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COMPARATIVE STUDIES OF ICELANDIC PEOPLE LIVING IN AND

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 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

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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 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 , i.e. the areas inhabited by Icelanders area north of , 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. 60 rpm. In the maximum work load test subjects cycled for two minutes to warm up, and were then Procedures and measurements urged to cycle as fast as they could for at least half Blood samples were obtained from subjects after a minute. they had fasted for 8-10 hours, and analyzed The Icelandic Heart Association Ouestionnaire for cholesterol, triacylglycerol, high density lipo­ (14) was used to acquire information about the protein-cholesterol, haemoglobin, haematocrit, medical and social history of participants. It in- 204

eluded questions on family history, health with J.O.: Blodth,.Ystingur He'radsbua aaldrinum 21 til special reference to cardiovascular symptoms, the 60 ara, ibid. use of tobacco and medications, profession, 4. Axelsson, J., Jonsson, 8., SkarphecJinsson, exercjse and housing. Participants also responded J.0. and Way, A. B.: Blood pressure in adult to detailed questionnaires on genealogy and on females in Eastern Iceland. In this volume. exercise during work and leisure. These questions 5. Axelsson, J., J6nsson, S., Oskarsson, J.G. and were sent out to participants a few weeks before PiitursdMtir, G.: Lungnastaerdir og loftskiptageta their scheduled appointments. At the appoint­ Heradsbua a aldrinum 7 til 60 ara, in Radstefna ments interviews reviewed the filled-in question­ um ranns0knir i laeknadeild H3sk61a fslands, 1981. naires in the company of the participants, to 6. Axelsson, J. and Pi!tursdottir, G.: Ukams­ ensure that the questions had been correctly bygging Heradsbua aaldrinum 7 til 60 ara, ibid. understood and answered. 7. Axelsson, J., Sigf6sson, N., Way, A.B. and A nutrition survey was also carried out. 37 Petursd6ttir. G.: Bl6dfita HeradsbGa a aldrinum 21 subjects from our sample aged 12 to 15, all of til 60 ara, ibid. whom resided in Egilsstadir and attended the 8. Axelsson, J., Sigfusson, N .• Way, A.B.,and local school, were interviewed by a trained die· retursdcSttir, G.: Serum lipids in 21 - 60 year old tician and 24-hour intakes recalled. Approxi­ people from Eastern Iceland. In this volume. mately equal numbers of subjects -were inter­ 9. Bjarnason, 0., Bjamason, V.• Edwards, J.H., viewed on each of the different days of the week. Fridriksson, S., Magnusson, M., Mourand, A.E. and The children were interviewed twice: frist in Tiiis, D.: The blood groups of Icelanders. Ann. September 1979 and again, by the same inter­ Hum. Genet. 425458, 1973. viewer, in January 1980. In addition, 33 house­ 10. Brekkan. A.: Bl&dtlokkar 3962 fslenska holds (principally the homes of interviewees) kvenna. Laeknabladid 38: 134-144, 1954. were visited in January and in July 1980, and 11. Einarsson, M.A.: Vedurfar a lslandi, Reykjavf k 48 hour records obtained from the housewives, 1966. who 'Weighed and measured all the food con­ 12. Landnamab6k, £slend Fomrit (Ed.: J. Bene­ sumed at home by each member of the house­ diktsson), Reykjavik, 1968. hold. Mean intakes of energy nutrients, choles­ 13. Manitoba, Dept. of Health and Social Deve­ terol, sucrose, P/S ratios, iron, calcium and vita­ lopment, Vital Statistics registrations. mins have been calculated from these data. 14. Olafsson, 6., Sigvaldason, H., Sigftisson, N., Reports of the study have been given at Bjomsson, 0. and Thorsteinsson, Th.: Epidemio­ meetings in Iceland, Canada, Germany and Den­ logical study of cardiovascular and some other mark, and preliminary results on anthropology, chronic diseases in Iceland. Reykjavik, 1969. body build, serum lipid levels, blood pressure 15. Palsson, J.O.P.: Anthropologische Unter­ and spirometric measurementshave been pub­ suchungen in Island unter besondered Ber'uck­ lished (2. 3, 4, 5, 6, 7, 8, 20, 21, 22, 23, 24, 25). sichtigung des Vergleichs mit den Herkunfts­ In the future field study of Icelanders in liindem der isliindischen Siedler. lnaug. Diss. Canada, all measurements and tests will be carried Mainz, 1967. out by the same personnel, using the same techni­ 16. Palsson, J.O.P.: A report on an anthropo­ ques and equipment; the same laboratory will per­ metric survey of the Icelanders. Vllme Congres form the chemical analyses. International des Sciences Antropologiques et Ethnologiques (Moscow1964), 3: 298-301, 1968. REFERENCES 17. P81sson, J.O.P.: Die Herkunft der isliindishen Bevalkerung in anthropologischer Sicht, S., Be­ 1. Ari frooi Thorgilsson: fslendingab6k, ls­ vf>lkenrungsbiologie, Beitriige zur Struktur und lensk Fomrit I (Ed.: J. Benediktsson). Reykjavfk, Dynamikamenschlicher Populationen in anthro­ 1968. pologischer Sicht (Eds.: Bernhard, W. and Kandler, 2. Axelsson, J.: Samanburdur a Vestur-fslend­ A.): 213-240, Stuttgart 1974. ingum og Heradsbwm, in Radstefna um rann­ 18. Jilsson, J.O.P.: Rassengeschichte derMensch­ soknir i laeknadeild HSskola fslands, Hiil. eit, 4, Europa II, Ost- und Nordeuropa (Ed.: 3. Axelsson, J., JcSnsson, B. and Skarph.!dinsson, Schwidetzky, I.), Miichen-Wien 1976,p. 147-155. 205

19. Palsson, J.0.P.: Some anthropological char­ acteristics of Icelanders analyzed with the problem oc REL HUM. of ethnogenesis. J. Hum. Evol. 7: 695-702, 1978. 90 °/o 20. P3tsson, J.O.P.: Mannfraedistofnun Hiiskola fslands, in Arb6k Haskola fslands 1973-76, Reyk­ javik 1978. 70 21. P

25. Petursdottir, G., Way, A.B., Sigfdsson, N. and J F M A M J J A 8 0 N O Axelsson, J.: Serum lipids in children and ado· 150 lescents from Eastern Iceland. In this volume. PRECIP. mm 26. Sigurdsson, G., Magnusson, G., Sigvaldason, H., Tulinius, H-. Einarsson, I. and 61atsson, 0.: Egisstadaprojektet: problem orienterad journal och individbaserat informationssystem for primiirviird.

Nord. Med. Stat. Kom. Stockholm 1980. cal 27. Steffensen, J.: The physical anthropology of crn2 ·day 400 the Vi kings. J. Royal Anthropol. Inst. Great Brit. and Ir. 83: 86-97, 1953. 300 28. Thompson, E.A.: The Icelandic admixture problem. Ann. Hum. Gen. 87: 69·80, 1973. 200 29. Torgersen, J.: Rassengeschichte von Skandi· 100 navien. In Rassengeschichte der Menschheit, 4, Europa II: Ost- und Nordeuropa. (Ed.: Schwi­ detzky, I.), Miinchen-Wien 1976, p. 103·145. J F M A M J J A S 0 N D 30. Tulinius, H. and Sigvaldason, H.: Aldurs· Fig. 2. Mean temperature and precipitation (1931· stOdlun (Age Standardization), Laeknabladid, 64: 60), relative humidity and solar radiation (1958· 133-136, 1978. 67) per month in Egilsstadir and Hallormsstadur, 31. World Health Organization World Health and mean daily temperature range in Hallorms­ Statistics Annual 1977. I. Vital statistics and stadur (1961-701. causes of death. Geneva 1977.

J6hann Axelsson Professor of Physiology Hjardarhagi 48 Reykjavik Iceland