Health Psychology Home Page
Papers written by students providing scientific reviews of topics related to health and well being
|Search||Home | Weight Loss | Alternative Therapy | Supplements | Eating Disorders | Fitness | Links | Self-Assessment | About this Page ||
Bulimia nervosa is a chronic psychiatric disorder that haunts the lives of many young women. The disorder is characterized by frequent episodes of binge eating followed by some sort of purging. The purging usually involves self-induced vomiting and can cause great damage to the body. Persons diagnosed with bulimia nervosa have a loss of control over these behaviors. Affecting the lives of 3-5% of young women, bulimia is a problem that is spinning out of control and nothing seems to be able to stop it. Binge eating disorder is another psychiatric disease that causes problems for many people. In this disorder, persons binge frequently but do not attempt to compensate for their eating by using purging techniques such as those used by persons suffering from bulimia nervosa.
There are many types of treatments that attempt to mitigate the symptoms of bulimia and binge eating disorder. But what causes the binges in binge eating disorder and what causes the binge-purge cycle in bulimics? How can the symptoms of these disorders be reduced or eliminated? If the causes of these behaviors are discovered, the behaviors can be reduced. There are several therapies that have proven to be fairly effective in treating persons diagnosed with bulimia nervosa. Drug therapy has made great advances in recent years and goes straight to the root of the problem. Drug therapy attempts to uncover the biological causes of the symptoms of bulimia nervosa and binge eating disorder.
A discovery made recently found that there is an inverse correlation among women with bulimia between the frequency of binge-eating and cerebrospinal fluid concentration of the major seratonin metabolite 5-hydroxyindoleacetic acid. Also, "Women with bulimia have been reported to exhibit blunted plasma cholecystokinin responses to eating a meal." These cholecystokinin satiety responses travel to the central nervous system via vagal afferents. Vagal afferent nerve endings have serotonin-3 and serotonin-4 receptors whose activation have been known to cause nausea and vomiting. Serotonin therefore "may affect vagal function at both central and peripheral sites of action"(Rissanen et. al. 1998). In several studies, the serotonin uptake inhibitor fluoxotine has reduced the binge eating symptoms of bulimia. Fluoxetine is also used in the treatment of depression but a higher dosage is needed for effective treatment of bulimia. Thus, we can conclude that fluoxetine works differently on patients who suffer from bulimia and on patients who suffer from depression.
One study done with fluoxetine tested its effects on vagal function in 41 volunteer healthy women and 25 women with bulimia nervosa. The study attempted to evaluate cardiac vagal tone in women with bulimia compared to healthy women at baseline. After an eight week treatment with fluoxetine or placebo, the vagal tone, along with the severity of symptoms was reevaluated within and between the groups.
A nurse therapist measured the severity of the symptoms (binge eating, purging) throughout the study, and a research psychiatrist evaluated them at 0 and 8 weeks using a semi-structured interview. The severity of the symptoms was also self-rated by the patients upon entry and completion of the study. Cardiac vagal tone was measured by the vagal tone monitor at 0 and 8 weeks.
Upon entry, "The patients with bulimia nervosa had a significantly elevated cardiac vagal tone and reduced heart rate compared with the healthy volunteers"(Rissanen et al 1998). After eight weeks however, fluoxetine normalized the high cardiac vagal tones but had no effect on heart rate. The placebo had no effect vagal tone or heart rate. Fluoxetine had no significant effects over placebo on bulimic symptoms in this study.
The fact that fluoxetine had no significant effects over placebo on the symptoms associated with bulimia in this study is interesting because other studies have shown greatly reduced symptoms with treatment of the drug. This is probably due to the small sample size used in this study. Using a larger sample size would most likely produce significant reductions in symptomatology. Furthermore, it must be assumed that fluoxetine in combination with some sort of behavioral therapy is much more effective than using fluoxetine alone.
Another study attempted to test the effects of fluoxetine on the symptoms of binge-eating disorder. This disorder has gained much attention in recent years due to increased recognition that the disorder is not only common but quite dangerous and a focus of much medical attention. There is no established treatment for the disorder but many doctors are putting their faith in serotonin selective reuptake inhibitors such as fluoxetine because of their effectiveness in treating bulimia nervosa.
This study to assess the efficacy of fluoxetine in binge-eating disorder took place over nine weeks and treated 85 outpatients diagnosed with the disorder. Patients were randomly assigned to therapy with fluoxetine or placebo. All doses were 50 mg capsules. Patients took one capsule each evening for a week and then the dose could be adjusted on an individual basis between 50mg and 300mg until the end of week nine. Patients were evaluated initially on frequency of binges, medical history, vital signs, blood tests, and urinalysis. Patients kept diaries to record binges and the number of capsules taken.(Hudson et al. 1998)
Patients were seen weekly during the study also and were assessed for number of binges experienced since the last visit, medication dosage, and vital signs. They were rated on the Clinical Global Improvement Scale (CGI). The mean dose after nine weeks for fluoxetine patients was 260mg. This mean was significantly higher than the placebo group who finished nine weeks of treatment. "The rate of reduction in the frequency of binges, the rate of decrease in the CGI severity scale, and the rate of increase in the CGI improvement scale were all significantly greater in the fluoxetine group the placebo group"(Hudson et al. 1998). Fluoxetine was also associated with a greater rate of reduction in body mass index than the placebo group. Weight loss after nine weeks was shown to be due to the reduction in frequency of binges.
It is important to be cautious in your interpretations of results from studies on drug treatments because many times when the response to the drug is high, the response to placebo is high as well. For example, in the above study, almost half of the subjects in the placebo group exhibited a greater that 50% reduction in binges per week. These results suggest that binge eating disorder may improve with drug or placebo. In some cases, patients only responded to placebo. The results of this study, therefore are not as clear cut as they may seem at first.
Another drug currently being tested for its efficacy in reducing the symptoms of bulimia nervosa is odansetron. This drug, like fluoxetine was developed from the belief that "the pathophysiological characteristics driving the abnormal behaviors involve an increase in the basal tone of the vagus nerve as a result of repeated and aggressive stimulation of the gastric branch of the vagus nerve by binge eating and vomiting"(Hartman et al. 1997). Odensetron is a 5-hydroxytryptamine type 3 receptor antagonist that decreases vagal transmission.
Five women who met the DSM-III-R criteria for bulimia nervosa were administered odansetron hydrochloride in this study. Treatment with odansetron consisted of three doses of 4mg daily as a base and then patients could take additional 4mg doses as needed up to 24mg per day. After one month, patients showed a significant decrease in symptoms. One patient had a total of only six sporadic binge-vomit cycles during months two through nine and had not required treatment with odansetron up to the time the study was written. Another patient elected to stop taking the drug after six weeks and relapsed immediately.(Hartman et al. 1997).
The patients in this study attribute the effectiveness of the drug to a decrease in the urge to engage in the binge-vomit behavior. Patients also reported a return of normal hunger and satiety. Treatment with odansetron is unique because a positive response to the drug is evident and reported by the patients during the first week. These results further support the claim that an increase in vagal tone drives the binge-vomit cycles in bulimics.
This study had a very small sample size thus it would be wrong to make any general conclusions from the results. The results do however correspond with many other studies done to determine the importance of the vagal tone drive.
Drug treatment has proven to suppress the symptoms of bulimia nervosa and binge eating disorder in several studies but cannot remove them. For example, only 20% of patients taking fluoxetine become symptom free on the maximum dose of 60mg. Other psychological treatments for bulimia and binge-eating disorder have been developed recently which reduce symptoms greatly. Psychotherapy and Cognitive Behavioral Therapy are the two which have had the most success. These treatments however, require specialized therapists and a lot of time and effort which excludes many people suffering from these disorders. One group of researchers attempted to increase the availability of the strategies used to reduce the negative symptoms by developing a "self-care manual containing cognitive behavioral education and treatment strategies"(Treasure et al. 1996).
The manual was evaluated in a study to see how effective it really was. Subjects were divided into two groups; one group was given the manual and they were told their progress would be evaluated after eight weeks. They were told that the book contained everything they needed to overcome bulimia. The other group was split in half with one half offered a standard sixteen week course of cognitive behavioral therapy. The other half was offered the same sixteen week course after eight weeks of waiting. Both groups exhibited significant reduction in total symptoms at the end of treatment. "The median score change for the sequential group was 4, decreasing from a median of 6 to a median of 2. The median score change for the CBT group was 4, again decreasing from a median of 6 to a median of 2"(Treasure et al. 1996).
The results show that a self care manual can be very effective even when the manual is used alone. When the manual alone is not sufficient, patients need fewer sessions of therapy to accomplish the same results in treatment. Using the manual alone is effective in reducing symptoms in 20% of people. The addition of eight CBT sessions after eight weeks of manual alone increases the effectiveness to 30% which is the same rate observed after sixteen sessions of CBT in this study. Treatment with both forms reduces the symptoms in 40%.
Researchers are still attempting to come up with effective ways of reducing the bingeing and purging symptoms of bulimia and binge eating disorder. Current research on the genetics of bulimia show very significant results with twin studies. Monozygotic twins have a 23% chance of developing the disorder if their twin is diagnosed with the disease. Results such as these show a promising future in our understanding of the disorder but studies such as the ones mentioned here must continue if we are to eliminate the symptoms. Further studies with the drug fluoxetine must be done to determine its long term effects because almost all patients suffering from bulimia or binge eating disorder require a longer treatment than the eight or nine weeks of the study. It is not known if the drug prevents relapses of symptoms in patients either.
Further studies must also be done with the drug ondansetron to determine its effects on the suppression of the binge-purge cycle. It must also be noted that drug therapies do not really change the way a person thinks about his or her body and donít succeed in changing peopleís habits. They simply create a chemical change in the brain that prevents certain behaviors. Cognitive therapies must be used in conjunction with drugs so that a person understands what they are doing and why it is harming them. For people who feel unable to overcome the barriers to seeking treatment, the self-help manual can be very effective. This manual should be researched and developed further because not only can people educate themselves, but therapists can have more time to focus on deeper problems and on patients who do not respond well to such therapies.
Hartman, Boyd K., Faris, Patricia L. Treatment of Bulimia Nervosa With Odansetron. Archives of General Psychiatry. 1997; 54: 969-970.
Hudson, James I., McElroy, Susan L. Fluvoxamine in the Treatment of Binge-Eating Disorder. The American Journal of Psychiatry. 1998; 155: 1756-1762.
Rissanen, Aila., Naukkarinen, Hannu. Fluoxetine Normalizes Increased Cardiac Vagal Tone in Bulimia Nervosa. Journal of Clinical Psychopharmacology. 1998; 18: 26-32.
Treasure, Janet., Schmidt, Ulrike. Sequential Treatment for Bulimia Nervosa Incorporating a Self-Care Manual. The British Journal of Psychiatry. 1996; 168: 94-98.
The Health Psychology Home Page is
produced and maintained by David Schlundt, PhD.
Vanderbilt Homepage | Introduction to Vanderbilt | Admissions | Colleges & Schools | Research Centers | News & Media Information | People at Vanderbilt | Libraries | Administrative Departments | Medical
|Return to the Health Psychology Home Page|
|Send E-mail comments or questions to Dr. Schlundt|