Assessment of cognitive functioning after living kidney donation: A cross-sectional pilot study

Chronic kidney disease (CKD) has emerged as a risk factor for cognitive impairment. Living kidney donation results in reduction of the donors' renal function. This is considered acceptable in general but possible associations with cognitive function have not yet been studied.

Sixty living kidney donors (LKD), who had donated between 2003 and 2012 at Hannover Medical School, underwent neurocognitive testing including attentional and memory testing. In a cross-sectional design results were compared with data of healthy controls (n = 40) and with norm data given in the respective test manuals adjusted for age, sex, and education.

The median age of the LKD was 58 (range 39-70) years and the median time since donation was 7 (range 4-14) years. The LKD did not differ from controls in most of the cognitive test results and a composite attention test sum score. However, LKD did worse than controls in tests of working memory, parallel processing of stimuli, and sustained attention. No differences were found regarding quality of life. In LKD cognitive test results correlated significantly only with educational level but not with time since transplantation, eGFR, somatic comorbidity, quality of life and levels of fatigue, distress, depression, and anxiety.

Our data show a fairly normal performance of LKD in most attentional and memory tests. However, our pilot study also suggests some cognitive impairment in attention tests in LKD which would need to be confirmed in longitudinal prospective studies.