Wide impairment of cerebral serotoninergic activity but inter-individual heterogeneity in bulimia nervosa patients: a pilot [(18)F]MPPF/PET study.

Objectives: Bulimia nervosa (BN) is associated with abnormalities of serotoninergic system. Functional or ligand specific brain imaging studies revealed abnormalities in non-overlapping regions. [(18)F]MPPF (4-(2-methoxyphenyl)-1-[2-(N-2-pyridinyl)-p-fluorobenzamido]-ethylpiperazine) is a selective 5-HT1A receptor antagonist with a serotonin-like affinity, capable to assess changes of brain serotoninergic activity in BN patients.

Methods: [(18)F]MPPF cerebral binding potential (BPND) was measured by positron emission tomography scan in nine purging-type BN patients and eleven age-matched controls. Voxel-based statistical parametric mapping (SPM) analyses were performed to assess BPND differences between the two groups and between each BN patient and controls group.

Results: Mean [(18)F]MPPF BPND was overall increased in BN patients. SPM analysis with revealed symmetrical large clusters of increased [(18)F]MPPF binding in insula, temporo-parietal cortex, prefrontal cortex, in limbic, paralimbic cortex and raphe nuclei. SPM individual analysis indicated significant heterogeneity of [(18)F]MPPF mapping within BN group, including cases with isolated up to widespread increased binding. [(18)F]MPPF BPND did not covariate with depression or eating behaviour-related scores.

Conclusions: Large clusters of increased [(18)F]MPPF binding in severe BN overlap previous results, separately described within fMRI or PET studies. The relationship between the inter-individual [(18)F]MPPF binding heterogeneity and serotoninergic modulators efficacy in these patients remains to be assessed.