Bulimia nervosa is a severe psychiatric disorder characterized by recurrent binge eating episodes followed by inappropriate compensatory behavior to prevent weight gain such as self-induced vomiting. With this project, the investigators want to investigate the role of the neurotransmitter dopamine in bulimia nervosa. Dopamine is reported to have an important influence on the neural reward system and is involved in the processing of gains and losses. The reward system is functionally connected to the individual perception of rewards in the environment. A previous study revealed that under catecholamine depletion including dopamine depletion women suffering from bulimia nervosa in their past reported mild bulimic symptoms and their reward processing became dysfunctional: their ability to use rewarding stimuli for task solving was diminished. The aim of this study is to investigate the role of reduced dopamine availability in the development or maintaining of bulimia nervosa and in the dysfunctional processing of rewarding stimuli and negative visual information. Therefore, the investigators hypothesize that catecholamine depletion achieved by oral administration of alpha-methyl-paratyrosine (AMPT) will induce mild bulimic symptoms in females suffering from bulimia nervosa in their past. In addition, they will reveal dysfunctions in reward and emotional processing under catecholamine depletion. Using functional magnetic resonance imaging, the investigators propose that a reduced activation of the nucleus accumbens, a neural structure of the reward system, will be the neural correlate of this dysfunctional reward processing. Furthermore, the amygdala, a neural structure that is involved in emotional processing, will show a higher activation under catecholamine depletion. Genetic factors additionally have an influence on the dopaminergic system. Therefore, the investigators hypothesize that genetic factors, for example the COMT val-158-met polymorphism may have an effect on the behavioral and neural response to catecholamine depletion. In sum, this investigation may help to understand which changes in reward and emotional processing may lead to a reoccurrence of bulimic symptoms. In future, the findings of this study may help to develop individual pharmacological and psychotherapeutical interventions to enhance the outcome of treatment.
Name: AMPT/ Demser
Description: alpha-methyl-paratyrosine (AMPT, trade name: Demser) body-weight adjusted dosage (40 mg/kg body weight, maximum 4000mg) at 4 medication intake time points over 24 hoursType: DrugAMPT
Name: Diphenhydramine
Description: Diphenhydramine (25mg) at the first medication intake time pointType: DrugDiphenhydramine Diphenhydramine & Diphenhydramine & placebo
Name: Placebo
Description: Placebo at the second, third and fourth medication intake time pointType: DrugDiphenhydramine Diphenhydramine & Diphenhydramine & placebo
Allocation: Randomized
Crossover Assignment
There is one SNP
Therefore, the investigators hypothesize that genetic factors, for example the COMT val-158-met polymorphism may have an effect on the behavioral and neural response to catecholamine depletion. --- val-158-met ---
The COMT val-158-met polymorphism was found to play a critical role for the activity of the enzyme catechol-O-methyltransferase (COMT) that metabolizes catecholamines after they have been released into the synaptic cleft. --- val-158-met ---
In addition this study provided preliminary evidence that COMT val-158-met polymorphism explains some of the variance in the behavioral response to catecholamine depletion. --- val-158-met ---
An additional goal is to examine the effect of the COMT val-158-met polymorphism on neural activity. --- val-158-met ---
3. Participants with homozygous val-158 alleles of the COMT val-158-met polymorphism will show an increased activation in the ventral striatum during a reward task. --- val-158-met ---
4. Participants with at least one met-158 allele of the COMT val-158-met polymorphism will show higher amygdala activation during the encoding of negative emotional visual information. --- val-158-met ---