Helicobacter pylori infection and dyspepsia.

It has proved remarkably difficult to confirm or refute an association between Helicobacter pylori-induced gastritis and non-ulcer dyspepsia for several reasons. Dyspepsia has not been defined adequately and current definitions include a variety of symptoms that probably reflect a number of underlying pathophysiological processes. Dyspepsia is a symptom complex, rather than a specific disease entity, and cannot be easily identified. There are probably many causes of dyspepsia, and if H. pylori does cause symptoms, it may produce different symptoms in different people. However, little is known about variations in host susceptibility and H. pylori virulence, or their potential effect on symptomatology. In addition, the mechanisms responsible for dyspeptic symptoms are unknown, regardless of whether or not there is concomitant H. pylori-induced inflammation. A possible aetiological role for H. pylori in dyspepsia has been sought in three major types of study. Epidemiology studies have suggested that H. pylori is not a major cause of non-ulcer dyspepsia. However, both dyspepsia and H. pylori are common, and the studies cannot account for many of the variables detailed above. Pathophysiological studies have commonly reported a variety of motor and sensory 'abnormalities' in association with H. pylori, but none has been confirmed or reproduced. In eradication studies, there is continuing debate as to whether dyspeptic symptoms diminish with treatment. This is partly because of the high placebo-response rate and partly because many treatment regimens have not cured the infection. Suppression of bacterial growth may not affect symptoms significantly, if they are due to mucosal inflammation, and symptom resolution may take many weeks or months following cure of H. pylori and the associated gastritis. Recent findings have shown that symptom reduction is more evident 1 year after eradication of H. pylori than after 4 weeks. There is a continuing and urgent need for well-designed studies to assess the long-term effect of H. pylori and its cure on both gastrointestinal function and dyspeptic symptoms.