Biochemical aspects of bulimia nervosa

The relationship between eating disorders and substance use: moving beyond co-prevalence research

The frequent comorbidity of eating disorders and substance use has been demonstrated consistently by research. Less is known about the basis of this relationship. A review of the literature indicates that the hypotheses proposed to clarify the etiological relationship between eating disorders and substance use have not been supported sufficiently or consistently by empirical evidence. General criticisms include: a lack of well developed models, a reliance on co-prevalence data, and a lack of integration of knowledge from eating disorder and substance use research. It is suggested that an understanding of the etiological relationship between eating disorders and substance use will be arrived at only after fundamental inquiries into the functional relationship between eating disorders symptomatology and substance use patterns have been conducted. A behavioral assessment approach is offered as a means of evaluating the functional relationship between eating disorder symptomatology and substance use.

Neuropharmacology of paradoxic weight gain with selective serotonin reuptake inhibitors

It has been suggested that weight gain associated with tricyclic antidepressants (TCA) reflect actions on dopamine (DA) and histamine receptors. However, a definitive cause is purely assumptive given the nonselective pharmacology of these agents. The selective serotonin reuptake inhibitors (SSRIs), as well as agents like dexfenfluramine (DFF), have emphasized the pivotal role of serotonin (5HT) in reducing carbohydrate (CHO) intake, and have provided a more selective tool with which to study appetite regulation. It would be expected that all SSRIs should exert a similar anorectic action. However, recent reports provide evidence to the contrary. Despite their claimed selectivity, SSRIs still interact, either directly or indirectly, with various critical neurotransmitter systems. In addition, although the anorectic action of fluoxetine (FLX) is well recognized, long-term follow-up studies in depressed patients and in obese nondepressed patients reveal that its weight-reducing effects are transient, even leading to a gain in body weight. Similarly, paroxetine (PRX) and citalopram (CTP) have also been associated with weight gain. These latter observations are unexpected because PRX and CTP are highly potent and selective SSRIs. A neuropharmacologic rationale for the apparent paradoxic effects of SSRIs on appetite not a review of neuronal regulation of appetite is presented in this article. As with the regulation of feeding, paradoxic weight gain observed with SSRIs appears to rest on the interaction of 5HT with multiple mechanisms, with the extent of weight gain observed being dependent on subtle, yet important pharmacologic differences within the group. Finally, the neurobiology of depressive illness itself, and of recovery from it, is a major contributing factor to individual response to these drugs.

Eating behavior of bulimics, self-identified binge eaters, and non-eating-disordered individuals: what differentiates these populations?

This article reviews and critiques the eating behavior literature comparing the binge and non-binge-eating episodes of three populations of normal-weight women: bulimics, self-identified binge eaters, and non-eating-disordered women. The specific behaviors evaluated are number of calories consumed during different types of eating episodes, frequency of binge eating, number of eating episodes, rate of food consumption, the macronutrient composition of the food ingested, and context and duration of eating. Differences in these populations' eating behavior are analyzed in terms of their theoretical contribution. It is concluded that differences in the observed behavior of these groups are consistent with restraint theory, purge opportunity, and the forbidden foods hypothesis. Conversely, results do not support carbohydrate craving theory or a deficit in the satiety mechanisms of bulimics. Suggestions for future research are presented.

Pharmacotherapy of the eating disorders: a commentary

During the last 10 yr, evidence has accumulated which indicates that the eating disorders of bulimia and anorexia nervosa (BN and AN) may be differentially affected by pharmacological treatment. Although the efficacy of drug treatment alone (relative to nonpharmacological approaches) has been debated, there is support for the generalization that all types of antidepressant medications have proven efficacious for bulimia but not for anorexia. These clinical observations are consistent with an extensive body of research concerning the regulation of ingestion, which indicates that the neurotransmitter serotonin plays an important role in mediating satiety. Such considerations have led to the "serotonin-hypothesis of bulimia," which postulates that BN represents an underlying "hyposerotonergic" condition and, conversely, that AN represents a "hyperserotonergic" state. Recently, however, two independent studies have shown that the antidepressant fluoxetine, which selectively blocks the synaptic re-uptake of serotonin, provided significant therapeutic benefit for anorexic patients. The implications of these apparently anomalous results for the "serotonin-hypothesis of BN" are discussed in an attempt to gain insight into the present pharmacotherapy of the eating disorders.

Advances in diagnosis and treatment of anorexia nervosa and bulimia nervosa

This paper reviews four areas of research into anorexia nervosa (AN) and bulimia nervosa (BN). First, in terms of diagnosis, the psychological concerns about weight and shape are now addressed in BN, bringing it more in line with the related disorder, anorexia nervosa. Second, studies of psychiatric comorbidity confirm the overlap between eating disorders and depression, obsessive compulsive disorder, substance abuse, and personality disorder. Nevertheless, there are reasons to accept the distinct qualities of each syndrome, and eating disorders are not merely a variant of these other conditions. Third, treatment advances in BN involve mainly cognitive-behavioural or interpersonal psychotherapies and pharmacotherapies primarily with antidepressants. The effect of combining more than one approach is beginning to be addressed. Finally, outcome studies involving people with both AN and BN have shown that the disorders "cross over" and that both conditions have a high rate of relapse. A renewed interest in the treatment of AN is needed.