We have carried out the selection of adequate neuroprotective therapy in patients with postoperative cognitive dysfunctions on the basis of calculating the index of total cognitive deficit. The study was carried out in patients of different age groups: young, middle and elderly. The state of cognitive function in patients with acute surgical pathology was determined before surgery and on the 1st, 7th, 30th day after surgery. Total cognitive deficit was calculated. In each age group on the seventh day of the study, there were patients with a restored state of cognitive function at the preoperative level. Some patients had minor changes in cognitive function. In some patients, cognitive impairment was observed in comparison with the preoperative period. The results of cognitive function changes in different periods of the study and in different age groups made it possible to develop treatment regimens. Significant changes were noted in 28 % (mean age 68.9 years) on the 7th day. Treatment is recommended based on the diagnosis of the degree and structure of cognitive dysfunction according to the analysis of the results on the 7th day after the operation. Taking into account the obtained results, we have developed and proposed a formula for calculating the total cognitive deficit. Our findings on cognitive function in surgical patients after surgery under general anesthesia have allowed us to develop a formula for calculating the index of total cognitive deficit. This allowed us to formulate a tactic for further adjustment of the existing cognitive deficit using neuroprotective therapy.