sociocultural and behavioral influences on health ... · sociocultural and behavioral influences on...

Medical Anthropology, Vol. 17, pp. 165-180Reprints available directly from the publisherPhotocopying permitted by license only

© 1996 OPA (Overseas Publishers Association)Amsterdam B.V. Published in The Netherlands

under license by Gordon and Breach Science Publishers. Printed in Malaysia

Sociocultural and Behavioral Influences onHealth Status Among the Mississippi ChoctawWilliam W Dressler, James R. Bindon and M. Janice Gilliland

Native American populations in North America are at increased risk of a variety of healthproblems, including (but not limited to) diabetes. This risk is presumed to be a result of theinteraction of environmental influences with a population genetic susceptibility.Anthropologists have subsumed those environmental influences under the term"acculturation." Here, we break that broad concept into physical, behavioral, and socioculturalcomponents in an examination of the correlates of arterial blood pressure and plasma glucoseamong the Mississippi Choctaw. In a sample of 93 adults, higher plasma glucose wasassociated with lower physical activity, higher body mass index, and higher lifestyleincongruity, after controlling for age, sex, and recency of food consumption. Higher arterialblood pressure was associated with higher body mass index and being single. These resultssuggest that the risk of disordered glucose metabolism within this Native Americanpopulation is associated with acculturation broadly construed, but that refined models ofhealth and disease must take into account the multiple dimensions of this concept. Physical,behavioral, and sociocultural factors combine to describe more precisely the concept ofacculturation, and hence the factors contributing to the risk of disease in Native Americancommunities.

Key words: Health status, Choctaw Indians, Sociocultural factors

Native Americans are at increased risk of a variety of acute and chroni~ healthproblems. With respect to chronic health problems, high rates of non-insulindependent diabetes mellitus have been observed among some Native AmericanIndian populations, ranging from an approximate 8% prevalence ~mong theDogrib of the Canadian Northvvest Territories, to nearly 25% among the Pima ofArizona; corresponding prevalence rates for non-Hispanic whites range from2-4% (Weiss, Ulbrect, Cavanaugh, and Buchanan 1989). High rates of diabetes,representing an outcome of disordered glucose metabolism, pose questionsabout the adaptation of human populations that have stimulated considerableattention from biological anthropologists. 9ur aim is much more limited. This

WILLIAM W. DRESSLER is Professor of Anthropology and Professor of Social Work at The University of Albama(PO Box 870210/ The University of Alabama, Tuscaloosa, AL 35487). His research interests include thecultural dimensions of stress and disease. He has carried out research among ethnic groups in the US/ and inBrazil. -JAMES R. BINDON is Professor of Anthropology at The University of Alabama (PO Box 870210/ The Universityof Alabama, Tuscaloosa, AL 35487). He has carried out extensive research in Samoa on social change and bodycomposition.M. JANICE GILLILAND is a research associate in the Department of Medicine, the University of Alabama-Birmingham (401 Medical Towers-171711th Ave. S. Birmingham, AL 35294)/ and a doctoral candidate in theDepartment of Health Behavior, School of Public Health, UAB.

165

166 W. W. Dressler et al.

paper will focus on one dimension of the problem-psychosocial factors-that is 'considered of potential importance in the risk of diabetes within NativeAmerican populations, but which has remain~d under-theorized and largelyinadequately analyzed.

DIABETES, HUMAN ECOLOGY, A~D ADAPTATION

Ritenbaugh and Goodby (1989) have reviewed the literature on populationadaptation and glucose metabolism. The risk of diabetes among NativeAmericans has been traced to the adaptive demands posed by the migration ofthe ancestral populations into the New Wp~ld. Hunters and harvesters crossingthe land bridge between the Old and New Worlc~sinto what is now Alaska arehypothesized to have faced the problem of an irregular food· supply. The mostregular feature of that food supply would have been marine animals and herdungulates, resulting in a diet low in carbohydrates and fiber, moderate in fat, andhigh in protein. The energy demands placed on this fuel supply included activityfor hunting and the maintenance of body temperature.

Irregularity of the food supply led Neel (1962)to posit a "thrifty genotype" asthe population basis for diabetes risk. That is, the regular liability to severe foodshortages selected for a genetic adaptation to store energy. This adaptation, inthe presence of regular food supplies, became problematic and led to increasedobesity and risk of diabetes. As Ritenbaugh and Goodby (1989: 227) note,however, this is a very general concept that is not anchored .by actual metabolicor genetic mechanisms. They go on to discuss two specific pathways that mightbe linked directly to glucose metabolism. These include the possibility that agenetically determined disorder of lipid metabolism results in diabetes (Weiss,Ferrell, and Hanis, 1984). A second possibility is that a more specific"glucose-sparing" genotype was selected for because of a very low glucose (i.e.low carbohydrate) diet (Szathmary 1986). Irrespective of the specific genetic ormetabolic mechanism, the end result is the same: ancestral Native Americanpopulations adapted to an environment in which specific forces selected for aspecific genotype, and to the extent that those forces are no longer present, thatgenotype results in enhanced risk of chronic disease.

Lending credence to the view that there is a population genetic susceptibilityto diabetes among Native Americans is the relatively low rate of other chronicdiseases, ,especially cardiovascular disease (Dressler 1984).The rate of essentialhypertension (or chronically elevated blood pressure) is substantially loweramong Native American groups tha~ in the general U.S. population (Kunitz andLevy 1991:79). It would seem that any glucose-sparing genotype selected for inmigration to the New World has little effect on blood pressure.

Even assuming a genetic susceptibility to diabetes, it is likely thatenvironmental influences are also important as "triggers" for the onset of thedisease. Anthropologists have employed terms such as "acculturation" and"changing lifestyles" to describe the influences leading to increased risk ofdiabetes (Ritenbaugh and Goodby 1989).The use of these terms among someant~ropologists mimics their use among biomedical scientists: "acculturation"

Health Status among the Choctaw 167

and "lifestyle" have come to be equa"tedwith changes in diet, activity patterns,the distribution of obesity, and the use of tobacco and alcohol, all of which arebelieved to combine to determine the risk of "diseases of civilization" such ascardiovascular disease and diabetes (Trowell and Burkitt, 1981; Coreil, Levin,and Jaco 1985). Thus, it is argued that the "acculturation" of Native Americans toa high fat, high prote'in diet, along with an increase in "sedentary lifestyles,"results in higher rates of obesity and the onset of diabetes.

There are, however, findings that are inexplicable under this model. Forexample, Szathmary and Ferrell (1990) presented an analysis of glucose level andacculturation among the Dogrib of the Northwest territories of Canada. TheDogrib have a very low rate of diabetes. In an analysis of dietary factors in therisk of diabetes, there was a persistent main effect (in analysis of variance terms)of village (versus more isolated) residence. In the face of the adjustment for avariety of factors, including dietary carbohydrate intake, triglyceride levels, andhand grip strength (a measure of physical fitness),.residence in the main villagein the region was associated with a higher risk of "diabetes (as measured byglycosylated hemoglobin).

The authors describe the Dogribas residentially divided between one mainvillage and smaller dispersed, isolated settlements. Village residents, who makeup seventy percent of this specific Dogrib band, live in a much more denselypopulated community, are more sedentary than others, interact with a greaterproportion of non-Indians, have access to commercial restaurants and retailoutlets, and are more likely to engage in wage':'labor employment (Szathmaryand Ferrell 1990: 319). The authors suggest, based on the differences betweenvillage residents and others, thaf "psychosocial stress" is higher among thevillage-dwelling Dogrib, which in turn is related to an increased risk of diabetes.

The notion that psychosocial stress might be related to the risk of diabetes isnot new (Weiss and English 1949: 521; Scheder 1988). Frequently, however, theconcept of stress is dealt with rather uncritically in the anthropologicalliterature. 1 Often stress is used synonymously with a variety of mental states,including anxiety, tension, worry, and fear, assuming some sort of isomorphismbetween broad descriptors of the social environment (such as acculturation) andthese (equally general) mental states, which in turn are associated withpsychophysiologic reactivity and risk of disease (Dressler 1996). An alternative tothis general usage is to attempt to break down abstract concepts such asacculturation or socioeconomic status into more specific and precise social andpsychological factors, and to examine how such factors combine to increase therisk of disease (Bindon and Dressler 1992).

One such model has been proposed as a "sociocultural model of disease risk"(Dressler 1993). This model decomposes the general processes' described byacculturation into specific social and behavioral factors affecting individuals. Oneof the most potent of these factors is status incongruence (described below), whichhas been found to be associated with depressive symptoms (Dressler 1991), bloodpressure (Dressler 1982, 1993; Bindon, Crews, and Dressler 1991), and serumcholesterol (Dressler,et al. 1991). In the remainder of this paper status incongruencewill be examined, relative to competing explanatory factors, as a correlate ofplasma glucose and arterial blood pressure among the MississippiChoctaw.

168 W. W.'IDressler et al.

STATUS INCONGRUENCE AND DISEASERISK

Socioeconomic differentiation is a fundamental concomitant of acculturation.This concept refers to an increase in the socioeconomic distance betweenhouseholds. In communities experiencing rapid and profound social change,especially involving increasing penetration of the community by a capitalistmarket economy, some members of the community are able to take advantage ofnew opportunities for wage-labor, education, and the accumulation of newconsumer goods, while others are not able to adopt such changes. It is almostinvariable under these conditions of social change that higher prestige or socialstatus comes to be associated with greater "success" in adopting new and visiblestyles of life. One important dimension of these higher prestige lifestyles is theaccumulation of consumer goods and the adoption of related behaviors. Thehigher status associated with such consumer lifestyles are reinforced in the massmedia (Dressler 1985).

A major problem in this process occurs when individuals attempt to attainand maintain a higher status lifestyle in lieu of real change in their economicstatus ..For example, an individual may attempt to accumulate valued consumergoods without an associated increase in hi's or her level of education oroccupational status. He or she may then be communicating in social interaction aclaim to the prestige associated with lifestyle·consumption, but it is a claim thatis not buttressed by other indicators of economic success. The result is adiscrepancy among different ways of ranking the individual within thecommunity system of prestige. Such discrepancies can lead to confusion anduncertainty in social interaction, since individuals possess conflictinginformation as to one another's social status (Goffman 1951). It is thisdiscrepancy that, in general, has been referred to as status incongr~ence, and,more specifically, as "lifestyle incongruity;" it has been found to be associatedwith a variety of chronic health problems (Dressler 1993,1996).

In interpreting this effect, primary emphasis has been placed on thephysiologic effects of social interaction, because research has found repeatedlythat association between lifestyle incongruity and health outcomes isindependent of conventional measures of psychosocial stress, such as stressfullife events or measures of chronic perceived stress (Dressler 1996). It wouldappear, then, that there are two pathways by which these factors influencehealth. One, involving psychosocial stress, is through the perceptions of threatassociated with chronic or acute stressors. The second, involving statusincongruence, is through the effect of social interaction on physiologic andmetabolic adjustment (Dressler 1993).

Social and psychological factors are not the only ones of relevance to healthoutcomes in situations of acculturation or social ch,ange. Evidence exists thatindeed diet, physical activity, and the prevalence of obesity also change inconcert with social and behavioral changes (Bindon and Zansky, 1986; Greksa, eta1.1986). It is therefore incumbent upon investigators to incorporate theoreticallyuseful and operationally valid measures of as many of these factors as possible.The focus here will be on the association of lifestyle incongruity, psychologicalstressors;, physical activity, and body composition with plasma glucose and


arterial blood pressure among the Mississippi Choctaw, a Native Americangroup which has experienced profound social changes during the past twodecades.

ETHNOGRAPHIC SETTING: THE MISSISSIPPICHOCTAW

The Mississippi Choctaw have a population of approximately 6,000 persons(according to tribal rolls supplied to the authors) distributed across sevencommunities in eastern Mississippi. The tribal headquarters and the greatestconcentration of the population are located in Neshoba County, Mississippi nearthe small town of Philadelphia.

To a large extent, the Choctaw are a cultural, linguistic, and economic isolatein the region. Prior to the removal of Native Americans in the early 19thcentury,the Choctaw controlled a large portion of present-day Mississippi and Alabama,and pursued a mixed horticulture and hunting subsistence economy. AsEuroamericans extended their hegemony throughout the southeast, the Choctawwere forced increasingly to occupy marginal land. In 1830,the Treaty of DancingRabbit Creek was concluded which stipulated the removal of the Choctaw to anarea west of the Mississippi River (in present-day Oklahoma) and the ceding oftheir land east of the river to the federal government. One provision, however,allowed for some Choctaw to remain east of the river and to receive allotments ofland. Some 5,000 elected to, do so and formed the basis for the contemporaryMississippi Choctaw community (McKeeand Schlenker 1980:64).

Throughout their history, the Choctaw have remained distinct from the twodominant ethnic groups in the region; Euroamericans and African Americans.Until the end of the Civil War, individual Choctaw families attempted to exercisetheir rights to land allotments, only to be frustrateq by a government thatfavored removal (McKee and Schlenker, 1980). In lieu of receiving landallotments, families often struggled to maintain themselves on marginalagricultural land. Ironically, post-emancipation economic changes helpedstabilize the Choctaw's situation by enabling them to ,participate in the system ofsharecropping (Peterson 1972).By sharecropping, Choctaw could remain in theirown communities, working the land independently, and retain their ethnicdistinctiveness. This relative economic stability, along with the establishment ofChoctaw schools and churches, contributed to their cultural survival (Peterson1972).

In 1903 the federal government attempted the so-called second removal, butagain a substantial population ofChoctaw (from 1,000to 1,500persons) chose 'toremain in Mississippi. In 1918, after visits to Mississippi by Bureau of Indian'Affairs officials documenting severe living conditions and an influenza epidemicthat caused several hundred deaths, the U.S. Senate established the ChoctawAgency in Philadelphia, Mississippi (McKeeand Schlenker 1980).A federal landpurchase followed that allowed for the greater concentration of the Choctawaround Philadelphia (Peterson 1972).

For fifty years after the establishment of the Choctaw Agency, socialconditions were little changed for the Choctaw. A new hospital improved health


care somewhat for the population, and elementary schools were built to servemost Choctaw communities. But as Peterson has not.ed,by 1968:Slightly over half of the population lived on trust land, and the median years of school completed byChoctaw heads of households was three. Over a third of the heads of households were unemployedand approximately a third worked only as temporary farm laborers ... Choctaws faced thea.lternatives of unemployment, welfare, or migration to other areas (Peterson 1992: 142).

But the 1960s, and the social policy experiments initiated by the civil rightsmovements and the Johnson administration's Great Society programs, saw thebeginning of what the Choctaw tribal government later called" An Era ofChange" (Peterson 1992).

Political innovations initiated by the Choctaw themselves resulted in true localcontrol in decision-making. According to Peterson's (1992) analysis of thesituation, ':'theChoctaw used their political control to pursue a distinct path ofeconomic development. This development strategy included obtaining federalgrants and contracts to establish programs such as Head Start and other socialservices, to initiate an extensive Choctaw housing program carried out by theirown construction company and, ultimately, to develop an industrial park andestablish six different factories offering employment opportunities for theChoctaw.

Today a Choctaw community looks much like any other small town orsubdivision. Yet half of the sample for the current study exclusively speakChoctaw at home. In 1970 the median family income for the Choctaw wasaround $3,000 (McKee and Schlenker 1980),while in the current sample it wasapproximately $15,000.In the current sample, respondents report a mean of 9.4years of education, compared to the median of 3 years in the late 1960s.In short,the Choctaw' strategy of development 'has resulted in rapid change for thepopulation, but to a certain extent change has enabled the Choctaw to retain theirethnic identity, as indicated by language use (Thompson and Peterson 1975).

This context of social change precisely parallels a process that has resulted inincreased rates of chronic disease in other societies (Dressler 1985).While able tomaintain their ethnic identity through the maintenance of their language, theChoctaw have not been immune from the values placed on a consumer lifestyle inthe larger American society. As ~dividuals are variably able to take advantage ofnew' opportunities for upward economic mobility, it is likely that some attempt tomaintain such a lifestyle inconsistent with their actual economic status as assessedby occupation, education, income, and employment status. This lifestyleinc;ongruityis a chronic stressor that may be related to an increased risk of chronicdisease. Such risk would be indicated by higher arte'rial blood pressure andplasma glucose levels. By the same token, the economic changes observed amongthe Choctaw can also be related to increasing rates of.obesity and decreasinglevels of physical activity. The relative effects of these factors will be assessed.

SAMPLING AND METHODS

Tribal rolls were used to sample adults (> 21) living in the vicinity ofPhiladelphia, Mississippi. The universe to be sampled was estimated to be 2,000


persons. A simple random sample of 139individuals was selected, and completedata were obtained for 93(67%) of this original sample, about an averagecompletion nite for a field study. Those who refused to participate were only asmall minority of the uncompleted interviews; most resulted from either aninability to'contact sampled individuals, or difficulties in'scheduling.

Interviews were conducted at a location convenient to the respondent, mO$toften his or her home (68.8%).Other interviews were conducted either at theChoctaw Health Center, or in various workplaces around the reservation, mostlyat the tribal headquarters. All interviews were conducted in private. A nativeChoctaw speaker served as translator when necessary. All interviews andmeasurements were completed by one researcher (M.J.G.).

Arterial blood pressure was measured using the auscultatory method with ananeuroid sphygmomanometer that had been calibrated against a mercuryinstrument. A large-arm cuff was available. Three blood pressure rea~ings weretaken on the left arm of persons who were seated with their arm supported atheart level. First and fifth phase sounds were recorded. The three readings werethen averaged.

Random capillary biood glucose was measured with a GLUCOSCANBloodGlucose Meter and GLUCOSCAN Test Strips manufactur~d by Lifescan Inc.(Mountain View, CA 94043). This is a dry reagent test using glucose oxidasewhich is specific for D-glucose.A drop of capillary blood is applied to a test stripand the concentration of glucose is determined by a flurometric method anddisplayed as milligrams per deciliter of sample applied. The meter wasmonitored on a daily basis with the standard test strip supplied by themanufacturer, and no significant change in the test values was noted over thestudy period. Random glucose is the least desirable measurement of bloodglucose in attempting to assess diabetic status or control; however, the logisticsof the overall health risk survey precluded measurement of early morningfasting glucose or the administration of a glucose tolerance test.2 For plasmaglucose, minutes since last meal is included as a covariate; since this influencescasual glucose readings.

Self-reported treatment status is a dichotomy indicating both whether or notthe respondent has ~een told he or she is hypertensive or diabetic, and whetheror not he or she is currently engaging in any palliative behaviors (e.g. takirigmedication and/ or following a special diet). '

The Quetelet Index of body mass (kg/m2). is used to measure obesity. Four

straightforward questions about physical activity at work and during leisuretime were. asked. Responses to the questions were summed, unweighted, toarrive at a total physical activity score.3

Dressler's (1985) 25-item style of life scale was used (Table I). This scaleassesses the .accumulation of consumer goods and the adoption of behaviors thatincrease the individual's exposure to messages in the mass media regardinglifestyles. The scale shows acceptable internal con\sistency reliability (alpha =0.85) ..

Occupations of all employed persons in the respondent's household wereranked on a six-point scale and household occupational scores were derived bysumming these ranks. Occupational scores, total household income, respondent's


Item

TABLE IScale of style of life"

Descriptivestatistic

Item-remaindercorrelaltion

1. Telephone2. Color TV.3. Tape deck4. Stereo5. Microwave6. VCR7. Cable TV8. Air conditioning9. Cars10. Travel-in state11. Travel-US12. Travel-international'13.Reads new magazines14. Reads house magazines15. Reads sports magazines16. Reads tribal newsletter17. Reads religious magazines18. Vacations'19. Reads newspapers20. Listens to radio news21. Watches TV news22. Goes to movies23. Reads books24. Watches TV25. Belongs to associations

0.39 0.26 '1.01 0.470.49 0.360.63 0.300.33 0.320.67 0.320.38 0.370.34 0.301.46 0.401.06 0.290.59 0.450.01 0.241.79 0.601.41 0.501.59 0.502.09 0.621.73 0.550.70 0.391.15 0.722.02 0.280.23 0.320.23 0.321.03 0.521.90 0.340.63 0.32

Internal consistency reliability (alpha) = 0.85

"Note: Items 1,3-8 are dichotomiesItems 2, 9, 25 are counts.Items 10-12 and items 18-24 are rated on a 4-pt scale of frequency.Items 13-17 are rated on a 3-pt. scale of frequency.

years of education, and respondent's employment status were found to load asingle principal component of economic status (Table II). Principal componentscores were calculated with standard regression methods.

The style of life scale and the economic status score were used to calculate twonew variables. The first, "lifestyle incongruity," assesses the degree to which

TABLE IIPrincipal comp<?nent loadings for economic status.

Item Loading Mean (± s.d.)

1. Occupational class 0.875 2.45 (2.42)2. Education 0.700 9.44 (4.61)3. Income 0.749 2.54 (1.08)4. E~ployment status 0.794 0.64 (0.48)

Eigenvalue 2.45% Total variance 61.20


style of life exceeds economic status. Each component variable is first convertedto a distribution with a mean of 50 and a standard deviation of 10.4 Lifestyleincongruity thus becomes: (style of life-economic status). The second calculatedvariable, "socioeconomic status," thenbecomes: (style of life + economic status).Socioeconomic status thus measures overall standing in the status hierarchy,while lifestyle incongruity measures the discrepancy in two major components ofoverall standing.s

Psychological stress is measured with a 10-item scale assessing the individualrespondent's feelings of depression, anxiety, worry, tension, life satisfaction,perceived strength of social ties, and experience of recent life events. This scalewas created specifically for this study from available items in the interviewschedule and combines items regarding mood, chronic stress, and acute stress(see Cohen, Kessler, and Gordon 1995 for a general discussion of stressmeasurement). The scale exhibits adequate internal consistency reliability (alpha= 0.70).

Age, sex, and marital status are included in all analyses ascovariates.

RESULTS

Descriptive statistics for the study population are shown in Table III.Ordinary least squares multiple regression analysis is the data analytic tool of

choice here, given that the dependent variables are continuously distributed. Ahierarchical analysis is used in which all variables are forced into the analysis onthe first step, save one: treatment status. On the second step, treatment status isadded. Because an explicit model is being tested with the direction of theanticipated effects stipulated in advance, I-tailed tests of statistical sigriificanceare reported .. , '

The regression analysis of plasma glucose is shown in Table IV . Higher body

TABLE IIIDescriptive statistics for variables used in the analyses.

Variable

1. Plasma glucose2. Systolic blood pressure3. Diastolic blood pressure4. Age5. Sex (% female)6. Marital status (% married)7. Socioeconomic status8. Body mass index9. Physical activity

10.Time since last meal11. Lifestyle incongruity12. Psychological stress13. In treatment for diabetes (%)14. In treatment for hypertension (%)

118.7 (±61.4)128.6 (±17.8)80.6 (±12.2)39.9 (±13.2)53.860.2

100.0 (±18.5)31.2 (±S.8)3.9 (±1.8)

295.2 (±228.4)0.0 (±7.7)

11.1 (±3.5)25.834.4

174 W. W.'Dressler et al .

• TABLE IVHierarchical regression analysis of plasma glucose.

(standardized regression coefficients) .

Variable

1. Age2. Sex3. Time since last meal4. S~cioecof).omic status5. Marital status6. Body mass index7. Physical activity8. Lifestyle incongruity9. Psychological stress

10. Treatment statusR=R2=

*p < 0.05**p< 0.01

Step 1

0.168-0.006-0.093-0.1350.0500.154*

-0.243*0.202*0.044

0.546**0.298

Step 2

-0.177**0.0780.001

-0.0190.0540.074

-0.219*0.230**

-0.0550.692**0.762**0.582

mass index and higher lifestyle incongruity are both associated with higherplasma glucose. Higher physical activity is also associated with lower plasmaglucose. When treatment status is put into the analysis, the effect of the bodymass index drops to nonsignificance, while the effects of physical activity andlifestyle incongruity remain significant.

The regression analysis of arterial blood pressure is shown in Table V. In thefirst step of the analysis, higher systolic blood pressure is associated with ahigher body mass index, older age, male sex, not being married, and lowerpsychological stress. The correlates of diastolic blood pressure are slightly

TABLE VHierarchical regression analysis of systolic blood

pressure (SBP) and diastolic blood pressure (DBP).(standardized regression coefficients)

Variable Step 1 Step 2

SBP DBP SBP DBP

1. Age 0.284** 0.048 0.149 -0.812. Sex -0.225** ~0.155 -0.232** -0.1613. Socioeconomic status 0.011 0.103 0.080 0.1714. Marital status -0.202* -0.295** -0.230** -0.322**5. Body mass index 0.246** 0.211* 0.184* 0.1516. Physical activity -0.082 -0.066 -0.078 -0.0627. Lifestyle incongruity -0.040 -0.51 0.002 -0.0098. Psychological stress -0.170* -0.96 -0.135 -0.0629. Treatment status 0.373** 0.363*

R= 0.531** 0.387** 0.619** 0.496**R2= 0.282 0.150 0.384 0.246

*p < 0.05**p< 0.01

I _


different in that age and psychological stress are not significant. When treatmentstatus enters the analysis for systolic blood pressure, age and psychological stressdrop to nonsignificance. After entering treatment status in the analysis ofdiastolic blood pressure, only the effect of marital status remains significant.

DISCUSSION

These results are consistent with an orientation in which acculturation, broadlydefined, is associated with an elevation of plasma glucose ( which in turn'can beinterpreted as an indicator of an increased risk of diabetes). But '~acculturation"is too blunt a theoretical tool to alone unravel the process involved. Rather, theconcept of acculturation must be broken down into its component parts, each ofwhich is independently associated with diabetes risk. In this, study, theseindependent components include physical (body mass), behavioral (physicalactivity), and sociocultural (lifestyle incongruity) factors.

One striking outcome of this study was the failure of lifestyle incongruity (orphysical activity) to be associated with blood pressure, a failure which, in light ofprevious studies (e.g. Dressler 1982, 1991;Dressler, Santos, et al. 1987;Dressler,Mata et al. 1987),is interesting. One interpretation for this finding is that there isa population genetic substrate upon which all' environmental factors operate.Because of the selection for the "thrifty genotype" throughout the period ofmigration to the New World-whatever precisely that genotype is-NativeAmericans are vulnerable or susceptible to environmental variation through thatspecific physiologic/metabolic pathway. In turn, the observed effects of generalrisk factors such as obesity, physical activity, and lifestyle incongruity will bemanifest primarily through that pathway. In this way, these factors may beassociated with variability in disordered glucose metabolism among NativeAmericans, and then may be associated with, for example, disordered bloodpressure regulation in another population, or perhaps disordered lipidmetabolism in another. This theoretical orientation is consistent with Cassets(1976)concept of "generalized susceptibility."

The results of this study challenge the notion that population geneticsusceptibility is the sole basis for diabetes risk here. Rather, these resultsdemonstrate that physical, behavioral, and sociocultural factors intersect todetermine that risk. As a way of examming the risk strength of the association ofthese factors with casual plasma glucose, it is useful to calculate the contributionof each one of the variables to differences in glucose between individuals (basedon the regression coefficients from Table IV).An,individual who is at the samplemean on every variable in that analysis would have a casual plasma glucose of123.5mg/ dl. If this hypothetical individual was one standard deviation belowthe mean on physical activity, this glucose would increase by 14.9 mg/ dl to138.4.If this person was also one standard deviation above the mean on lifestyleincongruity, plasma glucose would increase to 150.9 (or another 12.5 mg/dl).Finally, if that person also was one standard deviation above the mean on thebody mass index, plasma glucose would increase to 160.5(or another 9.6mg/dl).Weiss and colleagues (1989)suggest that a casual plasma glucose, as measured

'176 W. W. Dressler et al.

by glucoineter, in excess of 120mg/ dl is grounds for more precise testing viastandard clinical testing to rule out diabetes. It would appear, therefore, that thefactors identified here are of biological significance.

Interpreting these results in this way requires that confidence be placed in thereliability of the measurement of casual glucose, which, as we have alreadypointed out, is the weakest (i.e. least reliable) measure of disordered glucosemetabolism. Fortunately, there are additional data to suggest that the casualglucose measurements used here are reliable. Health center records werereviewed for the respondents. For 6i of the 93 members of the sample, a casualglucose measurement was recorded in the chart. For these respondents, thecorrelation between health center and our glucose readings is r = 0.77 (p < 0.001),indicating stability in the measurement. Also, clinical diabetes had beendiagnosed on 28 of the 93 (or 30.1%) respondents. A oneway analysis of varianceof casual glucose readings for diagnosed diabetics versus other respondents washighly significant (F = 80.63; df = I, 92; P < 0.001). The mean casual glucosereading for diagnosed diabetics was 182.5 (95% confidence intervals=155.6,209.5), and the mean casual glucose reading for nondiabetics was 91.3 (95%confidence intervals=84.0, 98.5). Thus/the casual glucose readings appearreliable.

The mechanisms'by which body mass and phYSicalactivity influence glucosemetabolism have been discussed already (Ritenbaugh and Goodby 1989). Themechanism through which lifestyle incongruity might operate requires furtherexplication. A consistent finding in this regard is the independence of the effectof lifestyle incongruity on various outcomes from typical measures ofpsychological stress.7 The independence of lifestyle incongruity frompsychological stress has been observed in a variety of studies, using a variety ofoutcome variables, -and, especially, using different measures of psychologicalstress (Dressler 1991, 1993). The measures of psychological stress used rangefrom simple ones such as that used in this study, to very specific measures ofchronic social role stressors and stressful life events. Consistently, the effect oflifestyle incongruity is independent of psychological stress.

It seems likely that a process involving more than perceptions of stress isinvolved. Rather, the primary mechanism may be through social interaction andphysiologic arousal associated with interaction (Dressler 1990).Adoption of ahigher status style of life is a means by which individuals attempt tocommunicate an image of themselves-a social identity-to others. But asGoffman (1951)pointed out, if that higher status social identity is perceived byothers to be inappropriately manipulated, it is unlikely to be confirmed inmundane interaction. The adoption of a high-status lifestyle in lieu of the socialor educational "capital" (to borrow Bourdieu's (1984)phrase) to back it up, thatis, in association with commensurate occupational, employment, and educationalcredentials, may be perceived by others as inappropriate, and lead to therejection of that assumed social identity. This will leave the individual in a stateof more-or-Iess continual struggle and vigilance in social interaction, attemptingto attain a social identity forever denied him or her. The physiologic effects ofsuch a continued vigilance have been described by others (Henry 1982), andthese effectswould influence glucose metabolism.

1--


There are inherent weaknesses in this study. The problems with themeasurement of casual glucose have been discussed in detail. Another probleminvolves the small sample size. The danger here is that, in some u'nknown way,the sample selection procedures have interacted with the measurementprocedures to generate observed results; however, the small sample size and lowpower research design would actually have mitigated against the detection ofeffects rather than increased· the likelihood of generating spurious effects. Also,the inspection of regression diagnostics indicated no influential cases.8

A final point worth noting is that the associations of the various variables withplasma glucose are not confounded with treatment status. In fact, the strength ofthe association of lifestyle incongruity with plasma glucose is enhanced byadjusting for treatment status. The attenuation of the effect of the body massindex is probably not a function of that being a spurious effect; rather, it isprobably a function of clinical decision_making. Clinic personnel are probablymore likely to test obese people for glucose tolerance, hence leading them to beselectively treated relative to normal weight persons. It is this selection factorthat probably explains the dependence between treatment status and body mass.

Future research should consider additional factors in sorting out theserelationships. Only one dimension of a sociocultural model of disease risk(Dressler 1993) has been examined ·here. Culturally appropriate measures ofsocial supports and coping style should be incorporated into a model; theassociation of marital status with lower blood pressure may be indicative of theempirical value of including social supports. Similarly, measures of dietaryintake would be useful, given the likelihood of diabetes risk being associatedwith a particular dietary pattern.

This study will hopefully serve as an impetus for more research in thebiocultural epidemiology of disordered glucose metabolism. From ananthropological perspective the study of glucose metabolism represents anopportunity to examine processes of adaptation, both in terms of how:contemporary populations represent the cumulative outcome of adaptations topast ecological circumstances, and in terms of how individuals adapt to thechanging social and historical circumstances in which they find themselves.

ACKNOWLEDGEMENTS

Research was funded by the Research Committee of the College of Community Health Sciences, TheUniversity of Alabama. Our deepest gratitude goes to the Choctaw Tribal Council and the people ofthe Mississippi Band of the Choctaw for their encouragement in this study.

NOTES

L To their credit, Szathmary and Ferrell (1990) are explicit concerning the lack of directmeasurement, and hence evidence of, psychosocial stress among village residents; rather, theyoffer it as an hypothesis.


2. Plasma glucose readings had a range of 52-320, with a median value of 96; these values, alongwith the mean (see Table III) indicate a somewhat skewed distribution (skewness = 1.64). Therewas, however, no evidence of bimodality in the distribution. Log transformations improv:edsomewhat, but did not normalize, the distribution. The results of the regression analysispresented in the results section were essentially unchanged using untransformed, transformed,or dichotomized (at glucose = 120, with logistic regression) values for plasma glucose. Sincethere were no differences in the results between ordinary least squares regression analysis andlogistic regression, and, since regression diagnostics failed to indicate any influential cases (seenote 8), it is unlikely that any departures from normality in the distribution of plasma glucosehad substantial effects on the observed results of these analyses.

3. Basic psychometrics are inappropriate for this scale since there is no expectation that greater (orlesser) physical activity at work will be related to greater (or lesser) physical activity duringleisure. "

4. The formula for creating these scores is: ([(xj-m)/s.d.] + 5) x 10), where "x;" are individual scores,"m" is the mean of the distribution, and "s.d." is the standard deviation of the distribution.

5. For a more detailed exposition of the logic requiring the inclusion of both the sum of and thedifference between these factors, the interested reader is referred to Whitt's (1983) review.

6. The exact age and sex distribution for the sample is as follows:

MalesFemales

Age: < 2552

25-341915

35-449

13

45-5478

55 and older3

12

Total4350 .

7. And of course, in these data, psychological stress is related to systolic blood pressure in the"wrong" direction. It would be beyond the scope of this paper to address this issue in any detail.Suffice it to say that there are numerous examples of various measure of psychological stresscorrelating with outcomes in the "wrong" direction. All this points to is the need for bettertheory and measurement in the area.

8. Regression diagnostics include conventional measures such as residuals, as well as what arecalled leverage values and measures of changes in the regression coefficients with the deletion ofcases (Bollen and Jackman 1985). The deletion of even mildly suspect cases actually increased thestrength of reported results.

REFERENCES

Bindon, J. Rand S. Zansky1986 Growth and Body Composition. In The Changing Samoans: Behavior and Health in

Transition. P. T. Baker, J. M. Hanna, and T. S. Baker, eds. Pp. 222-253. New York: OxfordUniversity Press.

Bindon, J. R, D. E. Crews, and W. W. Dressler1991 Life-style, Modernization, and Adaptation Among Samoans. Collegium Antropologicum 15:

101-110.Bindon, J. Rand W. W. Dressler

1992 Social Status and Growth: Theoretical and Methodological Consideration. In Health andLifestyle Change. R Huss Ashmore, J. Schnall and M. Hediger, eds. Pp. 611-70. MascaResearch Papers in' Science and Archaeology, Vol. 9. Philadelphia, PA: University ofPennsylvania.

Bollen, K. A. and R. W. Jackman1985 Regression Diagnostics: An Expository Treatment of Outliers and Influential Cases.

Sociological Methods and Research 13: 510-542.Bourdieu, P.

1984 Distinction: A Social Critique of the Judgment of Taste. Cambridge, MA: Harvard UniversityPress.

i

Ii~


Cassel, J.1976 The Contribution of the Social Environment to Host Resistance. American Journal of

Epidemiology 104: 107-123.Coreil, J., J. S. Levin, and E. G. Jaco1985 Lifestyle-an Emergent Concept in the Sociomedical Sciences. Culture, Medicine and

Psychiatry 9: 423-437.Cohen, S., R. C. Ke~sler, and L. Underwood Gordon

1995 Measuring Stress: A Guide for Health and Social Scientists. New York: Oxford UniversityPress.

Dressler, W. W.1982 Hypertension and Culture Change: Acculturation and Disease in the West Indies. South

Salem, NY: Redgrave Publishing Company.1984 Social and Cultural Influences in Cardiova.scular Disease: A Review. Transcultural

Psychiatric Research Review 21: 257-'-286.1985 Psychosomatic Symptoms, Stress, and Modernization: A Model. Culture, Medicine, and

Psychiatry 9: 257-286.1991 Stress and Adaptation in the Context of Culture: Depression in a Southern Black

Community. Albany, NY: State University of New York Press.1993 Social and Cultural Dimensions of Hypertension in Blacks: Underlying Mechanisms. In

Pathophysiology of Hypertension in Blacks. J. G. Douglas and J. C. S. Fray, eds. Pp. 69-89.New York: Oxford University Press ..

1996 Culture, Stress, and Disease. In Medical Anthropology: Contemporary Theory and Method.T. M. Johnson and C. F. Sargent; eds. Pp. 252-271. Westport; CT: Praeger.

Dressler, W. W., A. Mata, A. Chavez, and F. Viteri1987 Arterial Blood Pressure and Individual Modernization in a Mexican Community. Social

Science and Medicine 24: 679':"687;Dressler, W. W., J. E. Dos Santos, P. N. Gallagher, Jr., and F. E. Viteri

1987 Arterial Blood Pressure and Modernization in Brazil. American Anthropologist 89: 389-409.Dressler, W. W., J. E. Dos Santos, F. E. Viteri, and P. N. Gallagher

1991 Social and Dietary Predictors of Serum Lipids: A Brazilian Example. Social Science andMedicine 32: 1229-1235.

Goffman, E.1951 Symbols of Class Status. British Journal of Sociology 2: 294-304.

Greksa, L. P., D. L. Pelletier, and T. B. Cage1986 Work in Contemporary and Traditional Samoa. In The Changing Samoans: Behavior and

Health in Transition. P. T. Baker, J. M. Hanna, and T. S. Baker, eds. Pp. 297-326. New York:Oxford University Press.

Henry, J. P.1982 The Relation of Social to Biological Processes in Disease. Social Science and Medicine 16:

369-380.Kunitz, S. J. and J. E. Levy

1991 Navajo Aging: The Transition from Family to Institutional Support. Tucson, AZ: TheUniversity of Arizona Press.

McKee, J. O. and J. A. Schlenker1980 The Choctaws: Cultural Evolution of a Native American Tribe. Jackson, MS: University Press

of Mississippi.Neel, J. V.

1962 Diabetes Mellitus: A "Thrifty" Genotype Rendered Detrimental By "Progress." AmericanJournal of Human Genetics 14: 353-362.

Peterson, J.H., Jr.1972 Assimilation, Separation, and Out-Migration in an American Indian Group. American

Anthropologist 74: 1286-1295.1992· Choctaw Self-Determination in the 1980s. In Indians of the Southeastern United States in the

Late 20th Century. J. A. Paredes, ed. Pp. 140-161. Tuscaloosa, AL: The University ofAlabama Press.

j


Ritenbaugh, C. and c.-S. Goodby1989 Beyond the Thrifty Gene: Metabolic Implications of Prehistoric Migration into the New

World. Medical Anthropology 11: 227-236.Scheder, J. C.

1988 A Sickly-Sweet Harvest: Farmworker Diabetes and Social Equality. Medical AnthropologyQuarterly 2: 251-277.

Szathmary, E. J. E.1986 Diabetes in Arctic and Subarctic Populations Undergoing Acculturation. Collegium

Antropologicum 10: 145-158.Szathmary, E. J. E. and R. E. Ferrell

1990 Glucose Level, Acculturation, and Glycosylated Hemoglobin: An Example of BioculturalInteraction. Medical Anthropology Quarterly 4: 315-341.

Thompson, B. and J. H. Peterson1975 Mississippi Choctaw identity. In The Ne"Y Ethnicity: Perspectives from Ethnology. J. W.

Benhett, ed. Pp. 179-196. St. Paul, MN: West Publishing Co.Trowell, H. C. and D. P. Burkitt

1981 Western Diseases: Their Emergence and Prevention. Cambridge, MA: Harvard Univ~rsityPress ..

Weiss, K. M., R. E. Ferrell, and C. 1. Harris1984 A New World Syndrome on Metabolic Diseases with a Genetic and Evolutionary Basis.

Yearbook of Physical Anthropology 27: 153-178.Weiss, K. M., J. S. Ulbrecht, P. R. Cavanaugh, and A. V. Buchanan

1989 Diabetes Mellitus in American Indians: Characteristics, Origins, and Preventive Health CareImplications. Medical Anthropology 11: 283-304.

Weiss, E. and O. S. English1949 Psychosomatic Medicine, Second Edition. Philadelphia, PA: W.B. Saunders and Co.

Whitt, H. P.1983 Status inconsistency: A body of negative evidence or a statistical artifact. Social Forces 62:

201-233.

II

!I

~I

sociocultural and behavioral influences on health ... · sociocultural and behavioral influences on...

Documents