Journal of Gerontology 1979, Vol. 34, No. 6, 841-851
Stress and Adaptation in Later Life1 Erdman Palmore, PhD, William P. Cleveland, PhD, John B. Nowlin, MD, Dietolf Ramm, PhD, and Ilene C. Siegler, PhD2
HERE is now a vast multidisciplinary A literature concerned with stress research. The work of Cannon, Meyer, and Selye has led to an interest in life events as potential stresses in the development of physical and mental illness (Dohrenwend & Dohrenwend, 1974; Hultsch & Plemons, in press; Lowenthal et al., 1975; Timiras, 1972). Many studies have focused on the response to particular events: for example, retirement (Sheppard, 1976; Streib & Schneider, 1971); widowhood (Lopata, 1975); and the empty nest (Lowenthal & Chiriboga, 1972). Major medical and psychiatric events have been studied both as events requiring adaptation (Hamburg, et al., 1976; House, 1974; Pearlin & Schooler, 1978) and as indices of adaptation in response to combinations of other major life events (Rabkin & Struening, 1976). Various models of adaptation in late life have been proposed (House, 1974; Kuhlen, 1959; Lieberman, 1975; Lowenthal et al., 1975; Pearlin & Schooler, 1978). The various models have in common an emphasis on the multiple determinants of adaptation to stress and the importance of physical, psychological and social resources as mediating variables which affect the level of adaptation to the stressful event. We will view adaptation as the outcome of attempts to use various resources to cope with the stresses of life events. 'This paper is based on a symposium at the Annual Meeting of the Gerontological Society, Nov., 1977, San Francisco. The research was supported by Grant AG-00364, N1A, USPHS. ^Senior Fellows, Ctr. for the Study of Aging and Human Development, Box 3003, Duke Medical D r . , Durham, NC 27710.
Evaluation of stress-illness association has been, of necessity, piecemeal since data sets purporting to examine the relationship usually are not sufficiently broad-based to include all relevant individual attributes and responses to life events (Eisdorfer & Wilkie, 1977). Coronary heart disease has been associated with stress in several studies (Rosenman et al., 1970; Rosenman, 1974). While there have been attempts to link numerous other illnesses with stress, definitive work to substantiate these impressions is largely lacking. Multiple life events have been correlated with the advent of illness (Holmes & Masuda, 1974). However, the association is not strong and the life event scale itself provides a host of methodologic problems (Rabkin & Streuning, 1976). Much of previous research and writing about life-events and social-psychological adaptation has had a crisis orientation. This orientation assumes that major life events in later life such as retirement, widowhood, and serious illness usually produce great stress and often, if not typically, result in negative outcomes such as unhappiness, loss of self-esteem, withdrawal, and general decline (Butler, 1975; Datan & Ginsberg, 1975; Rosow, 1973, 1974). On the other hand, some have viewed these life events as potentially stressful but typically resulting in positive readjustment and new growth (Gould, 1978; Maas & Kuypers, 1974). Since studies of social-psychological adaptation have typically been tied to one particular event, we will briefly consider the literature on each event separately. 841
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The effects of five major life events, and of three types of resources, on the physical and socialpsychological adaptation of 375 participants in a longitudinal study were examined. As expected, medical events had the most impact on physical adaptation, but they had surprisingly little impact on social-psychological adaptation. Retirement had the most negative social-psychological effects, but had little effect on physical adaptation. The other three events had even less effects, although multiple events tended to cumulate in impact. Better physical resources helped only physical adaptation, and better psychological and social resources mainly helped satisfaction. It appears that most of these potential stressors have less serious long-term outcomes than the crisis orientation would suggest.
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STRESS AND ADAPTATION
tudinal Study provides a unique opportunity to analyze such problems because it has measures of adaptation before and after the occurrence of these events as well as the same measures for comparable groups who did not experience the events. METHOD
Sample. — The data were collected as part of the Second Longitudinal Study conducted by the Duke Ctr. for the Study of Aging and Human Development (Palmore, 1974). A probability sample, stratified by age and sex, was drawn from the membership list of the major health insurance association in Durham County, NC. Ten age-sex cohorts were defined of approximately equal size and representing five-year intervals between the ages of 45 and 70 in 1968. The membership list from which the sample was drawn included the majority of white, middle and upper income level Durham residents. Black, as well as disabled, illiterate, and institutionalized persons were excluded. Lower socioeconomic persons were significantly under-represented. There was a refusal rate of 52%, but an analysis of differences between the refusers and participants found little significant difference in terms of demographic characteristics, socioeconomic status, and health (Palmore, 1974). Data was collected at four points in time between 1,968 and 1976 (with two years between each round of examinations). There were 502 subjects at the beginning of the study, but the present analysis is based on the 375 who returned for the fourth and final round of examinations. An analysis of drop-outs indicates that they tended to have somewhat lower health, psychological, and social resources than the 375 who did not drop out but that there was otherwise little significant difference between the drop-outs and the returners. Events. — The events chosen for study were five major events commonly related to transitions in middle and later life: subject's retirement, spouses' retirement, widowhood, departure of last child from home, and major medical event (occurrence of an illness severe enough to require hospitalization). All event variables were dichotomous except for medical events, which could range from zero to three
Downloaded from http://geronj.oxfordjournals.org/ at University of Michigan on September 9, 2015
Most of the crisis orientation literature has emphasized the problems of adapting to retire-" ment and its negative effects on satisfaction, self-esteem, and activity (Atchley, 1971). On the other hand, Streib and Schneider (1971) found little or no evidence of such detrimental effects. As for spouse's retirement, the Duke First Longitudinal Study found that more than onehalf of the wives of retirees were sorry that their husbands retired, especially if they were from the lower socioeconomic group (Heyman & Jeffers, 1968). An earlier Duke study also found that wives of retirees report less satisfaction than their retiring husbands (Kerckhoff, 1964). Previous research relevant to medical events has shown that health is strongly related to life satisfaction and to other measures of adaptation in later life (Palmore, 1974). Therefore, it seemed reasonable to hypothesize that the occurrence of major illness would cause substantial declines in our indicators of adaptation. Many people believe that widowhood is the most disruptive life event (Parkes, 1973). The Holmes and Rahe schedule of life events rates "death of spouse" as having a higher score than any other event in terms of seriousness of effect (Holmes & Rahe, 1967). However, the Duke First Longitudinal Study found little or no long-term detrimental effects on those widowed during the study (Heyman & Gianturco, 1973). Departure of last child from home is so often believed to be problematic by the public, clinicians, and some researchers that there is a common term for these problems: the "empty nest" syndrome (Lowenthal & Chiriboga, 1972). However, Glenn (1975) concluded that children leaving home does not typically have an enduring negative effect. This paper analyzes the physical, psychological, and social adaptation to five common life events in later life; retirement, spouse's retirement, major medical events, widowhood, and departure of last child from home. These events were chosen both because they are so common and because there is considerable controversy about the difficulty of adapting to them. The paper also analyzes physical, psychological, and social resources as potential mediators which facilitate adaptation to these life events. The Duke Second Longi-
PALMORE, CLEVELAND, NOWLIN, RAMM AND SIEGLER
Resources. — Because of space limitations the conceptualization and measurement of the resources analyzed will be described briefly. More information on details of measurement and scoring may be obtained from the authors on request. Health resources were defined in terms of functional ability and were measured by a single overall medical rating made during the first examination by the examining physician which could range from one for normal functional ability, to nine for totally disabled. However, no one was rated more than four because no one was severely disabled. Thirty-eight percent were rated one; 50% were rated two;
and 12% were rated three or four (low health resources). Psychological resources were defined as a combination of level of intellectual functioning measured by four subtests of the Wechsler Adult Intelligence Scale: Information, Vocabulary, Digit Symbol, and Picture Arrangement (Wechsler, 1955) and a personality factor named anxiety vs adjustment derived from the Cattell 16 PF Scale (Cattell et al., 1970). This combination resulted in a score classification of Low (42%), Middle (41%), and High (17%) psychological resources. Social resources were defined as a combination of income, educational attainment, and the density of the available social network such as spouse, children, relatives, friends, neighbors, and confidants. The two socioeconomic measures (income and education) were each scored to range from one to nine. Each of the six types of role partners were scored on a three-point scale with three representing greatest availability. Thus, the combined social resources scale could range from eight (one for each of two SES measures and one for each of six role partners) to 36 (nine for each of two SES measures and three for each of six role partners), and gives equal weight to the socioeocnomic variables and to the social network variables. The median social resources score was 28.
Table 1. Means and Standard Deviations for Adaptation Measures, Rounds 1 and 4 (N = 375). Means (SD) Round 1
Physical Measures 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
Cardiovascular system (CVR) Musculoskeletal System (MSR) Self-rated Health (SRH) Weight (WT) Systolic Blood Pressure (SBP) Diastolic Blood Pressure (DBP) Physician Visits/Year (MD VISITS) Regular Medications (MEDS) Weeks in Bed/Year (SICK TIME) Symptoms checked (CK-LIST)
Round 4
0.46 0.50 2.8 71.0 140.0 84.0 2.1 0.80 0.65 2.2
(0.83) (0.86) (0.71) (13.0) (22.0) (11.0) (2.3) (1.1) (1.5) (2.0)
0.43 0.67 2.9 71.0 127.0 71.0 2.7 1.1 0.67 2.0
(0.77) (0.93) (0.67) (13.0) (18.0) (12.0) (2.7) (1.3) (1.7) (2.0)
7.0 1.1 3.7 5.5 2.1 9.8 64.0
(1.4) (2.8) (3.8) (0.95) (0.97) (6.0) (17.0)
7.0 2.9 3.1 5.4 1.9 9.3 56.0
(1.4) (3.5) (3.6) (1.0) (0.96) (7.3) (20.0)
Social-Psychological Measures 1. 2. 3. 4. 5. 6. 7.
Life Satisfaction Affect Balance Psychosomatic Symptoms Feeling Useful Feeling Respected Social Hours/Week Active Hours/Week
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depending on how many periods contained a medical event. Thus, total events could range from zero to seven. The number of persons experiencing each event during the study were: retirement, 78; spouse's retirement, 78; widowhood, 25; departure of last child, 57; and major medical event, 92. The number of persons eligible for each event who did not experience the event were: retirement, 154; spouse's retirement, 170; widowhood, 293; departure of last child, 55; and major medical event, 283. There were a total of 238 persons who experienced one or more events during the study.
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ADAPTATION MEASURES
Table 1 presents the means and standard deviations for all adaptation measures at Rounds one and four, to indicate their levels and overall stability over time.
1965). In contrast to this global measure of life satisfaction, the Affect Balance Scale focuses on four positive and four negative emotions experienced during the past week (Bradburn & Caplovitz, 1965). The third measure of satisfaction was an indirect one, based on the frequency during the last week of nine psychosomatic symptoms such as headaches, nervousness, and sleeplessness (Leighton, 1963).
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Physical. — The first category of physical adaptation measures included three health ratings. The Cardiovascular System Rating was based upon history taking, physical examination, and laboratory data; the examining Self-esteem. — Measured by two sets of physician rated each study participant on a adjectives from the semantic differential scale: zero to nine scale for the extent of cardiovascu- Respect and Useful. This scale asks the lar disease (zero representing no cardiovascu- respondents to describe how they really are lar disease and nine a near terminal state). The by marking a point on a seven-point scale Musculoskeletal System Rating used a similar between two polar opposites: "respected" vs procedure for rating the extent of disease or "not respected," "useful" vs "useless" injury-related joint and muscle incapacity. The (Palmcre, 1974). Self-Rated Health was the participant's own rating of his health, ranging from one for "poor Activity. — Measured by the number of leihealth" to four for "excellent health." sure Social Hours and the number of Active A second category included the direct mea- Hours engaged in during the last typical week. sures of weight, systolic and diastolic blood The Social Hours are an indicator of interpressure. The third category might be called personal relations and the Active Hours are illness behavior. This included number of an indicator of general activity. physician visits per year, number of medicaA correlation matrix of these seven socialtions taken on a regular basis, number of weeks psychological measures of adaptation (not spent in bed with illness per year, and number shown) demonstrated that, on the one hand, of responses on a. 30-item symptom checklist. each appeared to measure a separate aspect of adaptation because none of the correlations Social-psychological. — There is consider- are high (none over .43); but on the other hand, able agreement among researchers about the the measures within each of the three areas essential dimensions of social-psychological tended to be more highly correlated with each adaptation to stress. For example, Hamburg other than with the measures in the other two (1974) identified four requirements of adapta- areas. A factor analysis confirmed that there tion to stress: containment of distress within were indeed three factors corresponding to tolerable limits, maintenance of self-esteem, these three areas, and that these factors acpreservation of interpersonal relations, and counted for 65% of the total variance. About 2% of the values on the adaptation meeting the conditions of the new environment. Our measures of satisfaction, self- variables were missing due to incomplete quesesteem, and social activity are indicators of tionnaires or examinations. These missing the first three of these adaptation require- values were estimated by a program which ments. All the subjects in this analysis met the predicts the most likely value obtained from fourth requirement in that they survived and recursive linear regressions on all the other were able to participate in the fourth round variables (Orchard & Woodbury, 1972). of examinations. The general area of satisfaction is of primary ANALYSES importance in social-psychological adaptation. Two types of analysis were used for this We used three different indicators of satisfac- paper: regression of residualized change scores tion: life satisfaction, affect balance, and and repeated measures analysis of variance. psychosomatic symptoms. Life satisfaction Each method has some advantage over the was measured by the "Cantril Ladder", a ten- other. The use of alternative statistical procepoint scale ranging from zero ("worst possible dures gives a form of replication of findings life") to nine ("best possible life") (Cantril, which can be compared.
PALMORE, CLEVELAND, NOWLIN, RAMM AND SIEGLER
before and after an event. More subjects were measured during or near the unstable period. If an event had no effect, then all four points would follow the time effect. If an event did have an effect, then the multiple measures before and after the event would show the level and direction of effect. The disadvantage of this method was that it did not control for regression toward the mean effects. We analyzed both physical adaptation and social-psychological adaptation with both the residual change analysis and the repeated measures analysis; the results were basically similar. Since the physical adaptation measures are less likely to be biased by regression toward the mean we will present the results of the repeated measures analysis for the physical adaptation. This allows fuller use of all the data. However, for the social-psychological measures we will present the residual change analysis which nullifies the substantial regression toward the mean present in these measures. RESULTS
Physical adaptation. — The influence of the life events upon physical adaptation, as well as modification of this influence by resources, is presented in Table 2. This table shows the significant associations (p < .05) found in the 50 separate analyses of variance required for the five events and ten outcomes. For the significant associations between events and outcomes, a plus sign (+) indicates that event occurrence was associated with an increase in variable score, a minus sign (—) indicates a decrease. For the significant interaction effects of resources and events, a plus sign (+) indicates that "high" resource status accompanying the event was accompanied by a higher variable score; conversely, a minus sign (-) indicates a lower variable value with high resources in conjunction with an event. A review of Table 2 indicates that Major Medical Events were the events most likely to be followed by statistically significant change toward poor health, as might be expected. However, it is noteworthy that participants with high resources tended to have less change following a Major Medical Event. For example, the self-rated health showed significant decreases after a Major Medical Event;
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A dominant feature of any longitudinal study is that subjects tend to preserve their rank order on any measure. It is the deviations from this expectation, or the residual change, which requires explanation. Not so evident is the fact that changes tend to be negatively correlated with initial values. Since the data contain some "noise," or unexplainable random variation, persons with initially low values will tend to show larger than average increases, while those with initially high values will tend to show larger than average decreases; a tendency known as "regression toward the mean". To control for this tendency, residual change analysis uses a special form of a regression model to analyze the factors related to change after initial scores are controlled. It nullifies the negative correlation of changes with initial values ("regression toward the mean") by entering the intitial score on an outcome variable as the first independent variable, leaving only residual change to be explained by the other variables. A discussion of this method appears in Cronbach and Furby (1970). The presence of a control group (who were eligible for an event, but did not experience it) means that the effects of the event on the residual changes are relative to changes in an event-free group. The main question answered by residual change analysis is, what are the effects of the events and resources on adaptation when initial level of adaptation is taken into account? In repeated measures analysis, the values for the dependent variable at each of the four rounds were treated as the response. Since more than one measure might occur before or after an event, a more precise measure of responses surrounding an event for each subject was available. However, it was necessary to adjust for secular time effects. The analysis differed from traditional repeated measures analysis of variance in that occurrence of an event was represented by a step function occurring in the interval of the event (Winer, 1971). Adjustment for resource levels was accomplished by dividing the population into resource groups. Adjustment for the pattern that would have occurred in the absence of an event was made by estimating a time effect for all subjects (with and without events). The advantage of this method was that it used all the available data (at four points in time), which include the measures immediately
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STRESS AND ADAPTATION
Table 2. Effects of Life Events, Resources Upon Selected Health Variables — Results of Repeated Measures Analysis. CVR Major Medical Event Event Event-HR Interaction Event-SR Interaction Event-PR Interaction
MSR
SRH
+(**) -(**)
+(**) -(*) _(***)
+(*)
-(**)
-(**)
+O
SBP
DPB
+(***) -(*)
(**)
-(**) +(**)
(*)
MD VISITS
-(*)
-(**)
MEDS
+(***) +(***) -(*) -(***)
SICK TIME
Symptom CK-LIST
+(***) -(***)
+( ***) - ( ***)
-(*)
(*) +(**)
-(*)
Widowhood Event Event-HR Interaction Event-SR Interaction Event-PR Interaction
+(*)
+(*) -(**) -(•*)
Retirement Event Event-HR Interaction Event-SR Interaction Event-PR Interaction Spouse Retirement Event Event-HR Interaction Event-SR Interaction Event-PR Interaction
+(***)
-(*) +(**)
-(••)
(*)
-(*)
+(*) _(***)
*=p
Stress and Adaptation in Later Life1 Erdman Palmore, PhD, William P. Cleveland, PhD, John B. Nowlin, MD, Dietolf Ramm, PhD, and Ilene C. Siegler, PhD2
HERE is now a vast multidisciplinary A literature concerned with stress research. The work of Cannon, Meyer, and Selye has led to an interest in life events as potential stresses in the development of physical and mental illness (Dohrenwend & Dohrenwend, 1974; Hultsch & Plemons, in press; Lowenthal et al., 1975; Timiras, 1972). Many studies have focused on the response to particular events: for example, retirement (Sheppard, 1976; Streib & Schneider, 1971); widowhood (Lopata, 1975); and the empty nest (Lowenthal & Chiriboga, 1972). Major medical and psychiatric events have been studied both as events requiring adaptation (Hamburg, et al., 1976; House, 1974; Pearlin & Schooler, 1978) and as indices of adaptation in response to combinations of other major life events (Rabkin & Struening, 1976). Various models of adaptation in late life have been proposed (House, 1974; Kuhlen, 1959; Lieberman, 1975; Lowenthal et al., 1975; Pearlin & Schooler, 1978). The various models have in common an emphasis on the multiple determinants of adaptation to stress and the importance of physical, psychological and social resources as mediating variables which affect the level of adaptation to the stressful event. We will view adaptation as the outcome of attempts to use various resources to cope with the stresses of life events. 'This paper is based on a symposium at the Annual Meeting of the Gerontological Society, Nov., 1977, San Francisco. The research was supported by Grant AG-00364, N1A, USPHS. ^Senior Fellows, Ctr. for the Study of Aging and Human Development, Box 3003, Duke Medical D r . , Durham, NC 27710.
Evaluation of stress-illness association has been, of necessity, piecemeal since data sets purporting to examine the relationship usually are not sufficiently broad-based to include all relevant individual attributes and responses to life events (Eisdorfer & Wilkie, 1977). Coronary heart disease has been associated with stress in several studies (Rosenman et al., 1970; Rosenman, 1974). While there have been attempts to link numerous other illnesses with stress, definitive work to substantiate these impressions is largely lacking. Multiple life events have been correlated with the advent of illness (Holmes & Masuda, 1974). However, the association is not strong and the life event scale itself provides a host of methodologic problems (Rabkin & Streuning, 1976). Much of previous research and writing about life-events and social-psychological adaptation has had a crisis orientation. This orientation assumes that major life events in later life such as retirement, widowhood, and serious illness usually produce great stress and often, if not typically, result in negative outcomes such as unhappiness, loss of self-esteem, withdrawal, and general decline (Butler, 1975; Datan & Ginsberg, 1975; Rosow, 1973, 1974). On the other hand, some have viewed these life events as potentially stressful but typically resulting in positive readjustment and new growth (Gould, 1978; Maas & Kuypers, 1974). Since studies of social-psychological adaptation have typically been tied to one particular event, we will briefly consider the literature on each event separately. 841
Downloaded from http://geronj.oxfordjournals.org/ at University of Michigan on September 9, 2015
The effects of five major life events, and of three types of resources, on the physical and socialpsychological adaptation of 375 participants in a longitudinal study were examined. As expected, medical events had the most impact on physical adaptation, but they had surprisingly little impact on social-psychological adaptation. Retirement had the most negative social-psychological effects, but had little effect on physical adaptation. The other three events had even less effects, although multiple events tended to cumulate in impact. Better physical resources helped only physical adaptation, and better psychological and social resources mainly helped satisfaction. It appears that most of these potential stressors have less serious long-term outcomes than the crisis orientation would suggest.
842
STRESS AND ADAPTATION
tudinal Study provides a unique opportunity to analyze such problems because it has measures of adaptation before and after the occurrence of these events as well as the same measures for comparable groups who did not experience the events. METHOD
Sample. — The data were collected as part of the Second Longitudinal Study conducted by the Duke Ctr. for the Study of Aging and Human Development (Palmore, 1974). A probability sample, stratified by age and sex, was drawn from the membership list of the major health insurance association in Durham County, NC. Ten age-sex cohorts were defined of approximately equal size and representing five-year intervals between the ages of 45 and 70 in 1968. The membership list from which the sample was drawn included the majority of white, middle and upper income level Durham residents. Black, as well as disabled, illiterate, and institutionalized persons were excluded. Lower socioeconomic persons were significantly under-represented. There was a refusal rate of 52%, but an analysis of differences between the refusers and participants found little significant difference in terms of demographic characteristics, socioeconomic status, and health (Palmore, 1974). Data was collected at four points in time between 1,968 and 1976 (with two years between each round of examinations). There were 502 subjects at the beginning of the study, but the present analysis is based on the 375 who returned for the fourth and final round of examinations. An analysis of drop-outs indicates that they tended to have somewhat lower health, psychological, and social resources than the 375 who did not drop out but that there was otherwise little significant difference between the drop-outs and the returners. Events. — The events chosen for study were five major events commonly related to transitions in middle and later life: subject's retirement, spouses' retirement, widowhood, departure of last child from home, and major medical event (occurrence of an illness severe enough to require hospitalization). All event variables were dichotomous except for medical events, which could range from zero to three
Downloaded from http://geronj.oxfordjournals.org/ at University of Michigan on September 9, 2015
Most of the crisis orientation literature has emphasized the problems of adapting to retire-" ment and its negative effects on satisfaction, self-esteem, and activity (Atchley, 1971). On the other hand, Streib and Schneider (1971) found little or no evidence of such detrimental effects. As for spouse's retirement, the Duke First Longitudinal Study found that more than onehalf of the wives of retirees were sorry that their husbands retired, especially if they were from the lower socioeconomic group (Heyman & Jeffers, 1968). An earlier Duke study also found that wives of retirees report less satisfaction than their retiring husbands (Kerckhoff, 1964). Previous research relevant to medical events has shown that health is strongly related to life satisfaction and to other measures of adaptation in later life (Palmore, 1974). Therefore, it seemed reasonable to hypothesize that the occurrence of major illness would cause substantial declines in our indicators of adaptation. Many people believe that widowhood is the most disruptive life event (Parkes, 1973). The Holmes and Rahe schedule of life events rates "death of spouse" as having a higher score than any other event in terms of seriousness of effect (Holmes & Rahe, 1967). However, the Duke First Longitudinal Study found little or no long-term detrimental effects on those widowed during the study (Heyman & Gianturco, 1973). Departure of last child from home is so often believed to be problematic by the public, clinicians, and some researchers that there is a common term for these problems: the "empty nest" syndrome (Lowenthal & Chiriboga, 1972). However, Glenn (1975) concluded that children leaving home does not typically have an enduring negative effect. This paper analyzes the physical, psychological, and social adaptation to five common life events in later life; retirement, spouse's retirement, major medical events, widowhood, and departure of last child from home. These events were chosen both because they are so common and because there is considerable controversy about the difficulty of adapting to them. The paper also analyzes physical, psychological, and social resources as potential mediators which facilitate adaptation to these life events. The Duke Second Longi-
PALMORE, CLEVELAND, NOWLIN, RAMM AND SIEGLER
Resources. — Because of space limitations the conceptualization and measurement of the resources analyzed will be described briefly. More information on details of measurement and scoring may be obtained from the authors on request. Health resources were defined in terms of functional ability and were measured by a single overall medical rating made during the first examination by the examining physician which could range from one for normal functional ability, to nine for totally disabled. However, no one was rated more than four because no one was severely disabled. Thirty-eight percent were rated one; 50% were rated two;
and 12% were rated three or four (low health resources). Psychological resources were defined as a combination of level of intellectual functioning measured by four subtests of the Wechsler Adult Intelligence Scale: Information, Vocabulary, Digit Symbol, and Picture Arrangement (Wechsler, 1955) and a personality factor named anxiety vs adjustment derived from the Cattell 16 PF Scale (Cattell et al., 1970). This combination resulted in a score classification of Low (42%), Middle (41%), and High (17%) psychological resources. Social resources were defined as a combination of income, educational attainment, and the density of the available social network such as spouse, children, relatives, friends, neighbors, and confidants. The two socioeconomic measures (income and education) were each scored to range from one to nine. Each of the six types of role partners were scored on a three-point scale with three representing greatest availability. Thus, the combined social resources scale could range from eight (one for each of two SES measures and one for each of six role partners) to 36 (nine for each of two SES measures and three for each of six role partners), and gives equal weight to the socioeocnomic variables and to the social network variables. The median social resources score was 28.
Table 1. Means and Standard Deviations for Adaptation Measures, Rounds 1 and 4 (N = 375). Means (SD) Round 1
Physical Measures 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
Cardiovascular system (CVR) Musculoskeletal System (MSR) Self-rated Health (SRH) Weight (WT) Systolic Blood Pressure (SBP) Diastolic Blood Pressure (DBP) Physician Visits/Year (MD VISITS) Regular Medications (MEDS) Weeks in Bed/Year (SICK TIME) Symptoms checked (CK-LIST)
Round 4
0.46 0.50 2.8 71.0 140.0 84.0 2.1 0.80 0.65 2.2
(0.83) (0.86) (0.71) (13.0) (22.0) (11.0) (2.3) (1.1) (1.5) (2.0)
0.43 0.67 2.9 71.0 127.0 71.0 2.7 1.1 0.67 2.0
(0.77) (0.93) (0.67) (13.0) (18.0) (12.0) (2.7) (1.3) (1.7) (2.0)
7.0 1.1 3.7 5.5 2.1 9.8 64.0
(1.4) (2.8) (3.8) (0.95) (0.97) (6.0) (17.0)
7.0 2.9 3.1 5.4 1.9 9.3 56.0
(1.4) (3.5) (3.6) (1.0) (0.96) (7.3) (20.0)
Social-Psychological Measures 1. 2. 3. 4. 5. 6. 7.
Life Satisfaction Affect Balance Psychosomatic Symptoms Feeling Useful Feeling Respected Social Hours/Week Active Hours/Week
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depending on how many periods contained a medical event. Thus, total events could range from zero to seven. The number of persons experiencing each event during the study were: retirement, 78; spouse's retirement, 78; widowhood, 25; departure of last child, 57; and major medical event, 92. The number of persons eligible for each event who did not experience the event were: retirement, 154; spouse's retirement, 170; widowhood, 293; departure of last child, 55; and major medical event, 283. There were a total of 238 persons who experienced one or more events during the study.
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STRESS AND ADAPTATION
ADAPTATION MEASURES
Table 1 presents the means and standard deviations for all adaptation measures at Rounds one and four, to indicate their levels and overall stability over time.
1965). In contrast to this global measure of life satisfaction, the Affect Balance Scale focuses on four positive and four negative emotions experienced during the past week (Bradburn & Caplovitz, 1965). The third measure of satisfaction was an indirect one, based on the frequency during the last week of nine psychosomatic symptoms such as headaches, nervousness, and sleeplessness (Leighton, 1963).
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Physical. — The first category of physical adaptation measures included three health ratings. The Cardiovascular System Rating was based upon history taking, physical examination, and laboratory data; the examining Self-esteem. — Measured by two sets of physician rated each study participant on a adjectives from the semantic differential scale: zero to nine scale for the extent of cardiovascu- Respect and Useful. This scale asks the lar disease (zero representing no cardiovascu- respondents to describe how they really are lar disease and nine a near terminal state). The by marking a point on a seven-point scale Musculoskeletal System Rating used a similar between two polar opposites: "respected" vs procedure for rating the extent of disease or "not respected," "useful" vs "useless" injury-related joint and muscle incapacity. The (Palmcre, 1974). Self-Rated Health was the participant's own rating of his health, ranging from one for "poor Activity. — Measured by the number of leihealth" to four for "excellent health." sure Social Hours and the number of Active A second category included the direct mea- Hours engaged in during the last typical week. sures of weight, systolic and diastolic blood The Social Hours are an indicator of interpressure. The third category might be called personal relations and the Active Hours are illness behavior. This included number of an indicator of general activity. physician visits per year, number of medicaA correlation matrix of these seven socialtions taken on a regular basis, number of weeks psychological measures of adaptation (not spent in bed with illness per year, and number shown) demonstrated that, on the one hand, of responses on a. 30-item symptom checklist. each appeared to measure a separate aspect of adaptation because none of the correlations Social-psychological. — There is consider- are high (none over .43); but on the other hand, able agreement among researchers about the the measures within each of the three areas essential dimensions of social-psychological tended to be more highly correlated with each adaptation to stress. For example, Hamburg other than with the measures in the other two (1974) identified four requirements of adapta- areas. A factor analysis confirmed that there tion to stress: containment of distress within were indeed three factors corresponding to tolerable limits, maintenance of self-esteem, these three areas, and that these factors acpreservation of interpersonal relations, and counted for 65% of the total variance. About 2% of the values on the adaptation meeting the conditions of the new environment. Our measures of satisfaction, self- variables were missing due to incomplete quesesteem, and social activity are indicators of tionnaires or examinations. These missing the first three of these adaptation require- values were estimated by a program which ments. All the subjects in this analysis met the predicts the most likely value obtained from fourth requirement in that they survived and recursive linear regressions on all the other were able to participate in the fourth round variables (Orchard & Woodbury, 1972). of examinations. The general area of satisfaction is of primary ANALYSES importance in social-psychological adaptation. Two types of analysis were used for this We used three different indicators of satisfac- paper: regression of residualized change scores tion: life satisfaction, affect balance, and and repeated measures analysis of variance. psychosomatic symptoms. Life satisfaction Each method has some advantage over the was measured by the "Cantril Ladder", a ten- other. The use of alternative statistical procepoint scale ranging from zero ("worst possible dures gives a form of replication of findings life") to nine ("best possible life") (Cantril, which can be compared.
PALMORE, CLEVELAND, NOWLIN, RAMM AND SIEGLER
before and after an event. More subjects were measured during or near the unstable period. If an event had no effect, then all four points would follow the time effect. If an event did have an effect, then the multiple measures before and after the event would show the level and direction of effect. The disadvantage of this method was that it did not control for regression toward the mean effects. We analyzed both physical adaptation and social-psychological adaptation with both the residual change analysis and the repeated measures analysis; the results were basically similar. Since the physical adaptation measures are less likely to be biased by regression toward the mean we will present the results of the repeated measures analysis for the physical adaptation. This allows fuller use of all the data. However, for the social-psychological measures we will present the residual change analysis which nullifies the substantial regression toward the mean present in these measures. RESULTS
Physical adaptation. — The influence of the life events upon physical adaptation, as well as modification of this influence by resources, is presented in Table 2. This table shows the significant associations (p < .05) found in the 50 separate analyses of variance required for the five events and ten outcomes. For the significant associations between events and outcomes, a plus sign (+) indicates that event occurrence was associated with an increase in variable score, a minus sign (—) indicates a decrease. For the significant interaction effects of resources and events, a plus sign (+) indicates that "high" resource status accompanying the event was accompanied by a higher variable score; conversely, a minus sign (-) indicates a lower variable value with high resources in conjunction with an event. A review of Table 2 indicates that Major Medical Events were the events most likely to be followed by statistically significant change toward poor health, as might be expected. However, it is noteworthy that participants with high resources tended to have less change following a Major Medical Event. For example, the self-rated health showed significant decreases after a Major Medical Event;
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A dominant feature of any longitudinal study is that subjects tend to preserve their rank order on any measure. It is the deviations from this expectation, or the residual change, which requires explanation. Not so evident is the fact that changes tend to be negatively correlated with initial values. Since the data contain some "noise," or unexplainable random variation, persons with initially low values will tend to show larger than average increases, while those with initially high values will tend to show larger than average decreases; a tendency known as "regression toward the mean". To control for this tendency, residual change analysis uses a special form of a regression model to analyze the factors related to change after initial scores are controlled. It nullifies the negative correlation of changes with initial values ("regression toward the mean") by entering the intitial score on an outcome variable as the first independent variable, leaving only residual change to be explained by the other variables. A discussion of this method appears in Cronbach and Furby (1970). The presence of a control group (who were eligible for an event, but did not experience it) means that the effects of the event on the residual changes are relative to changes in an event-free group. The main question answered by residual change analysis is, what are the effects of the events and resources on adaptation when initial level of adaptation is taken into account? In repeated measures analysis, the values for the dependent variable at each of the four rounds were treated as the response. Since more than one measure might occur before or after an event, a more precise measure of responses surrounding an event for each subject was available. However, it was necessary to adjust for secular time effects. The analysis differed from traditional repeated measures analysis of variance in that occurrence of an event was represented by a step function occurring in the interval of the event (Winer, 1971). Adjustment for resource levels was accomplished by dividing the population into resource groups. Adjustment for the pattern that would have occurred in the absence of an event was made by estimating a time effect for all subjects (with and without events). The advantage of this method was that it used all the available data (at four points in time), which include the measures immediately
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STRESS AND ADAPTATION
Table 2. Effects of Life Events, Resources Upon Selected Health Variables — Results of Repeated Measures Analysis. CVR Major Medical Event Event Event-HR Interaction Event-SR Interaction Event-PR Interaction
MSR
SRH
+(**) -(**)
+(**) -(*) _(***)
+(*)
-(**)
-(**)
+O
SBP
DPB
+(***) -(*)
(**)
-(**) +(**)
(*)
MD VISITS
-(*)
-(**)
MEDS
+(***) +(***) -(*) -(***)
SICK TIME
Symptom CK-LIST
+(***) -(***)
+( ***) - ( ***)
-(*)
(*) +(**)
-(*)
Widowhood Event Event-HR Interaction Event-SR Interaction Event-PR Interaction
+(*)
+(*) -(**) -(•*)
Retirement Event Event-HR Interaction Event-SR Interaction Event-PR Interaction Spouse Retirement Event Event-HR Interaction Event-SR Interaction Event-PR Interaction
+(***)
-(*) +(**)
-(••)
(*)
-(*)
+(*) _(***)
*=p
![[Early-life stress and vulnerability for disease in later life].](/assets/img/hold.png)
