Effect of Gastrectomy on Gut Microbiome and Cognitive Function

Perioperative neurocognitive disorders is a common postoperative complication in elderly surgical patients. The role of gut microbiota in cognitive function has been concerned in recent years. Studies suggests that gastrointestinal surgery may affect the gut microbiota, and the effect varies between surgical procedures. In this study, the investigators will compare the differences of gut microbiota between total gastrectomy and double-tract reconstruction, to investigate the effect of gastric acid on the gut microbiota colonizing, and the effect of different surgical procedures on the postoperative cognitive function of proximal gastric cancer patients.

Perioperative neurocognitive disorders is a common postoperative complication in elderly surgical patients, especially in gastrointestinal tumors and cardiac on-pump surgery, and the mechanism is not clear yet. The role of gut microbiota in cognitive function has been concerned in recent years, and the applicant's previous study also found significant differences in the composition of gut microbiota and metabolites in elderly orthopedic surgical patients with postoperative cognitive dysfunction compared with the control group, and that the differential metabolites were mainly enriched in the metabolic pathway of protein digestion and absorption. Studies suggests that gastrointestinal surgery may affect the gut microbiota, and the effect varies between surgical procedures. The incidence of proximal gastric cancer is increasing. In order to prevent severe gastroesophageal reflux, total gastrectomy is mostly performed. However, after total gastrectomy, food directly enters into the intestine, followed by insufficient mixing of gastric acid and food. Patients are prone to nutrient absorption disorders, which may cause changes in gut microbiota. The double-tract reconstruction allows food to enter the distal gastrointestinal tract via two pathways, successfully solving the problems of gastroesophageal reflux, gastroparesis, and long-term nutritional disorders in patients after proximal gastrectomy. In this study, the investigators aim to investigate the effect of gastric acid on the gut microbiota colonizing, and the effect of different surgical procedures on the postoperative cognitive function of proximal gastric cancer patients. The investigators will compare the differences of gut microbiota between total gastrectomy and double-tract reconstruction by 16S ribosomal ribonucleic acid (rRNA) gene sequencing and metabonomics technology, and evaluate the postoperative cognitive function by Mini-mental State Examination scales and Montreal Cognitive Assessment scales.

Eligibility Criteria:
Inclusion Criteria:

1. Clinical diagnosis of proximal gastric cancer and will be performed gastrectomy
2. American Society of Anesthesiologists (ASA) classification I-III
3. Aged 40-80 years
4. Perioperative consciousness

Exclusion Criteria:

1. Central nervous system and psychological disorders
2. Chronic use of sedatives, antidepressants within the last year
3. Parkinson's disease
4. Severe immunosuppression
5. Severe hearing or vision impairment
6. Drug dependence; alcoholism
7. Inability to communicate with a physician