What is the pathophysiology of functional dyspepsia related to anxiety?

Dyspepsia complexity. The heterogeneity of the patients and the complexity of gastric motor activity make it difficult to isolate one phenomenon given various emotional stressors and other central nervous system and neurohumoral factors. Genetic influences, medications, such as anti-inflamatory agents, and infectious agents all may contribute to the anxiety related dyspepsia.
Fear hormone. If you are under sufficient stress long enough you will secrete excessive acid. Make sure your internist is aware of this. Referral to a psychiatrist may be wise.
Visceral. hyperalgesia. This is due to a "crossed wire" in which the brain and gut do not communicate correctly. The brain tends to misinterpret normal feelings as being abnormal, like pain or nausea. Anxiety is an influence on the brain and modulates this crossed wire phenomenon. Medications like amitriptyline often help.