Research methods in abnormal psychology

Experimental Methodologies: Bulimia Nervosa

Annotated Bibliography in Abnormal Psychology

Bara-Carril, Nuria, Williams, Christopher J., Pombo-Carril, Maria G., Reid, Yael, Murray, Kathryn, Aubin, Susan et al. (2004). A preliminary investigation into the feasibility and efficacy of a CD-ROM-based cognitive-behavioral self-help intervention for bulimia nervosa. International Journal of Eating Disorders, 35(4), 538-548.

A quasi-experimental study was carried out to test the efficacy of a CD-ROM-based CBT self-help intervention for bulimia. Subjects with a diagnosis of bulimia (N = 36) or eating disorder not otherwise specified (EDNOS; N = 9) were recruited as they presented at an eating disorders clinic in South London. The EDNOS patients met all the criteria for bulimia except for the frequency of binge eating and purging behavior. The exclusion criteria included an inability to understand English, anorexia nervosa, psychosis, acutely suicidal, current substance abuse, severe learning disability, and an inability to attend sessions. Treatment consisted of eight sessions interacting with the CBT material on the CD-ROM. Motivational and educational strategies were also incorporated into the material. The outcome measure was the Short Evaluation of Eating Disorders Symptoms.

Of the 39 subjects for which outcome data was available, a significant reduction in binging and purging occurred with treatment. The decrease in over-exercise was not statistically significant, but the sample size very small. Decreases were also noted for laxative/diuretic use and food restriction. The main limitations of the study were small sample size and the use of antidepressant medications by many of the test subjects. The authors also discussed their concern that a CD-ROM treatment modality may not be widely accepted by patients, especially those who prefer to interact with a therapist. The dropout and compliance rate was also high, with only 19 subjects completing all eight sessions.

Hay, Phillipa P.J., Bacaltchuk, Josue, Stefano, Sergio, and Kashyap, Priyanka. (2009). Psychological treatments for bulimia nervosa and binging. Cochrane Database of Systematic Reviews, Issue 4, Article No. CD000562.

Hay and colleagues sought to determine the relative efficacy of a number of different psychological approaches to treating the eating disorders, bulimia nervosa and binge eating, by using a meta-analysis approach. The meta-analysis included 3,054 study participants from 48 separate studies. The inclusion criteria were adults above the age of 16, males and females, patients, and healthy controls. The diagnoses included purging and non-purging bulimia, binge eating disorder, and EDNOS. The treatments modalities included in this study were cognitive-behavioral therapy (CBT), cognitive-behavioral therapy for bulimia nervosa (CBT-BN), nutritional counseling, interpersonal therapy, hypnotherapy, psychoanalytic/psychodynamic, self-help, and several others.

The primary result from the meta-analysis is that CBT generally, and CBT-BN specifically, was shown to be an effective treatment for bulimia and related eating disorders. Interpersonal psychotherapy and other forms of psychotherapy were found to be effective, but these treatment modalities took longer to achieve statistically significant remission rates. However, psychotherapy alone was found to be insufficient to achieve significant results. The authors concluded that larger and better-controlled studies are needed to discriminate between the relative efficacy of each treatment approach. In addition, despite the large collective patient population examined in the meta-analysis, effect sizes were still apparent when examining distinct patient groups.

Homan, Philipp, Grob, Simona, Milos, Gabriella, Schnyder, Ulrich, and Hasler. (2013). Reduction in total plasma ghrelin levels following catecholamine depletion: Relation to bulimic and depressive symptoms. Psychoneuroendocrinology, published online 16 Jan. 2013 ahead of print, 1-8.

To better understand the relationship between mood, plasma ghrelin levels, and eating disorders, Homan and colleagues conducted a randomized, double-blinded, controlled trial (RCT) to test the effects of catecholamine depletion using alpha-methyl-paratyrosine (AMPT). The experimental subjects enrolled in the study were 23 females between the ages of 19 and 39, with a clinical diagnosis of bulimia nervosa under remission for the past 6 months. Exclusion criteria included lifetime psychosis, Axis I psychiatric disorder, major medical problems, psychoactive medication within the last 6 months, pregnancy, lifetime substance abuse, current suicide ideation, or a history of suicide attempts. The exclusion criteria for the 29 control subjects were no psychiatric disorders, including first degree relatives.

Compared to controls, the remitted bulimics were significantly more depressed, had lower body mass indexes, and scored higher on bulimia symptoms. AMPT treatment significantly lowered ghrelin levels and induced depressive symptoms in both the experimental group and controls, but the remitted bulimics were more likely to become depressed. However, no association was found between ghrelin levels and severity of bulimia symptoms. The limitations mentioned by the authors included an inability to determine the direction of causality between depression and ghrelin, if there is one, and the inclusion of women regardless of where they are in the menstrual cycle. The small size of the study could have also precluded finding a significant effect between ghrelin levels and bulimia symptoms.

Schapman-Williams, Ann M. And Lock, James. (2007). Using cognitive-behavioral therapy to treat adolescent-onset bulimia nervosa: A case study. Clinical Case Studies, 6(6), 508-524.