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MMPI performance among women with bulimia: A cluster-analytic study
Addictive Behaviors, Vol. 20, No. 1, pp. 137-140, 1995 Copyright 0 1995 Elsevier Science Ltd Printed in the USA. All rights reserved 0306-4603195 $9.50 + .OO
Pergamon
BRIEF REPORT MMPI PERFORMANCE AMONG WOMEN WITH BULIMIA: A CLUSTER-ANALYTIC STUDY DONALD
S. STRASSBERG,*
STEVEN
ROSS,? and ELLEN
H. TODTS
of Utah, Salt Lake City, Utah tuniversity of Utah School of Medicine, Salt Lake City, Utah WA Medical Center, Salt Lake City, Utah *University
Abstract - Forty-two women, meeting criteria for bulimia, completed the MMPI. Cluster analysis of their scores revealed two distinct profile types. The first cluster, comprising about 64% of subjects, produced a mean profile in which only the Pd scale exceeded at score of 70. In contrast, about 36% of subjects yielded a cluster-derived mean profile that was significantly elevated on many scales, including Pd. D, Pt, and SC. The existence of these two very different subgroups of women with bulimia replicates previous work in this area and has potentially important implications for the description, treatment, and general understanding of those with this condition.
It has long been assumed that eating disorders, particularly bulimia and anorexia, are symptomatic of a variety of intrapsychic and interpersonal problems. Issues of anger, low self-esteem, dependency, inordinate needs for social approval and control, and other dynamics have all been hypothesized to be of importance in the etiology/ maintenance of these disorders (e.g., Johnson & Connors, 1987). The MMPI has been the most frequently used instrument in the empirical attempts to identify personality correlates of those (primarily women) with an eating disorder (e.g., Scott & Baroffio, 1986; Shisslak, Payda, & Crago, 1990). Most common in the literature on MMPI and eating disorders are profile elevations on the Pd (Psychopathic Deviation, scale 4) and D (Depression, scale 2) scales (e.g., Rybicki, Lepkowsky, & Arndt, 1989; Scott & Baroffio, 1986). There is substantially less agreement, however, regarding whether bulimics usually produce MMPI profiles suggestive of severe psychopathology (e.g., Biederman et al., 1986; Edwin. Andersen, & Rosell, 1988). One likely important reason for the heterogeneity in some of these findings concerns the use of average MMPI profiles to describe eatingdisordered individuals. Several researchers have noted that mean MMPI profiles may not always accurately characterize a clinical sample; that is, there may be few, if any, subjects whose profile actually matches that of the computed average profile (Prokop, 1988). In response to this problem, Rybicki, Lepkowsky, and Arndt (1989) cluster analyzed, rather than averaged, the MMPI scores of 38 bulimic female outpatients. Cluster analysis has the potential to yield subtypes of a clinical sample that may prove to be more characteristic of individual members of that group and, consequently, more clinically meaningful than averaging. Rybicki and co-workers’ analysis yielded two very different subtypes of bulimia. One cluster, comprising about 25% of subjects, was elevated, with seven clinical scales having a mean t-score value Requests for reprints should be sent to Donald S. Strassberg, Dept. of Psychology, SBS 502, University of Utah, Salt Lake City, UT 84112. 137
138
D. S. STRASSBERG et al.
greater than 75. This subtype most closely approximated the 8 (SC)-2 (D)-7 (Pt) threepoint code type. A second cluster, comprising about 75% of the bulimic patients, was much lower in overall profile elevation. Further, only one scale, 4 (Pd), exceeded a t score of 70 (i.e., t = 73). The dramatic differences, both qualitatively and quantitatively, in these profile types suggest substantial clinical value in cluster analysis when attempting to characterize bulimics via the MMPI. The present study was designed primarily to examine further the clinical value of a cluster-analytic approach in evaluating the MMPI performance of individuals with bulimia. Specifically, we attempted to replicate the findings of Rybicki, Lepkowsky, and Arndt (1989). METHOD
Subjects
and procedure
Subjects were recruited via an advertisement for volunteers placed in a university newspaper. A total of 48 females responded. All volunteers were interviewed independently by two PhD-level clinical psychologists, using a point-by-point inquiry based on the DSM-III criteria for eating disorders. Thirty-five of the women met the criteria for bulimia and for no other eating disorder. The mean age of this group was 23 years, mean weight as 120 pounds, and mean years of education was 14. A second group of seven women was identified who met not only the DSM-III criteria for bulimia but had a history of anorexia as well. This mixed group’s average age, weight, and education were 25.4 years, 106 pounds, and 12.5 years, respectively. The 42 women found to meet the criteria were then administered the full MMPI. RESULTS
The MMPI scores for all 42 subjects were subjected to a cluster analysis (SPSS/ PC+ 4.0, Quick Cluster; based on nearest centroid sorting with cluster centers assigned by the program) to identify profile subgroups in this population. Both twoand three-cluster solutions were found to represent the data well. Because of the similarity of the profiles yielded by the two- and three-cluster solutions, and because of our relatively small sample size, the decision was made to use the two-cluster solution (see Figs. 1 and 2). As can be seen from Figures 1 and 2, the two cluster-derived profiles were quite different, both in terms of their average elevation as well as their overall configuration. The mean Cluster 1 profile (Fig. 1), characterizing about 64% of subjects, had only one clinical scale, Pd, significantly elevated (t = 74). In contrast, the mean Cluster 2 profile (Fig. 2), characterizing approximately 36% of subjects, was extremely elevated, with four scales (D, Pd, Pt, SC) reaching at least t = 78, two of which (D and Pd) reached at least t = 85. Figures 1 and 2 also include the mean MMPI scores for the two clusters identified by Rybicki, Lepkowsky, and Arndt (1989) in their study of bulimic women. It can be seen that there is substantial correspondence for the findings of these two studies. Finally, subjects in the two clusters were compared regarding their scores on the MMPI Ego Strength (Es) scale. This was done because Rybicki, Lepkowsky, and Arndt (1989) reported that the bulimic women in their more elevated cluster had Ego Strength scores well below those in the less elevated cluster. As in their study, women from Cluster 2 in the present study scored substantially and significantly lower than those in Cluster 1 (Mean Es scores = 41.4 vs. 54.0, t = 4.71, p < .OOl).
Bulimia and MMPI
139
T-SCORE
,,i 80
60 CLUSTER RYBICKI __ L
F
K
1
CLUSTER 1 STRASSBERG
1234567890 MMPI
SCALE
MMPI Cluster 1 of bulimic subjects.
Fig. I.
DISCUSSION
Cluster analysis of the MMPI scores of the bulimic women who volunteered for this study revealed two very different profile types. Although the sample size in our study was not large, the fact that the two cluster-derived profile types revealed were
r
T-SCORE
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CLUSTER 2 STRASSBERG
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Fig. 2.
2
SCALE
MMPI Cluster 2 of bulimic subjects.
I
140
D. S. STRASSBERG et al.
so similar (in both nature and relative frequency) to those reported by Rybicki, Lepkowsky, and Arndt (1989) substantially increases the likelihood of these results being generalizable. The profiles generated from both studies (because of a common elevation on scale Pd) suggest poor judgment, low frustration tolerance, and difficulty with impulse control. However, those with the more elevated profile (Cluster 2 in the present study) would also be likely to be described as agitated, depressed, and prone to periodic acting out, often in self-defeating ways. Their self-concept would tend to be poor, and they would likely be seen as hostile and resentful, particularly toward family members. Such individuals distrust others, are hypersensitive to criticism, and often exhibit conflicts involving dependency and passivity. It is clear that these two cluster-derived profiles characterize women with very different personality characteristics and who, as patients, could require different approaches to treatment (Rybicki, Lepkowsky, & Arndt, 1989). Consistent with this was their different performance on the MMPI Ego Strength (Es) scale, with those in Cluster 2 having a much lower average Es score, suggestive of more severe and more chronic adjustment problems and a poorer prognosis for therapy. The present findings of at least two different subtypes of women with eating disorders are consistent with recent calls for a “thorough assessment of the [eatingdisordered patient] with an eye towards differential treatment options” (Rybicki, Lepkowsky, & Arndt, 1989, p. 258). Further, the present results, together with the findings of Rybicki, Lepkowsky, and Arndt (1989), strongly suggest that the MMPI (and its revision, the MMPI-2) offers at least one important tool for differentiating among bulimic women in a manner that has potential importance in describing, understanding, and treating those with this problem. REFERENCES Biederman, .I., Hebelow, W., Revinus, T., Harwatg, J., & Wise, J. (1986). MMPI profiles in anorexia nervosa patients with and without major depression. Psychiarry Revienp, 19, 147-154. Edwin, D., Andersen, A. E., & Resell, F. R. (1988). Outcome prediction by MMPI subtypes of anorexia nervosa. Psychosomatics, 29, 273-282. Johnson, C., & Connors, M. E. (1987). The etiology and treatment of bulimia nervosa. New York: Basic Books. Prokop, C. K. (1988). Chronic Pain. In R. L. Green (Ed.), The MMPI: Use M*ithspecij?c populations (pp. 22-49). Needham Heights, MA: Allyn & Bacon. Rybicki, D. J., Lepkowsky, C. M., & Arndt, S. (1989). An empirical assessment of bulimic patients using multiple measures. Addictive Behaviors, 14, 249-260. Scott, R. L., & Baroffio, J. R. (1986). An MMPI analysis of similarities and differences in three classifications of eating disorders: Anorexia nervosa, bulimia, and morbid obesity. Journal of Clinical Psychology, 42, 708-713. Shisslak, C. M., Payda, S. L., & Crago, M. (1990). Body weight and bulimia a discriminators of psychological characteristics among anorexic, bulimic, & obese women. Journal of Abnormal Psychology, 99. 380-384.
Pergamon
BRIEF REPORT MMPI PERFORMANCE AMONG WOMEN WITH BULIMIA: A CLUSTER-ANALYTIC STUDY DONALD
S. STRASSBERG,*
STEVEN
ROSS,? and ELLEN
H. TODTS
of Utah, Salt Lake City, Utah tuniversity of Utah School of Medicine, Salt Lake City, Utah WA Medical Center, Salt Lake City, Utah *University
Abstract - Forty-two women, meeting criteria for bulimia, completed the MMPI. Cluster analysis of their scores revealed two distinct profile types. The first cluster, comprising about 64% of subjects, produced a mean profile in which only the Pd scale exceeded at score of 70. In contrast, about 36% of subjects yielded a cluster-derived mean profile that was significantly elevated on many scales, including Pd. D, Pt, and SC. The existence of these two very different subgroups of women with bulimia replicates previous work in this area and has potentially important implications for the description, treatment, and general understanding of those with this condition.
It has long been assumed that eating disorders, particularly bulimia and anorexia, are symptomatic of a variety of intrapsychic and interpersonal problems. Issues of anger, low self-esteem, dependency, inordinate needs for social approval and control, and other dynamics have all been hypothesized to be of importance in the etiology/ maintenance of these disorders (e.g., Johnson & Connors, 1987). The MMPI has been the most frequently used instrument in the empirical attempts to identify personality correlates of those (primarily women) with an eating disorder (e.g., Scott & Baroffio, 1986; Shisslak, Payda, & Crago, 1990). Most common in the literature on MMPI and eating disorders are profile elevations on the Pd (Psychopathic Deviation, scale 4) and D (Depression, scale 2) scales (e.g., Rybicki, Lepkowsky, & Arndt, 1989; Scott & Baroffio, 1986). There is substantially less agreement, however, regarding whether bulimics usually produce MMPI profiles suggestive of severe psychopathology (e.g., Biederman et al., 1986; Edwin. Andersen, & Rosell, 1988). One likely important reason for the heterogeneity in some of these findings concerns the use of average MMPI profiles to describe eatingdisordered individuals. Several researchers have noted that mean MMPI profiles may not always accurately characterize a clinical sample; that is, there may be few, if any, subjects whose profile actually matches that of the computed average profile (Prokop, 1988). In response to this problem, Rybicki, Lepkowsky, and Arndt (1989) cluster analyzed, rather than averaged, the MMPI scores of 38 bulimic female outpatients. Cluster analysis has the potential to yield subtypes of a clinical sample that may prove to be more characteristic of individual members of that group and, consequently, more clinically meaningful than averaging. Rybicki and co-workers’ analysis yielded two very different subtypes of bulimia. One cluster, comprising about 25% of subjects, was elevated, with seven clinical scales having a mean t-score value Requests for reprints should be sent to Donald S. Strassberg, Dept. of Psychology, SBS 502, University of Utah, Salt Lake City, UT 84112. 137
138
D. S. STRASSBERG et al.
greater than 75. This subtype most closely approximated the 8 (SC)-2 (D)-7 (Pt) threepoint code type. A second cluster, comprising about 75% of the bulimic patients, was much lower in overall profile elevation. Further, only one scale, 4 (Pd), exceeded a t score of 70 (i.e., t = 73). The dramatic differences, both qualitatively and quantitatively, in these profile types suggest substantial clinical value in cluster analysis when attempting to characterize bulimics via the MMPI. The present study was designed primarily to examine further the clinical value of a cluster-analytic approach in evaluating the MMPI performance of individuals with bulimia. Specifically, we attempted to replicate the findings of Rybicki, Lepkowsky, and Arndt (1989). METHOD
Subjects
and procedure
Subjects were recruited via an advertisement for volunteers placed in a university newspaper. A total of 48 females responded. All volunteers were interviewed independently by two PhD-level clinical psychologists, using a point-by-point inquiry based on the DSM-III criteria for eating disorders. Thirty-five of the women met the criteria for bulimia and for no other eating disorder. The mean age of this group was 23 years, mean weight as 120 pounds, and mean years of education was 14. A second group of seven women was identified who met not only the DSM-III criteria for bulimia but had a history of anorexia as well. This mixed group’s average age, weight, and education were 25.4 years, 106 pounds, and 12.5 years, respectively. The 42 women found to meet the criteria were then administered the full MMPI. RESULTS
The MMPI scores for all 42 subjects were subjected to a cluster analysis (SPSS/ PC+ 4.0, Quick Cluster; based on nearest centroid sorting with cluster centers assigned by the program) to identify profile subgroups in this population. Both twoand three-cluster solutions were found to represent the data well. Because of the similarity of the profiles yielded by the two- and three-cluster solutions, and because of our relatively small sample size, the decision was made to use the two-cluster solution (see Figs. 1 and 2). As can be seen from Figures 1 and 2, the two cluster-derived profiles were quite different, both in terms of their average elevation as well as their overall configuration. The mean Cluster 1 profile (Fig. 1), characterizing about 64% of subjects, had only one clinical scale, Pd, significantly elevated (t = 74). In contrast, the mean Cluster 2 profile (Fig. 2), characterizing approximately 36% of subjects, was extremely elevated, with four scales (D, Pd, Pt, SC) reaching at least t = 78, two of which (D and Pd) reached at least t = 85. Figures 1 and 2 also include the mean MMPI scores for the two clusters identified by Rybicki, Lepkowsky, and Arndt (1989) in their study of bulimic women. It can be seen that there is substantial correspondence for the findings of these two studies. Finally, subjects in the two clusters were compared regarding their scores on the MMPI Ego Strength (Es) scale. This was done because Rybicki, Lepkowsky, and Arndt (1989) reported that the bulimic women in their more elevated cluster had Ego Strength scores well below those in the less elevated cluster. As in their study, women from Cluster 2 in the present study scored substantially and significantly lower than those in Cluster 1 (Mean Es scores = 41.4 vs. 54.0, t = 4.71, p < .OOl).
Bulimia and MMPI
139
T-SCORE
,,i 80
60 CLUSTER RYBICKI __ L
F
K
1
CLUSTER 1 STRASSBERG
1234567890 MMPI
SCALE
MMPI Cluster 1 of bulimic subjects.
Fig. I.
DISCUSSION
Cluster analysis of the MMPI scores of the bulimic women who volunteered for this study revealed two very different profile types. Although the sample size in our study was not large, the fact that the two cluster-derived profile types revealed were
r
T-SCORE
90 ,-“, ,_*’
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80
‘,
,,,’
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(/
-;
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60 : ; : , : ,t :
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CLUSTER RYBICKI
:
CLUSTER 2 STRASSBERG
: : : ;
40
‘;:
L
F
K
1
r
I
!
I
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/
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234567890 MMPI
Fig. 2.
2
SCALE
MMPI Cluster 2 of bulimic subjects.
I
140
D. S. STRASSBERG et al.
so similar (in both nature and relative frequency) to those reported by Rybicki, Lepkowsky, and Arndt (1989) substantially increases the likelihood of these results being generalizable. The profiles generated from both studies (because of a common elevation on scale Pd) suggest poor judgment, low frustration tolerance, and difficulty with impulse control. However, those with the more elevated profile (Cluster 2 in the present study) would also be likely to be described as agitated, depressed, and prone to periodic acting out, often in self-defeating ways. Their self-concept would tend to be poor, and they would likely be seen as hostile and resentful, particularly toward family members. Such individuals distrust others, are hypersensitive to criticism, and often exhibit conflicts involving dependency and passivity. It is clear that these two cluster-derived profiles characterize women with very different personality characteristics and who, as patients, could require different approaches to treatment (Rybicki, Lepkowsky, & Arndt, 1989). Consistent with this was their different performance on the MMPI Ego Strength (Es) scale, with those in Cluster 2 having a much lower average Es score, suggestive of more severe and more chronic adjustment problems and a poorer prognosis for therapy. The present findings of at least two different subtypes of women with eating disorders are consistent with recent calls for a “thorough assessment of the [eatingdisordered patient] with an eye towards differential treatment options” (Rybicki, Lepkowsky, & Arndt, 1989, p. 258). Further, the present results, together with the findings of Rybicki, Lepkowsky, and Arndt (1989), strongly suggest that the MMPI (and its revision, the MMPI-2) offers at least one important tool for differentiating among bulimic women in a manner that has potential importance in describing, understanding, and treating those with this problem. REFERENCES Biederman, .I., Hebelow, W., Revinus, T., Harwatg, J., & Wise, J. (1986). MMPI profiles in anorexia nervosa patients with and without major depression. Psychiarry Revienp, 19, 147-154. Edwin, D., Andersen, A. E., & Resell, F. R. (1988). Outcome prediction by MMPI subtypes of anorexia nervosa. Psychosomatics, 29, 273-282. Johnson, C., & Connors, M. E. (1987). The etiology and treatment of bulimia nervosa. New York: Basic Books. Prokop, C. K. (1988). Chronic Pain. In R. L. Green (Ed.), The MMPI: Use M*ithspecij?c populations (pp. 22-49). Needham Heights, MA: Allyn & Bacon. Rybicki, D. J., Lepkowsky, C. M., & Arndt, S. (1989). An empirical assessment of bulimic patients using multiple measures. Addictive Behaviors, 14, 249-260. Scott, R. L., & Baroffio, J. R. (1986). An MMPI analysis of similarities and differences in three classifications of eating disorders: Anorexia nervosa, bulimia, and morbid obesity. Journal of Clinical Psychology, 42, 708-713. Shisslak, C. M., Payda, S. L., & Crago, M. (1990). Body weight and bulimia a discriminators of psychological characteristics among anorexic, bulimic, & obese women. Journal of Abnormal Psychology, 99. 380-384.