Functional neuroimaging studies in functional dyspepsia patients: a systematic review

Abstract

This systematic review aims to provide an integrative understanding of the abnormal functional brain activity, visceral sensation, dyspeptic symptoms, and psychological changes of FD. Electronic and hand searches were conducted to identify functional neuroimaging studies involving FD patients. Sixteen studies were selected and divided into three categories: 10 resting state studies, three visceral distention studies, and three acupuncture studies. Changes were reported in several brain areas in FD patients including the frontal cortex, somatosensory cortex, insula, anterior cingulate cortex, thalamus, hippocampus, and amygdala. These brain activity changes were associated with visceral hypersensitivity, dyspeptic symptoms, poorer quality of life, anxiety, and depression. The results show that FD is associated with functional abnormalities in sensory and pain modulation, emotion, saliency, and homeostatic processing regions. The diversity of conditions, heterogeneous results, poorly standardized diagnoses of FD, and various comorbidities may be responsible for the variability in the results.

Functional dyspepsia

“…In patients with functional dyspepsia, altered neural activation in response to gastric distension or sham distension has been documented 149 , which supports altered processing not only during noxious visceral stimulation but also during anticipation. Compared with healthy individ uals, patients with functional dyspepsia also reveal alterations in the functional connectivity of brain regions at rest 149 and different structural brain measures, including regional grey matter volume and white matter microstructure [150][151][152][153] . Finally, emerging evidence supports alterations in central neuro transmitter systems, including the serotoninergic and endo cannabinoid systems, in functional dyspepsia [154][155][156] .…”

Inconsistent symptom clusters for functional gastrointestinal disorders in Asia: is Rome burning?

“…For example, in patients with FD, early satiety and fullness can be potentially caused by a failure of fundic accommodation50 or an alteration of visceral sensory function 51. Multiple factors ranging from altered central processing of afferents52 to alterations of vagal function53 or mucosal54 and systemic inflammation28 55 are probably linked to symptoms. This also could explain why ‘dirty’ drugs with multiple targets such as tricyclic antidepressants appear more efficacious in patients with IBS or FD while selective serotonin reuptake inhibitors are less impressive when compared with placebo 56 57.…”

Brain functional connectivity is associated with visceral sensitivity in women with Irritable Bowel Syndrome

“…The investigation of spontaneous, stimulus-independent brain activation and connectivity of intrinsic brain networks by resting-state fMRI (rsfMRI) extends knowledge derived from studies involving experimental pain models (Napadow and Harris, 2014). Existing rsfMRI studies in functional gastrointestinal disorders (FGIDs) support altered functional connectivity (FC), with most consistently reported alterations in the default mode network (DMN), salience and sensorimotor networks (Lee et al, 2016, Mayer et al, 2015a). …”