Exposure with response prevention treatment of anorexia nervosa-bulimic subtype and bulimia nervosa

Pergamon

0005-7967(95)00011-9

Behav. Res. Ther. Vol. 33, No. 6, pp. 685-689, 1995 Copyright © 1995 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0005-7967/95 $9.50 + 0.00

CASE HISTORIES AND SHORTER COMMUNICATIONS Exposure with response prevention treatment of anorexia nervosa-bulimic subtype and bulimia nervosa S I D N E Y H. K E N N E D Y , l R A N D Y K A T Z , 2 C H R I S T I N A S. N E I T Z E R T , I E L I Z A B E T H R A L E V S K I 1 and S A N D R A M E N D L O W l T Z 3 t The Clarke Institute of Psychiatry, Mood & Anxiety Division, 250 College Street, Toronto, Ontario, Canada M 5 T IR8, -'The Toronto Hospital, Toronto General Division, 200 Elizabeth Street, Toronto, Ontario, Canada and ~The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada MSG IX8. (Received 31 October 1994) Sunnnary--Binge exposure with response-prevention of bingeing (ERP-B) was evaluated in 20 female Ss within an inpatient eating disorders unit over 9 sessions as an adjunct to standard milieu therapy. Subjects met DSM-III-R criteria for either bulimia nervosa (BN) (n = 13) or the bulimic subtype of anorexia nervosa (AN-B) (n = 7). The average age of the Ss in each group was 26.5 ( + 8.8) and 24.1 ( _ 6.0)yr, respectively. Results indicate significant within-session and pre-post treatment effects in self-report measures 'urge to binge', 'lack of control', 'feelings of guilt' and 'tension'. Further analysis revealed that the AN-B subgroup had significantly greater reduction in 'depression' and 'urge to vomit' compared to the BN group. This study provides preliminary evidence that ERP-B deserves further investigation with long-term follow-up in both BN and AN-B patients and may be particularly advantageous in the AN-B subpopulation.

INTRODUCTION Since the original description of bulimia nervosa (BN) (Russell, 1979) and of bulimic (AN-B) and non-bulimic (AN-NB) subtypes of anorexia nervosa (Garfinkel, Moldofsky & Garner, 1980; Casper, Eckert, Goldberg & Davis, 1980), several treatment approaches for reducing binge eating and vomiting have been evaluated. These include pharmacological interventions, cognitive and interpersonal psychotherapies, and exposure with response prevention (ERP). In virtually all cases treatments have been evaluated in BN Ss while patients with the AN-B diagnosis have been excluded from these trials. ERP involves planned, sustained, and repetitive exposures in the context of response prevention (de Silva & Rachman, 1981). Two types of ERP have been systematically evaluated in the treatment of BN. Rosen and Leitenberg (1982) proposed an anxiety-reduction model of 'bulimia' in which vomiting served as the negative reinforcer of binge eating by removing the fear of weight gain. Thus, patients would be required to consume binge foods up to the point at which they would typically induce vomiting. They would then be supervised for up to 21 hr until the urge to vomit had dissipated (ERP-V) (Leitenberg, Rosen, Gross, Nudelman & Vara, 1988). Although this treatment was effective in a small number of cases, high attrition rates along with the impracticality of organizing binge conditions for each patient have limited the application of this form of ERP, which has been criticized for its emphasis on the centrality of vomiting as a maintaining factor in binge eating (Carter & Bulik, 1994). An alternative approach involves prevention of the actual binge (ERP-B). In this case, small amounts of binge foods are presented to the patient who may "touch it, smell it, lick it or eat a small amount" (Jansen, Broekmate & Heymans, 1992). Schmidt and Marks (1989) compared ERP-V and ERP-B among hospitalized bulimic patients and reported similar reductions in binge-vomit frequencies and other between-session measures. However, within-session comparisons showed greater reductions in urge to binge, anxiety, and liking of food in the ERP-B group. In this study we set out to examine the feasibility of performing ERP-B treatment in an inpatient unit, and to compare its effect on AN-B and BN patients. Standard treatment in this unit includes supervised meals and calorie adjustments for AN patients to promote a weekly weight gain of 1 kg (Kennedy & Shapiro, 1993). We hypothesized that the AN-B group, who have demonstrated a greater capacity for restrained eating than the BN group (Polivy & Herman, 1993), would respond better to the combination of nutritional and exposure treatment than the BN group who are more often characterized by disinhibition and affective instability (Steinberg, Tobin & Johnson, 1990).

METHOD Subjects Subjects were 20 drug-free female patients who were consecutively admitted to the inpatient unit of the Programme for Eating Disorders at the Toronto Hospital. They met criteria for inclusion in either the BN subgroup (n = 13) or the AN-B subgroup (n = 7) as assessed using the Structured Clinical Interview for the DSM-llI-R-Patient Edition (SCID-P) (Spitzer, Williams, Gibbon & First, 1990). They remained drug-free for the duration of the study. No significant differences were found between the groups for age, duration of illness or binge frequency. As expected, the BN subgroup had a significantly greater Body Mass Index (BMI) than the AN-B subgroup (t = 5.52, d f = 12,6, P < 0.0001) (see Table 1). 685

686

CASE HISTORIESAND SHORTERCOMMUNICATIONS Table I. Demographic data Age (yr) AN-B

BMI at admission

18 35 28 21 24 18 25 24.14 (+6.04) 19 20 30 23 22 20 50 31 19 26 33 20 32 26.54 (+8.80)

Means BN

Means

17.8 17.2 13.8 16.8 17.4 14.1 16.3 16.20 (+1.61) 19.5 19.9 22.1 21.3 22.8 19.3 22.7 20.0 23.4 22.2 22.9 22.5 29.3 22.15 (_+2.58)

Duration of illness (yr)

Binge frequency (times/week)

5 20 6 4 10 3 7 7.86 (_+5.81) I 4 14 3 1.5 2 5 1 8 9 8 2 6 4.96 (_+3.91)

14 35 7 15 2 2 28 14.75 (+12.90) 21 25 7 9 7 7 11 3 49 35 7 53 11 18.77 (_+16.91)

Procedure Subjects provided written informed consent following admission. Data were collected during 9 treatment sessions which were carried out at the same time 3 days per week (between 3-4 pm), for a total of 3 weeks. Each session lasted 45 min. During each session Ss completed a self-report 100 mm visual analog scale which assessed feelings of depression, tension, hunger, satiety, urge to binge, urge to vomit, urge to exercise, lack of control, guilt, food craving, feelings of fatness, and nourishment along a dimension from 0 (not at all) to 100 (extremely). These measures were completed at 10 min intervals and continued until anxiety had dissipated. Following assessment of baseline levels, patients were presented their own pre-selected assortment of favourite foods and were permitted to touch and taste these foods but were prevented from bingeing. For the first 3 sessions, staff remained present throughout the exposure. Patients were repeatedly encouraged to discuss their feelings, thoughts, and emotions regarding the binge exposure experience. During the second week, Ss were made aware of the observer's presence behind a two-way mirror. For the sessions conducted in the last week of treatment, staff observed from behind the two-way mirror, although the participants were told they may or may not be watched.

Statistical analysis Data were initially tested for normality and variables showing skewness were adjusted using logarithmic transformation. Repeated measures analysis of variance was used to determine significance among the 12 dependent variables from the visual analog scale. The design included one between-group factor, diagnosis, (BN, AN-B), and two within-group factors, time (first exposure, last exposure) and session (beginning, end). Session measures were assessed during each exposure. RESULTS

Treatment effects AN-B and BN subjects. From the possible 9 sessions, the mean number of sessions completed was 8, with a range of 6 to 9. There were no significant differences between groups for number of completed exposure sessions. Main effects occurred in 4 of the dependent variables. Table 2 shows the group means and levels of significance for these variables. A significant main effect of time was found for 'urge to binge' (F = 17.76, df= 1,18, P = 0.0005) with Ss reporting lower scores after the last exposure. A significant main effect was also found for session (F = 6.07, df= 1,18, P = 0.0241), indicating that patients reported a decreased urge to binge by the end of each exposure session. Similar results were revealed for 'lack of control'. A significant main effect was found for time (F = 11.13, df = 1,18, P = 0.0037), and session (F = 4.56, df= 1,18, P = 0.0467) indicating reductions in lack of control after the last exposure as well as at the end of each session. Main effects for time and session were also reported for 'guilt' ( F = 6 . 5 1 , df= 1,18, P =0.0020; F = 10.23, df= 1,18, P =0.0050, respectively). Scores were significantly reduced both at the end of each session and after the last exposure. Subjects also recorded significantly less 'tension' from the beginning to the end of the sessions (F = 5.45, df= 1,18, P = 0.0314), and from Table 2. Mean scores for anorexia nervosa-bulimic subtype and bulimia nervosa groups Variable Urge to binge Tension Lack of control Guilt

Group AN-B BN AN-B BN AN-B BN AN-B BN

First exposure Beginning End 53.06 52.97 75.11 76.49 54.29 65.53 83.69 76.06

43.26 39.57 65.31 57.14 46.94 55.60 76.31 68.14

Last exposure Beginning End 26.11 37.37 49.80 60.66 33.06 43.51 67.34 53.86

6.11 22.20 43.69 47.03 31.83 33.63 53.89 45.06

P value P.~m~= 0.0005 Pl~ssio.~= 0.0241 P.im~ = 0.0243 P~ion~ = 0.0314 P.im~l = 0.0037 Ptsessiom= 0.0467 P.~m~= 0.0050 P~*on~ = 0.0200

CASE HISTORIES AND SHORTER COMMUNICATIONS

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LAST EXPOSURE Fig. 1. Interaction effect for 'depression' in anorexia nervosa-bulimic subtype and bulimia nervosa patients (P = 0.0405). • AN-B; [] BN.

first to last exposure (F = 6.05, df= 1,18, P = 0.0243). No between-group effects as a result of diagnosis were found for these variables. Group differences. Analysis of depression scores revealed a main effect for time (F = 7.94, df = 1,18, P = 0.0114) and a significant two-way interaction of time x diagnosis (F = 4.88, df = 1,18, P = 0.0405). While self-reports of depression appeared to increase during the first week for the AN-B subgroup, during the last week scores substantially decreased. However, for the BN subgroup, depression remained relatively unchanged throughout the binge exposure treatment (see Fig. 1). A main effect of time was also found for the variable 'urge to vomit' (F = 18.52, df= 1,18, P =0.0004). As well, a significant two-way interaction for time x diagnosis was found (F = 5.41, df= 1,18, P = 0.0319), shown in Fig. 2. In the case of BN Ss, urge to vomit did not change throughout the exposure, while the AN-B subgroup reported an increase in urge to vomit during the first week followed by considerable reduction in scores by the end of the binge exposure treatment. The reported 'feelings of fatness' and 'urge to exercise' as well as 'nourishment', 'food craving', 'satiety', and 'hunger' remained unchanged throughout the exposure treatment. DISCUSSION The present study examined the feasibility of carrying out an exposure with response prevention of binge eating (ERP-B) trial on an inpatient unit for eating disorder patients and involved a comparison of this technique in BN and AN-B Ss. Both within session and over time (first to last exposure) effects were demonstrated for both groups on a number of important variables. Reduction in the ratings of urge to binge, tension, lack of control and guilt occurred within sessions and urge to binge, lack of control, urge to vomit, tension, depression and guilt ratings were all significantly decreased at the last exposure. However, no changes in the feeling of fatness occurred either within sessions or over time. Findings from this study add three contributions to the existing literature. So far as we are aware, this is the first study in which the subgroup of AN patients with bulimic symptoms (AN-B) have been systematically treated with ERP-B and

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LAST EXPOSURE Fig. 2. Interaction effect for 'urge to vomit' in anorexia nervosa-bulimic subtype and bulimia nervosa patients (P = 0.0319). • AN-B; [] BN.

compared to a group of BN Ss. Schmidt and Marks (1989) did include 3 Ss with a past history of AN, but did not report any subgroup interactions in their study. In our study interaction effects for urge to vomit and depression indicated a preferential response to ERP-B in the AN-B compared to the BN group. As a group, the AN-B patients are more rigid and follow a stricter dietary regimen than BN Ss (Polivy & Herman, 1993). This likelihood to adhere to rules might provide an explanation for their increased responsiveness to the ERP-B treatment programme. This study also examines the effect of adding an extra treatment to existing milieu therapy (see Kennedy & Shapiro, 1993). We previously assessed the effect of regular meal completion in the same inpatient unit among AN-B and AN-R Ss (Kennedy, Katz, Ford & Ralevski, 1994). The same self-report instrument was used to assess identical measures before and after lunch, during the first and sixth weeks of weight restoration treatment. Although some measures were improved, there was no significant change in 'urge to binge' and depression ratings before meals actually increased between the first and sixth weeks. This provides indirect support for the complimentary effect of exposure therapy in addition to the existing milieu treatment. A similar therapeutic approach has been successful in a German study involving BN inpatients (Tusehen & Bents, in press), in contrast to other reports in which the addition of a pharmacological intervention to existing milieu treatment failed to confer any extra benefit in the treatment of BN (Fichter, Leibl, Rief, Brunner, Schmidt-Auberger & Engel, 1991). Further evaluation of ERP-B in combination with other treatments may also be justified. Despite an earlier report that ERP-V in combination with cognitive-behaviour (CB) therapy conferred significant advantages over CB therapy alone (Wilson, Rossiter, Kleifeld & Lindholm, 1986), this has not been supported in subsequent comparative trials (Agras, Schneider, Arnow, Raeburn & Telch, 1989; Wilson, Eldridge, Smith & Niles 1991). This study provides an alternative to other treatment methods such as ERP-V, cognitive and interpersonal psychotherapies, and pharmacotherapy in the treatment of both BN and AN-B. However, the present study had a number of limitations which would need to be considered in future trials. Because these patients were inpatients in a carefully supervised inpatients eating disorder unit, measures of actual binge episodes were not practical. A subsequent trial of ERP-B alone or in combination should include measures of actual binge episodes as well as perceived urges and should include follow-up assessments for a minimum of 1 yr.

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REFERENCES

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