Evaluation of the cognitive functions in patients with chronic renal failure before and after renal transplantation.

Chronic renal failure (CRF) and dialysis treatment affect central nervous system and studies have shown that neurocognitive dysfunctions are caused by CRF and dialysis treatment. The aim of this study was to evaluate the changes in cognitive functions of CRF patients after renal transplantation. Neurocognitive functions of 40 renal transplantation patients aged 18-65 years were determined before, 6 and 12 months after transplantation between 2008 and 2010 using neuropsychological tests. Rey Auditory-Verbal Learning Test (RVLT), Rey Complex Figure Test (RCFT), ADAS-cog Test, Stroop Test (ST), Digit Span Test (DST), and Trail Making Test (TMT) were applied. The test results were statistically compared taking into consideration the patients' levels of education, age, gender, donor type, duration of dialysis, dialysis type, and duration of CRF. Neuropsychological test results statistically significantly increased in all the patients after renal transplantation (p < 0.05). The female patients' RVLT test results were statistically higher than the test results of the male patients (p < 0.05). DST, RCFT, RVLT, and (Verbal Fluency Test) VFT results were statistically higher in the patients who were 33 years old or younger (p < 0.05). The patients with high school and college education had statistically significantly higher results in all the tests when compared with the patients that were elementary school graduates (p < 0.05). DST forward task, ST, and RVLT results of the patients, who had received dialysis treatment for 1 year or less, were found to be statistically higher than the results of the patients who had received dialysis for more than 1 year (p < 0.05). The results of RCFT, RVLT, DST backward task, and VFT were statistically higher in the peritoneal dialysis patients than in the hemodialysis patients (p < 0.05). The donor type and the duration of CRF had no significant effects on the results (p > 0.05). The results of this study showed significant improvement in attention, memory, executive functions, pace of data processing and language functions in CRF patients after renal transplantation, as proven with neuropsychological tests.