Psychological Medicine, 1978, 8, 95-101 Printed in Great Britain

The relationship between psychological and physiological measures of anxiety GARY R. MORROW1 AND ANTHONY H. LABRUM From the University of Rochester Medical Center, Rochester, USA

The responses of 6 representative physiological parameters frequently assumed to be measures of anxiety along with a set of 4 psychological tests for measuring anxiety were obtained under naturalistic conditions from 25 patients hospitalized with a first myocardial infarction. A canonical correlational analysis failed to show any relationship between anxiety as assessed by the Taylor Manifest Anxiety Scale, Mood Adjective Check List, State-Trait Anxiety Inventory and Multiple Affect Adjective Check List psychological tests, and anxiety as assessed by the physiological indices of heart rate, systolic and diastolic blood pressures, epinephrine, norepinephrine and VMA. The intercorrelation matrix revealed a significant positive pattern of relationships among all 4 psychological tests, a non-significant, positive pattern of relationships among the physiological indices, and a non-significant, negative pattern of relationships between the psychological and physiological measures. The absence of mood-specific physiological measures for anxiety, as measured by the psychological tests, supports previous theory and investigation and points to the inadvisability of assuming that studies on anxiety that use diverse physiological and psychological measures yield results that may be compared as though they were assessing a common mood. SYNOPSIS

claiming that there is an established relationship between physiological responses of the sympathetic nervous system and anxiety. Physiological and psychological measures often continue to be used in anxiety research as if they were interchangeable criterion measures. There appears to be the assumption that, since a psychological test or physiological parameter is called an anxiety measure, it must measure anxiety. As Sarason (1960), Levitt (1967), Pichot (1971) and Tyrer & Lader (1976) have pointed out, attempts to assess the relationships among psychological and physiological measures of anxiety have proved largely inconclusive. Although many possible explanations for conflicting results have been offered, criticisms appear to t e directed largely at areas of contrived experimental manipulation (Izard, 1972), and inappropriate statistical analyses (Cattell, 1972). Variations in a subject's individual response to an experimental situation assumed to elicit anxiety have been pointed to as one potential source of conflicting results. Previous work by Allport (1924) and Tomkins (1962) supports this

INTRODUCTION Over the years, 2 principal methods have been used by most investigators to assess what is commonly referred to as anxiety. The first of these comprises a number of paper-and-pencil selfreport instruments grouped loosely under the term psychological measures or tests. Since the Taylor Manifest Anxiety Scale was published (Taylor, 1953), many psychological tests have been developed which claim to measure anxiety. The second method is the measurement of physiologically based indices of anxiety. The idea that a relationship exists between the mood labelled anxiety and various physiological effects related to the mood can be traced as far back as the observations of Aristotle (Foster & Humphries, 1951). The first orderly scientific investigations along this line were carried out by Cannon in the 1920s (Cannon, 1953). Subsequent research has been summarized by Froberg et al. (1971) 1 Address for correspondence: Dr Gary R. Morrow, Medical Psychiatric Liaison Group, Department of Psychiatry, University of Rochester Medical Center, 300 Crittenden Blvd, Rochester, NY 14642, USA.

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contention that few, if any, contrived laboratory situations can credibly elicit anxiety in all subjects. Previous assessments of the relationships between various anxiety measures have employed simple correlations between various measures (Levitt, 1967). This bivariate approach has been criticized (Izard, 1972; Cattell, 1972) largely on the basis that it is ineffective, uneconomical and and unable to provide the answers as to how more than 2 measures are related. The present multivariate study of patients with an acute onset of a disease was designed to overcome these 2 main areas of criticism and concern by employing a more realistic assessment methodology than previous studies, along with more appropriate statistical analyses of the data. METHOD Subjects Twenty-five patients admitted to a large metropolitan hospital with the diagnosis of a first myocardial infarction were studied. There were 19 males and 6 females ranging in age from 38 to 70, with a median age of 50 years. The average severity of the subjects' myocardial infarctions on a 5-point scale was 2-83 (S.D. = 1-09). The rating for each individual patient was made independently by 2 physicians who had treated the patient, and was based on the hospital course, enzyme count and any complications of treatment. Subjects were ambulant, with no indication of congestive heart failure at the time of assessment.

the subject in a real-life situation free of the manipulation usually associated with laboratories. The aim is to find a real-life circumstance or setting that is anticipated to evoke the desired response and then carry out the measurement process in that environment. Operationalized in terms of this study, the naturalistic method took the form of employing a hospital for the environmental setting. Unlike the vast majority of past investigations, no experimentally designed situation was employed to induce anxiety. Rather, the naturally occurring anxiety resulting from a subject's recent heart attack was employed (Miller, 1965).1 By having the subjects in a controlled environment for a much longer period of time than in past studies, it was felt that possible effects due to transient situational events were controlled to a high degree, leaving only the naturally occurring reaction to the myocardial infarction as an effect of long duration. Measurements of the physiological variables were made during a 24-hour period between the 10th and 12th day following admission into the hospital, largely depending on the laboratory schedule. This waiting period was based on the premise that subjects had been removed from intensive care and had time to acclimatize to the routine and environment of their immediate surroundings, thus removing any short-term, anxiety-provoking, experimental effect such as had been shown to confound many previous anxiety measurement studies (Levitt, 1967).

Physiological measures Procedure Prior permission was obtained from private cardiologists to obtain data from their hospitalized patients. A promising alternative approach to the contrived, laboratory-manipulated, experimental setting so often criticized is the naturalistic or 'non-reactive' approach to experimentation advocated by Barker (1969), Willems (1969), Sechrest (1969), and applied to the clinical area by Raush (1969). In place of artificially devising a situation in the laboratory where the subject is manipulated to elicit a presumably representative response, i.e. anxiety, the naturalistic approach calls for the observation of

Physiological measures of anxiety were selected on the basis of widespread use by previous investigators, along with demonstrated reliability and validity. Based on these criteria the following 6 physiological measures of anxiety were chosen: the urinary catecholamines epinephrine, norepinephrine and vanillymandelic acid (VMA); and the cardiovascular measures systolic and diastolic arterial blood pressure, and heart rate. Euler & Lundberg (1954) were among the first 1 The mean State-Trait Anxiety Inventory score for the subjects in the present study was in the 81st percentile compared with a normal population, thus supporting the assumption that they were above average in terms of being anxious.

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investigators to report an association between Anxiety Inventory, STAI (Spielberger, 1966; catecholamines and anxiety in a study comparing O'Neill et al. 1969), Multiple Affect Adjective epinephrine levels of pilots on days when they Check List, MA ACL (Zuckerman & Biase, 1962; flew as contrasted to non-flying days. Further Hankoff et al. 1962), and Mood Adjective Check associations between epinephrine, norepine- List, MACL (Nowlis & Green, 1965) were phrine, VMA and anxiety have been reported by selected. Levi (1963), Jones et al. (1968) and Gusova Due to the physical limitations of the subject, (1969). Deane & Zeaman (1958) have pointed the psychological instruments were designed to out that the use of heart rate as a physiological be administered in as short a time as feasible measure of anxiety has been established in a without sacrificing reliability. For this reason, the sizeable number of studies under a variety of Bendig (1956) short form of the Taylor Manifest experimental situations. As with heart rate, both Anxiety Scale (TMAS) was used along with systolic and diastolic blood pressure have con- abbreviated versions of the Multiple Affect sistently been used as indices of physiologically Adjective Check List (MAACL). Since even the measured anxiety (Lorimer et al. 1971; Gotts- condition of knowing that a psychological test is chalk & Gleser, 1969). being taken can affect subject's anxiety level Epinephrine, norepinephrine and vanillyman- (Levitt, 1967), the 4 psychological tests were delic acid (VMA) analyses were carried out on a presented as part of a routine hospital practice 24-hour urine sample from each subject employ- designed to improve service by asking a patient's ing the Crout Fluorometric and Standard Coloro- reaction to his stay. The TMAS had questions metric Methods as described by Weil-Malherbe along this line and was administered first. The (1968). Reliabilities in the range 0-83-0-94 have psychological instruments were administered been reported for these analyses (Crout, 1961; during midday of the urine collection period, so Sunderman, 1970). The 24-hour period was a common time base was established. selected to control for the normally occurring diurnal variation in these catecholamines. Fortyeight hours prior to the collection period, a Statistical method subject was placed on a special diet to control Two complementary multivariate statistical techdietary factors that could influence the analyses. niques were applied to the data in order to assess Special instruction sheets were prepared for the the relationship(s) between the psychological and attending private physician, alerting him to cer- physiological measures employed. The first of tain drugs such as epinephrine, norepinephrine, these was canonical correlational analysis, which methyldopa and isoproterenol, that could affect by revealing the linear combinations of one set physiological and biochemical assessments and of" variables that are most highly correlated with requesting that he refrain, if possible, from the linear combinations of the other set, permits administering them. (When such drugs were a robust examination of the relationship which required, and given, the subject was dropped from might exist between the 2 sets of variables the study.) Systolic blood pressure, diastolic (Tatsuoka, 1971; Cooley & Lohnes, 1971). As blood pressure, along with heart rate were taken applied to the data, the 4 psychological variables for each subject by staff nurses as part of normal were considered as one set and the 6 physiological ward procedure and averaged over the same variables as the other. 24-hour period as the urine sample. The second multivariate approach used was factor analysis. Bartlett (1948) has pointed out that canonical correlation can be considered an Psychological measures external factor analysis since individual variables As with the physiological measures, the psycho- are combined into sets for analysis, whereas the logical measures were selected on the basis of technique of factor analysis can be viewed as previous use and their established reliability and internal factor analysis since the variables are validity in the field of anxiety research. The each examined separately. Taylor Manifest Anxiety Scale, TMAS (Taylor, The canonical correlation, then, was used to 1953; Rychlak & Lerner, 1965), State-Trait test the degree of relationship between the 6 PRM 8

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Table 1. Correlation coefficients and distribution statistics, psychological and physiological measures (N = 25) Variables Psychological 1. TMAS 2. MACL 3. STAI 4. MAACL Physiological 5. Heart rate 6. Systolic blood pressure 7. Diastolic blood pressure 8. Epinephrine 9. Norepinephrine 10. Vanillymandelic acid (VMA)

1 100 0-73** 0-70" 0-73** 010 013 -018 -006 -0-32 010

2 — 100 0-93" 0-88" -001 000 -016 -010 -0-24 -0-35

4

5

6

7

8

9

10

— — — 100

— — — —

— — — —

— — — —

— — — —

— — — —

— — — —

-005 -007 008 017 011 -003 -017 -014 -0-34 -0-27 0-39* 0-26

100 000 -004 0-23 -005 -014

3 — — 100 0-95**

• P 0-5). Correlations among individual measures

Table 1, which gives the pair-wise Pearson product-moment correlation coefficients among the variables,1 provides for further analysis of the results. Where the canonical correlation focused on the various measures only in terms of two sets (i.e. physiological and psychological) and how these 2 sets were related, the individual correlations among all variables focus on the 1 When interpreting the correlational results of the study it is important to keep in mind that 'between subjects' correlations are presented. 'Within subjects' correlations dealing with physiological measures are sometimes reported to be higher than 'between subjects' correlations, presumably due to idiosyncratic factors such as physiological response specificity. For the present study, a' between subjects' methodology was seen as the more conservative approach.

— — 100 — 0-60** 100 0-23 -015 013 000 025 0-46*

— — — 100 007 018

— — — — 100 0-52"

— — — — 100

•* P < 0 0 1 .

relationships among all variables without grouping them into sets before the analysis. The intercorrelations among the 4 psychological measures are high (mean r = 0-85)2 and statistically significant (P < 001). Previous studies employing various populations have yielded significant correlations, although not always as high as reported here. Zuckerman & Biase (1962) reported rs from 0-58 to 0-69 between the MAACL and TMAS. Spielberger (1966) reported r = 0-80 between the STAI and TMAS and r = 0-52 between the STAI and MACL. As the STAI utilized the TMAS as one of the 3 component tests from which it was evolved, high intercorrelations are to be expected. The very high correlations between the MACL and the other 3 measures have little basis for comparison, since few comparative studies have been published using this instrument. The high correlations with the other 3 psychological tests were viewed as support for Nowlis & Green's (1965) interpretation that the section of the MAACL used here (Factor II) can be viewed as measuring anxiety. In contrast to the significant relationships found among the psychological measures, only 3 of the 15 pair-wise correlations among the 6 physiological measures demonstrated non-chance relationships. The anticipated significant relationship between systolic and diastolic blood pressure was demonstrated (r = 0-60, P < 0-01). A relationship between VMA and diastolic blood pressure was also found (r = 0-46, P < 005). 1

Fisher's r to Z transformation was used.

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Table 2. Factor structure, psychological and physiological measures (N = 25) Factor Psychological variables 1. TMAS 2. MACL 3. STAI 4. MAACL Physiological variables 5. Heart rate 6. Systolic blood pressure 7. Diastolic blood pressure 8. Epinephrine 9. Norepinephrine 10. Vanillymandelic acid (VMA)

I

II

III

IV

0-85 0-94 0-94 0-95

001 -011 -002 007

-007 -012 -0-22 -011

011 -004 -011 010

-003 013 -013 -004 -019 -019

-004 0-88 0-89 005 -017 0-43

-0-23 000 007 0-23 0-86 079

0-71 0-20 -0-20 0-82 -002 001

In general, however, the pattern of intercorrelations among the physiological measures was quite low (mean r = 0 1 5 ) - a finding consistent with previous studies (Bond et al. 1974; Tyrer & Lader, 1976). These results provide support for the contention that' no physiological measurement is an unambiguous measure of anxiety' (Lader, 1972, p. 485). Thus, while the psychological test variables were found to be highly interrelated, the physiological variables generally were not significantly related to either one another or the psychological test variables. Factor analysis The next step in the multivariate approach was a principal component factor analysis with a Kaiser varimax orthogonal rotation (Tatsuoka, 1971). This technique may be thought of as a statistical method of data reduction, whereby a relatively large set of correlated variables (such as Table 1) are reduced to a smaller number of underlying dimensions called factors. The factors produced by the analysis then represent basic categories or ways the variables group together. Four factors, accounting for 82 % of the total variance, were extracted from the analysis. They are presented in Table 2 along with the factor loadings for each variable on each of the 4 factors. The factor loading is essentially the correlation between a variable and the factor. Thus, in Table 2, the Taylor Manifest Anxiety Scale (TMAS) had factor loadings of 0-85, - 0 0 1 , - 0 0 7 and O i l on Factors I, II, III and IV respectively. The highest factor loading (i.e. that factor to which the variable demonstrated the strongest association) for each variable is in italics. Those

factor loadings italicized under a given factor then represent variables associated with that factor - variables found to group together. For example, the column of factor loadings shows that 2 variables (systolic blood pressure and diastolic blood pressure) were significantly associated (0-88 and 0-89 respectively) with Factor II and thus were themselves related to each other along some common dimension. Factor I (38 % of total variance) was viewed as a general factor for the psychological tests. Clearly, whatever is being measured by these 4 psychological tests is measured quite specifically by all 4, as indicated by the consistently high factor loadings. In view of the fact that these tests required the subjects to report perceptions of his mood, this factor may be seen as representing cpgnitively perceived anxiety. That is to say, the words or labels the subject uses to describe his understanding of the mood he experiences as anxiety. Factor II (19 % of total variance) was interpreted as a group factor for blood pressures as both systolic and diastolic blood pressure variables had high loadings on this factor. Factor 111(13 % of total variance) was a group factor for norepinephrine and VMA. As VMA is a metabolized end-product of both epinephrine and norepinephrine, the finding that these catecholamines loaded on different factors was unexpected. Factor IV (II % of total variance) was a group factor for epinephrine and heart rate. As Deane & Zeaman (1958) point out, many studies have concluded that heart rate is not only related to anxiety but is also highly correlated with both systolic and diastolic blood pressures. The reason 7-2

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for this divergent finding is not apparent, especially in view of the expected finding of a close relationship between systolic and diastolic pressures (Factor II). This phase of the analysis provided additional support for the contention that there was little or no relationship between what was being measured by the psychological tests and what the physiological indices were measuring. This is not to say, however, that one variable or group of variables is a superior measurement of anxiety to another, but rather that the psychological variables were found to be highly inter-related while physiological variables were not. And that, furthermore, psychological and physiological variables were not found to be highly inter-related when considered either as groups of variables by canonical correlation or individual variables by pair-wise correlations and factor analysis. An implication of these results is that a greater degree of confidence may be warranted when comparing the results of anxiety studies using psychological measures with other anxiety studies using psychological measures than when comparing anxiety studies using physiological measures with other anxiety studies using physiological measures, or other anxiety studies using psychological measures. Unresolved by the study is the issue of whether or not the various measures used here may be tapping different aspects of what must be viewed as a multi-faceted emotion. These findings may be considered as lending support to previous theoretical contentions. Lader (1972) presents a model of emotion within which he considers 'emotional feeling' a derivative of the individual's cognitive appraisal of threat and that the 'emotional feeling' both modifies and is modified by peripheral physiological changes. He points out that physiological changes usually occur as a result of emotions but that there is a wide variation of response dependent on the individual's previous experience and the possibility that differential feedback can occur depending on variations of awareness of peripheral autonomic changes. Bartorelli et al. (1960) demonstrated that increased heart rate and blood pressure may lead to EEG changes associated with cerebral cortical intubation. Lacey & Lacey (1958) discussed the possible effects of other afferent autonomic stimuli on the brain. They suggested that temporary hypertension and

tachycardia may be an attempt to produce a stimulus barrier and 'calm down' a state of cognitively perceived 'anxiety' or turmoil. This could, then, theoretically lead to an inverse relationship or no recognizable relationship between physiological arousal and psychologically perceived arousal. These results, in concert with the work of others such as Cattell (1972), Bond et al. (1974) and Tyrer & Lader (1976), point to the absence of mood-specific physiological indices of anxiety and bring into question the validity and advisability of assuming that studies on anxiety that use diverse physiological and psychological measures yield results that may be compared as though they were assessing a common mood. REFERENCES Allport, F. H. (1924). Social Psychology. Houghton-Mifflin: Cambridge, Mass. Barker, R. G. (1969). Wanted: an eco-behavioral science. In Naturalistic Viewpoints in Psychological Research (ed. E. P. Willems and H. L. Raush), pp. 31-42. Holt, Rinehart & Winston: New York. Bartlett, M. S. (1948). Internal and external factor analysis. British Journal of Psychology (Statistics Section) 1, 73-81. Bartorelli, C , Bizzi, E., Libretti, A. & Zanchetti, A. (1960). Inhibitory control of sinocarotid pressor receptive afferents on hypothalamic autonomic activity and sham rage. Archives of Italian Biology 48, 308-326. Bendig, A. W. (1956). The development of a short form of the manifest anxiety scale. Journal of Consulting Psychology 20, 384. Bond, A. J., James, D. C. & Lader, M. H. (1974). Physiological and psychological measures in anxious patients. Psychological Medicine 4, 364-373. Cannon, W. (1953). Bodily Changes in Pain, Hunger, Fear and Rage (2nd edn). Charles T. Branford: Boston. Cattell, R. B. (1972). The nature and genesis of mood states. In Anxiety: Current Trends in Theory and Research (ed. C. D. Spielberger), pp. 115-183. Academic Press: New York. Cooley, W. W. & Lohnes, P. R. (1971). Multivariate Data Analysis. Wiley: New York. Crout, J. R. (1961). Catecholamines in urine. Standard Method of Clinical Chemistry 3, 62-80. Deane, G. E. & Zeaman, D. (1958). Human heart rate during anxiety. Perceptual and Motor Skills 8, 103-106. Euler, V. S. & Lundberg, U. (1954). Effect of flying on the epinephrine excretion in Air Force personnel. Journal of Applied Psychology 6, 551. Foster, K. & Humphries, S. (1951). Translation of Aristotle's De Anima. Yale University Press: New Haven. Froberg, J., Karlsson, C , Levi, L. & Lindberg, L. (1971). Physiological and biochemical stress reactions induced by psychosocial stimuli. In Society, Stress and Disease vol. 1 (ed. L. Levi), pp. 280-299. Oxford University Press: New York. Gottschalk. L. A. & Gleser, G. C. (1969). The Measurement of Psychological States Through the Content Analysis of Verbal Behaviour. University of California Press: Berkeley. Gusova, A. B. (1969). Nekotorye klinikofiziologicheskie osobennosti anksioznykh sostoyanil. Zhurnal Neuropatologii i Psikhiatrii 69 (3), 390-396.

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Research (ed. E. P. Willems and H. L. Raush), pp. 122146. Holt, Rinehart & Winston: New York. Rychlak, J. F. & Lerner, J. J. (1965). An expectancy interpretation of manifest anxiety. Journal of Personality and Social Psychology 2, 677-684. Sarason, I. G. (I960). Empirical findings and theoretical problems in the use of anxiety scales. Psychological Reports 57(5), 403-415. Sechrest, L. (1969). Nonreactive assessment of attitudes. In Naturalistic Viewpoints in Psychological Research (ed. E. P. Willems and H. L. Raush), pp. 147-160. Holt, Rinehart & Winston: New York. Spielberger, C. D. (ed.) (1966). Anxiety and Behavior. Academic Press: New York. Sunderman, F. W. (1970). Colorimetric determination of vanillymandelic acid in urine. Clinical Chemistry 6,99-106. Tatsuoka, M. M. (1971). Multivariate Analysis: Techniques for Educational and Psychological Research. Wiley: New York. Taylor, J. A. (1953). A personality scale of manifest anxiety. Journal of Abnormal and Social Psychology 48, 285-290. Tomkins, S. S. (1962). Affect, Imagery, Consciousness. Vol. 1: The Positive Affects. Springer: New York. Tyrer, P. J. & Lader, M. H. (1976). Central and peripheral correlates of anxiety: a comparative study. Journal of Nervous and Mental Disease 162, 99-104. Weil-Malherbe, H. (1968). The estimation of total (free plus conjugated) catecholamines and some catecholamine metabolites in human urine. Methods of Biochemical Analysis 16, 293-326. Willems, E. P. (1969). Planning a rationale for naturalistic research. In Naturalistic Viewpoints in Psychological Research (ed. E. P. Willems and H. L. Raush), pp. 44-68. Holt, Rinehart & Winston: New York. Zuckerman, M. & Biase, D. W. (1962). Replication and further data on the validity of the affect adjective check list measure of anxiety. Journal of Consulting Psychology

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The relationship between psychological and physiological measures of anxiety.

Psychological Medicine, 1978, 8, 95-101 Printed in Great Britain The relationship between psychological and physiological measures of anxiety GARY R...
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