consumption predicted dissatisfaction somewhat more strongly than vice versa. The change/levels within the whole range of LS and alcohol consumption were only slightly associated in the entire study population. CONCLUSION: Life dissatisfaction and adverse alcohol use reciprocally predict each other prospectively. The heavier the alcohol use the stronger the relationship.

Job strain in relation to body mass index: pooled analysis of 160 000 adults from 13 cohort studies.

BACKGROUND: Evidence of an association between job strain and obesity is inconsistent, mostly limited to small-scale studies, and does not distinguish between categories of underweight or obesity subclasses. OBJECTIVES: To examine the association between job strain and body mass index (BMI) in a large adult population. METHODS: We performed a pooled cross-sectional analysis based on individual-level data from 13 European studies resulting in a total of 161 746 participants (49% men, mean age, 43.7 years). Longitudinal analysis with a median follow-up of 4 years was possible for four cohort studies (n = 42 222). RESULTS: A total of 86 429 participants were of normal weight (BMI 18.5-24.9 kg m(-2) ), 2149 were underweight (BMI < 18.5 kg m(-2) ), 56 572 overweight (BMI 25.0-29.9 kg m(-2) ) and 13 523 class I (BMI 30-34.9 kg m(-2) ) and 3073 classes II/III (BMI ≥ 35 kg m(-2) ) obese. In addition, 27 010 (17%) participants reported job strain. In cross-sectional analyses, we found increased odds of job strain amongst underweight [odds ratio 1.12, 95% confidence interval (CI) 1.00-1.25], obese class I (odds ratio 1.07, 95% CI 1.02-1.12) and obese classes II/III participants (odds ratio 1.14, 95% CI 1.01-1.28) as compared with participants of normal weight. In longitudinal analysis, both weight gain and weight loss were related to the onset of job strain during follow-up. CONCLUSIONS: In an analysis of European data, we found both weight gain and weight loss to be associated with the onset of job strain, consistent with a 'U'-shaped cross-sectional association between job strain and BMI. These associations were relatively modest; therefore, it is unlikely that intervention to reduce job strain would be effective in combating obesity at a population level.

Early detection of Alzheimer disease: ¹¹C-PiB PET in twins discordant for cognitive impairment.

OBJECTIVE: The aim of this study was to investigate whether cognitively preserved monozygotic or dizygotic cotwins of persons with Alzheimer disease (AD) exhibit increased brain amyloid accumulation. METHODS: We performed a cross-sectional carbon-11 labeled 2-(4'-methylaminophenyl)-6-hydroxybenzothiazole ((11)C)-Pittsburgh compound B (PiB) PET study on 9 monozygotic and 8 dizygotic twin pairs discordant for cognitive impairment as well as on 9 healthy elderly control subjects. (11)C-PiB uptake was analyzed with Statistical Parametric Mapping and with region of interest analysis with the region-to-cerebellum ratio as a measure of tracer uptake. RESULTS: Cognitively preserved monozygotic cotwins of cognitively impaired probands had increased cortical (11)C-PiB uptake (117%-121% of control mean) in their temporal and parietal cortices and the posterior cingulate. Cognitively preserved dizygotic subjects did not differ from the controls. Further, the cognitively preserved monozygotic subjects showed similar (11)C-PiB uptake patterns as their cognitively impaired cotwins. The cognitively impaired subjects (monozygotic and dizygotic individuals combined) showed typical Alzheimer-like patterns of (11)C-PiB uptake. CONCLUSIONS: Genetic factors appear to influence the development of Alzheimer-like ß-amyloid plaque pathology. The dissociation between cognitive impairment and brain ß-amyloidosis in monozygotic twins implies that there may be important environmental/acquired factors that modulate the relationship between brain amyloidosis and neurodegeneration. AD may be detectable in high-risk individuals in its presymptomatic stage with (11)C-PiB PET, but clinical follow-up will be needed to confirm this.

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 (ß-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.

Evening types are more often current smokers and nicotine-dependent-a study of Finnish adult twins.

AIMS: To examine the association between diurnal type and smoking status and nicotine dependence (ND). DESIGN: A cohort study using random-effects model regressions for repeated longitudinal panel data was used to analyse smoking status by diurnal type. Regression analyses examined the association between diurnal type and ND. PARTICIPANTS: A total of 23, 289 same-sex adult twin individuals from Finnish Twin Cohort. Nicotine dependence was studied in a subsample of 676 twin individuals. MEASUREMENTS: Subjects were classified by self-report into four categories: morning type, somewhat morning type, somewhat evening type, evening type (in 1981). Smoking status was defined as current and ever smoking (in 1975, 1981 and 1990). ND was measured by DSM-IV and Fagerström Test for Nicotine Dependence (FTND) (during 2001-05). Findings Evening types of both genders were much more likely to be current (OR = 2.91, 95% CI 2.50, 3.38) and life-time smokers (OR = 2.67, 95% CI 2.96, 4.07) compared to morning types. Evening types were less likely to stop smoking. The risk of nicotine dependence assessed by DSM-IV criteria was higher among evening types (OR = 2.78, 95% CI 1.64, 4.72). Evening types scored 0.59 (95% CI 0.01, 1.17) points higher than morning types on the FTND. Adjustment for potential confounders did not change these associations. CONCLUSIONS: Being an evening type is associated independently with a higher risk of being a current smoker, being more highly dependent upon cigarettes and a lower likelihood of stopping smoking. Understanding the cause of these associations could elucidate the causes of tobacco addiction.

Smoking strongly predicts disability retirement due to COPD: the Finnish Twin Cohort Study.

No previous studies on the association of smoking behaviour with disability retirement due to register verified chronic obstructive pulmonary disease (COPD) exist. This 30-yr follow-up study examined how strongly aspects of cigarette smoking predict disability retirement due to COPD. The study population consisted of 24,043 adult Finnish twins (49.7% females) followed from 1975 to 2004. At baseline the participants had responded to a questionnaire. Information on retirement was obtained from the Finnish pension registers. Smoking strongly predicted disability retirement due to COPD. In comparison to never-smokers, age adjusted hazard ratio (HR) for current smokers was 22.0 (95% CI 10.0-48.5) and for smokers with ≥ 12 pack-yrs was 27.3 (95% CI 12.6-59.5). Similar estimates of risk were observed in within-pair analyses of twin pairs discordant for disability retirement due to COPD. Among discordant monozygotic pairs those with disability pension due to COPD were more often current smokers. The effect of early smoking onset (< 18 yrs) on the risk of disability retirement due to COPD remained after adjustment for the amount smoked (HR 1.70, 95% CI 1.08-2.68). Smoking strongly predicts disability retirement due to COPD. Preventive measures against disability retirement and other harmful consequences of tobacco smoking should receive greater emphasis.

Stressful life events and the onset of asthma.

The status of stressful life events as a risk factor for asthma is unclear and may be dependent on pre-existing allergic rhinitis. This study examined whether exposure to stressful life events predicted the onset of asthma in adults. This is a prospective, population-based cohort study of 16,881 males and females, aged 20-54 yrs and free of diagnosed asthma at the beginning of the follow-up (January 1, 2004). Data about stressful life events were gathered with a postal survey. The onset of asthma was ascertained through national registers until December 31, 2005. During the follow-up period, 192 incident cases of asthma were identified. High total exposure to stressful life events, as indicated by a cumulative severity score, predicted the onset of asthma (hazard ratio 1.96, 95% CI 1.22-3.13). This association was robust to adjustment for demographics, smoking and having a cat/dog at home and it was observed both among those with and without allergic rhinitis at baseline. Of the 10 most stressful life events, the illness of a family member, marital problems, divorce or separation and conflicts with a supervisor were associated with the onset of asthma. Our study suggests that stressful life events may increase the onset of asthma.

Bruxism is associated with nicotine dependence: a nationwide Finnish twin cohort study.

OBJECTIVES: To investigate the association of smoking with bruxism while controlling for genetic and environmental factors using a co-twin-control design. Especially, the role of nicotine dependence was studied in this context. METHODS: The material derives from the Finnish Twin Cohort consisting of 12,502 twin individuals who responded to a questionnaire in 1990 (response rate of 77%). All were born in 1930-1957, the mean age being 44 years. The questionnaire covered 103 multiple choice questions, 7 dealing with tobacco use and 22 with sleep and vigilance matters, including perceived bruxism. In addition, a subsample derived from the Nicotine Addiction Genetics Finland Study containing 445 twin individuals was studied. RESULTS: In age- and gender-controlled multinomial logistic regression, both monthly and rarely reported bruxism associated with both current cigarette smoking (odds ratio [OR] = 1.74 and 1.64) and former cigarette smoking (OR = 1.64 and 1.47). Weekly bruxism associated with current smoking (OR = 2.85). Current smokers smoking 20 or more cigarettes a day reported weekly bruxism more likely (OR = 1.61-1.97) than those smoking less. Among twin pairs (N = 142) in which one twin was a weekly bruxer and the cotwin a never bruxer, there were 13 monozygotic pairs in which one twin was a current smoker and the other twin was not. In all cases, the bruxer was the smoker (p = .0003). Nicotine dependence associated significantly with bruxism. CONCLUSIONS: Our twin study provides novel evidence for a possible causal link between tobacco use and bruxism among middle-aged adults. Nicotine dependence may be a significant predisposing factor for bruxism.

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.

Genetic contribution to the relationship between personality and depressive symptoms among older women.

BACKGROUND: Prior studies suggest that certain types of personality are at higher risk for developing depressive disorders. This study examined the relationship between old age depressive symptoms and two middle-age personality dimensions, neuroticism and extraversion. METHOD: The present study is part of the Finnish Twin Study on Aging, where altogether 409 female twins who had completed the Eysenck Personality Inventory at the age of 38-51 years were studied for depressive symptoms 28 years later using Center for the Epidemiologic Studies Depression Scale. Logistic regression analysis suitable for dependent data and univariate and Cholesky models for decomposing the genetic and environmental factor were used. RESULTS: Middle age extraversion protected from later depressive symptoms while neuroticism increased the risk. Twin modeling indicated that the association between neuroticism and depressive symptoms resulted from shared genetic risk factors common to both traits. However, a substantial proportion of the genetic vulnerability was specific to old age depressive symptoms and was not shared with neuroticism. Middle age extraversion had no genetic relationship with old age depressive symptoms. CONCLUSIONS: The relationship between middle age neuroticism and old age depressive symptoms is strong but only partly the result of genetic factors that predispose to both neuroticism and depressive symptoms. Extraversion, by contrast, has no genetic relationship with depressive symptoms experienced in old age.

Self-reported preclinical mobility limitation and fall history as predictors of future falls in older women: prospective cohort study.

UNLABELLED: We studied if self-reported preclinical mobility limitation, described as modification of task performance without perception of difficulty, predicts future falls in older women with and without fall history. Our results suggest that combined measure of self-reported preclinical mobility limitation and fall history may offer one possibility for inexpensive fall-risk evaluation in clinical practice. INTRODUCTION: We studied if self-reported preclinical mobility limitation predicts future falls in older women with and without fall history. METHODS: The study population consisted of 428 community-living 63-76-year-old women. At baseline, those who expressed no difficulty walking 2 km but reported that it took longer than before or that they did it less often were categorized as having preclinical mobility limitation. Those reporting difficulty in 2-km walk were categorized as having manifest mobility limitation. Fall history was recalled for previous 12 months and dichotomized. The incidence of future falls over 12 months was followed up with fall calendars. RESULTS: During the fall follow-up, a total of 440 falls were reported by 201 participants. Among those with fall history, women with preclinical mobility limitation had almost 4-fold (incidence rate ratios 3.77; 95% CI 1.02-13.92) and those with manifest mobility limitation almost 15-fold (14.66; 2.72-79.00) adjusted risk for future falls compared to those with no mobility limitation and no previous falls. Among women without fall history, preclinical and manifest mobility limitation did not predict future falls nor did fall history without mobility limitation. CONCLUSIONS: Already, early signs of mobility decline with history of falls increase the risk of further falls and should be considered as indications for fall prevention interventions.

Migration at early age from a high to a lower coronary heart disease risk country lowers the risk of subclinical atherosclerosis in middle-aged men.

BACKGROUND: Study of migrants offers a natural model to assess environmental risk of coronary heart disease (CHD) in countries differing in CHD occurrence. In Sweden, CHD risk has been markedly lower than in Finland from where a large migration occurred in the 1970s. OBJECTIVES: To study the structural and functional markers of subclinical atherosclerosis in twin pairs discordant for migration with the main focus on age at migration, length of residence and integration into Swedish society after migration from a high to a lower CHD risk country. METHODS: Carotid intima-media thickness (IMT) and brachial artery endothelial function (EF) were assessed with high-resolution ultrasound and a set of cardiovascular, socio-economic and psychosocial risk factors were estimated in 76 middle-aged male twin pairs discordant for migration from Finland to Sweden. RESULTS: Men who had migrated in adolescence had lower IMT values compared with their co-twins living in Finland (0.665 +/- 0.114 vs. 0.802 +/- 0.167 mm, P = 0.009). Also men who integrated well to Swedish society had lower (0.720 +/- 0.154 vs. 0.799 +/- 0.207 mm, P = 0.013) IMT values than their twin brothers living in Finland. Associations between IMT and migration age and between IMT and integration remained significant in multivariate analyses of several CHD risk factors. The intrapair difference in IMT was significantly associated with immigration age and integration (ANOVA, P = 0.0082), the difference being greatest among pairs where the brother living in Sweden had migrated at early age and integrated well to Swedish society. EF was better in men who had migrated to Sweden before the age of 21 years, but not later, compared with their co-twins in Finland (6.4 +/- 4.6% vs. 3.8 +/- 3.6%, P = 0.025). CONCLUSIONS: Migration at an early age and good integration are beneficial to vascular health associated with moving from a high to a lower CHD risk country, suggesting that an environment-sensitive period influences atherogenesis before adulthood.

Voxel-based analysis of cerebral glucose metabolism in mono- and dizygotic twins discordant for Alzheimer disease.

BACKGROUND: Sporadic Alzheimer disease (AD) is a multifactorial disease to which both genetic and environmental factors contribute. Therefore, twin pairs are useful in studying its pathogenesis and aetiology. Cerebral glucose metabolism has been found to be reduced in AD patients. METHODS: Cerebral glucose metabolism was studied in seven monozygotic (MZ) and nine same-sexed dizygotic (DZ) twin pairs discordant for AD using positron emission tomography. To obtain objective and explorative results concerning differences in glucose metabolism, the analysis was performed utilising modern voxel-based analysis methodology statistical parametric mapping and automated region-of-interest analysis. RESULTS: In the demented MZ and DZ co-twins, cerebral glucose metabolism was extensively reduced compared with controls. The non-demented MZ co-twins showed reduced metabolism in inferior frontal, lateral temporal, parietal and medial temporal cortices as well as in the thalamus, putamen and right amygdala. In contrast, no reductions were found in the non-demented DZ co-twins. The reduction found in the non-demented MZ co-twins may be an indicator of genetic susceptibility to AD.

Migration and differences in dietary habits-a cross sectional study of Finnish twins in Sweden.

OBJECTIVE: To compare dietary habits between Finnish twin migrants to Sweden and their co-twins always living in Finland, and to analyse how migration influenced food consumption patterns in the migrants. SUBJECTS/METHODS: Same-sexed twin pairs born in Finland below 75 years of age, with at least one twin migrating to Sweden (n=1083 pairs). Dietary habits were assessed by a food frequency questionnaire included in a comprehensive mailed questionnaire (response rate 71%). For 76 male twin pairs, information was also collected by a dietary history interview inquiring the habitual diet during the previous year. RESULTS: Migrant twins in Sweden had a lower intake of typical Finnish foods like dark bread and berries, and an increased consumption of fresh fruit compared with co-twins living in Finland. The migrants consumed less potatoes and more rice and pasta. Sweet pastries were consumed less often by the migrants and they also tended to more often cut out visible fat of meat and on the other hand add salt to dishes. Among men the migrants had a lower alcohol intake than their co-twins living in Finland. CONCLUSIONS: Migration from Finland to Sweden is associated with differences in the food pattern that reflect population differences in eating habits between the two countries. The differences include a reduced consumption of typical Finnish foods like dark bread and berries and are of bidirectional nature from the point of view of cardiovascular health.