Comparative Studies of Icelandic People Living in Canada and Iceland
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201 COMPARATIVE STUDIES OF ICELANDIC PEOPLE LIVING IN CANADA AND ICELAND J6hann Axelsson, Jens 6.P. Palsson, Gudrun Petursd6ttir, Nikulas Sigfusson and Antony B. Way Department of Physiology, Faculty of Medicine, University of Iceland, Institute of Anthropology, University of Iceland, The Heart Preventive Clinic, Reykjavik, Iceland, and Texas Tech University, Health Sciences Center, Texas, U.S.A. Icelandic populations provide unique opportu carried out. nities for epidemiological and anthropological The first phase of the study took place in research, because of their genetic homogeneity and Canada in 1975, 1977 and 1978, when Piilsson the availability of detailed geneological inform continued his demographic, genealogical and ation concerning them. anthropological research on Vestur-lslendingar. In This paper describes a comparative study of all, nearly 700 adults and 300 school children were Icelanders and people of Icelandic descent living in investigated (20, 21, 22). Canada, commonly called Vestur-lslendingar. It The second phase, a field study of Icelanders aims mainly at assessing the relative importance of inhabiting the Fljotsdalur District ( Fljotsdals genetic and environmental factors in chronic herad) in Eastern leeland (Fig. 1), wa conducted disease, emphasizing cardiovascular risk factors. in 1979and1980. Asimilarstudyofthe Icelandic In Canada we investigate descendatns of Ice population in Canada is planned in 1982-83. landers who emigrated in the late 19th century and the beginning of this century. Both mono- and BACKGROUND polyfactorial traits will be used to assess the gene Iceland is an island bordering on the arctic circle. tic relations of these people to those in Iceland. It has an area of 103.000 km2, and its population An interdisciplinary comparative study will be is close to 230.000, half of whom live in the 6tf' tef' Fig. 1. Iceland with Flj6tsdalsherad encircled. 202 capital city, Reykjavik, and surrounding area. computerized health and medical records have According to medieval sources, Iceland was been kept in recent decades by the District Health settled between 870 and 930 A.O., mainly from Centre (Heilsugaeslustodin) in Egilsstadir (26). Norway, but also from Scotland and Ireland (1, Fljotsdalh~rad is a farming area with a total 12). There is no evidence of subsequent migration population of about 2.700. The town of Egillsta to the country. dir (population ca. 1.200), located within the Several methods have been applied to estimate district, is a centre of commerce and light in the Irish and British genetic contribution to the dustry. Some of the climatic characteristics of Icelandic population, with varying results (9, 10, Fljotsdalsherad, as measured by the metero 15, 17, 18, 19, 27, 28, 29). On the basis of sero logical stations at Hallormsstadur and Egilsstadir logical studies (9), Thompson came to the con ( 11 ), are indicated in Fig. 2. It can be noticed that clusion that Icelanders are almost entirely of the period 1920.£6 was relatively warm in com »eeltic» origin (28). Palsson (15, 18, 19) has point parison with the last decade. ed out, that a considerable selective genetic differ It is assumed that the Icelandic population of entiation may have occurred in Iceland since the the Interlake District is of the same gene-pool as settlement and that it is preferable to study many, that of Fljotsdalsherad. Yet, these two populations including polyfactorial, traits when estimating have been separated geographically for 3 to 4 gene ethnogenetical relations. His anthropometrical rations. As mentioned above, their genetic re and pigmentation studies of over 10.500 living lationship will be investigated. If our assumption Icelanders and several thousand Norwegians, holds, genetically attributable patterns of health Danes, Irishmen and Scotsmen reveal, that on and disease should be similar in these populations. the whole, Icelanders bear a closer resemblance Differences should therefore, be due to the en to Scandinavian peoples than to the Irish or British vironment. (15, 16, 17, 18, 19). These findings are in accord It appears that the incidence of cardiovascular ance with historical, archaeological and linguistic disease is significantly different in the two popu evidence. lations. The rate of mortality from ischemic heart In the period between 1870 and 1914, disease (IHD) is considerably lower in Iceland than approximately 18.000 Icelanders, about one fifth in North America. Comparative rates for males and of the total population, emigrated to Canada and females in Iceland, the U.S.A., Canada (31}, Mani the U.S.A. Many of these people, chiefly those toba and the so-called »Icelandic ocmmunities» of from Northern and Eastern Iceland, settled in the Manitoba, i.e. the areas inhabited by Icelanders area north of Winnipeg, often referred to as the (13), are shown in Table I. »Interlake District» including »New Iceland». There has been little additional migration of TABLE I. Crude IHD mortality rates for males and Icelanders to the area. Most of the Icelandic in females in Iceland, U.S.A and Canada. habitants are, therefore, descendants of the original settlers. There has been intermarriage be Community Mortalit5 Population Year tween the Icelandic and non-Icelandic residents per 10 size (in 1031 of the district, but our investigation will incorpo rate Canadians who are of Icelandic descent only. Iceland 173 218 1975 As already mentioned, the Icelandic settlers USA 316 211901 1974 of the Interlake District came chiefly from North Canada 231 22413 1974 ern and Eastern Iceland. Our sample in Iceland Manitoba 255 1056 1975 consists of inhabitants of Fljotsdalherad, which Icelandic belongs to this region. Thus, we hope to achieve communities 343 10 1975 a greater genetic comparability of our samples. in Manitoba By selecting those who live in the same district as their parents and grandparents did, we aim at increasing the environmental homogeneity According to these figures, the IHD mortality within the samples. A special advantage in study rates in 1975 were a hundred per cent higher in ing people in Fljotsdalsh&rad is that very complete the Icelandic communities of Manitoba than in 203 Iceland. These are crude figures, but age-standardi creatinine and uric acid. zation reveals that IHD mortality rates in 1975 Spirometric measurements were performed on were 295 and 145 per 105 for males and females subjects in the standing position, using a Vita respectively in the U.S.A., while corresponding lograph Single Breath Instrument and a Peak Flow figures in Iceland were 187 and 83, a difference Meter. Forced vital capacity (FVC), forced expira of some 40 % (30). An age standardized study of tory volume (FEV, FEV1) and maximum air IHD mortality and morbidity amongst Icelanders flow were measured. in Manitoba is planned. Recordings were made of blood pressure (BP) (phases 1, 4 and 5) from the right arm, using an THE FIELD STUDY IN FUOTSDALSHERAD- - Erka mercury-phygmomanometer. Resting BP was Subjects measured on subjects in the supine position after Our sample for the cardiovascular study was 10 minutes rest, during which a conventional 12- drawn from about one thousand people, aged 7 to lead electrocardiogram (ECG) was taken. 60, whose parents and grandparents had lived in Height and weight, femur-condyle and radio Flj6tsdalsherad. They received a letter describing ulnar bone widths, and triceps, subscapular, 8th the procedure and aims of the study a few weeks rib mid-acillar and supra~liac skinfolds were before measurements began. measured. In addition to these various head, face We intended to study six hundred individuals: and body measurements were made and data two hundred aged 7 to 16, divided into on-year collected on various genetic markers, including pig subgroups, two hundred and forty aged 17 to 40, mentation, blood groups, dermatoglyphics and in two-year subgroups and one hundred and sixty others. Photographs were taken of every indi aged 41 to 60, in five-year subgroups. Each sub vidual, and a personality test was administered group was constructed so as to contain equal (16 PF or E.P.O.). As well as studying inhabitants proportions of men and women, and equal pro of Fljotsdalsherad, Palsson has investigated people portions of farmers and village-dwellers. from other districts of Eastern Iceland (Vopnaf· The subjects were chosen randomly, con· jordur and Faskrudsfjordur 1980, Neskaupsstadur tacted by telephone and invited to choose a time 1981 ), and these data are also intended for com convenient for an appointment. 224 individuals, parison with the Icelanders in Canada. aged 7 to 20, were investigated in September and Ergometry was performed with a mecha October 1979, and 307 others, aged 21 to 60, nically-braked bicycle, specially designed by the in June and July 1980. Institute of Work Physiology in Oslo. Expired Of the intended sample, 95 % of 7 to 16 years air was collected in Douglas bags, its volume olds and 85 % of 17 to 60 year olds participated. measured, and air samples analyzed by the Scho Of all 21 to 60 year old potential subjects in lander method, ECG were obtained and BP, res Fljotsdalsherad who did not participate, 25 % - piration and pedalling rates measured during constituting a representative sample of nonparti exercise at three graded work loads. After being cipants with respect to age, sex and residence - tested at two fixed submaximal loads, most of the were subsequently contacted by telephone. Per· children and about 40 % of the subjects aged 21 to sonal and family cardiovascular histories were ob 40 were monitored during peak-effort perform tained along with information on height and ance. The remaining subjects were tested at three weight and the use of medications and tobacco. submaximal work loads. Prior to each 2-minute Members of the intended sample were asked the test period at submaximal loads, subjects cycled reason for nonparticipation, and the majority for 3 minutes to attain »Steady state». The pe responded that work had prevented them from dalling rate was maintained at approximately taking part.