Kidney Transplantation Improves Cognitive and Psychomotor Functions in Adult Hemodialysis Patients

Background: Kidney failure is believed to have a negative impact on cognitive function, and cognitive impairment is common among maintenance hemodialysis (HD) patients. Previous studies have shown a beneficial effect of kidney transplantation in certain cognitive tests but not across all cognitive domains assessed. But, most of these studies performed a cross-sectional analysis, suffered from lack of standardization of adequate dialysis dose, hemoglobin level, and insufficient sensitivity of neuropsychological tests. The aim of this study was to evaluate the effect of successful kidney transplantation on cognitive and psychomotor function in adequately dialyzed HD patients without severe anemia, using sensitive neuropsychological tests. Methods: Twenty-one medically stable patients (aged 45.1 ± 7.9 years) on maintenance HD (7.6 ± 4.2 years) were investigated before and 20.5 ± 8.5 months after successful kidney transplantation using Complex Reactiometer Drenovac, a battery of computer-generated psychological tests which measure a simple visual discrimination of signal location, short-term memory, simple convergent visual orientation and convergent thinking. Results: Our findings indicated significantly better cognitive and psychomotor performance after transplantation on tests that assess processing speed, attention, short time memory, convergent thinking and executive functioning. Also, significant negative correlation between follow-up time after transplantation and cognitive and psychomotor performance in minimum time of solving test of convergent thinking was found. Conclusion: We conclude that cognitive and psychomotor functions are superior after successful kidney transplantation compared with HD, and that early beneficial effects of transplantation are not transient and cognitive and psychomotor performance might be even improved in time following successful transplantation.