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.


OBJECTIVE
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.
Jartti
L
L
Department of Geriatric Medicine, University of Turku, Turku, Finland.
Rönnemaa
T
T
Raitakari
O T
OT
Hedlund
E
E
Hammar
N
N
Lassila
R
R
Marniemi
J
J
Koskenvuo
M
M
Kaprio
J
J
D000367:Age Factors; D015415:Biomarkers / Q000097:blood; D002339:Carotid Arteries / Q000000981:diagnostic imaging*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging / Q000453:epidemiology*; D004641:Emigration and Immigration; D004730:Endothelium, Vascular / Q000502:physiology; D005387:Finland / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012306:Risk; D012959:Socioeconomic Factors; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors; D017539:Tunica Intima / Q000000981:diagnostic imaging; D017540:Tunica Media / Q000000981:diagnostic imaging; D014427:Twins; D014463:Ultrasonography
D015415:Biomarkers