Background: Varying results on the cognitive outcome of children who have undergone kidney transplantation (KTx) have raised concern for specific neurocognitive difficulties.
Methods: Fifty children with KTx were assessed at a mean age of 11.1 (SD 3.2; range 6.3-16.4), on average 6.9 (SD 3.6; range 1.0-14.1) years post-operatively. A standardized test of intelligence [Wechsler Intelligence Scale for Children (WISC-III)] and neuropsychological tests from NEPSY-II were administered. The neuropsychological profile of KTx children was compared to that of a control group matched for gender, age and maternal education.
Results: The KTx children had a lower intelligence quotient (83.9) than the test norms (100.0, P < 0.001). On neuropsychological assessment, the KTx group scored generally lower than the control group did (P < 0.001). The difference was evident in both the verbal and visuospatial domains, on a sub-test of complex auditory attention, verbal working memory and facial affect recognition. When children with neurological co-morbidity were excluded, the remaining group still scored lower than the controls did on Comprehension of Instructions (P = 0.06), Design Copying (P = 0.007) and Affect Recognition (P = 0.018). A better cognitive outcome was mainly associated with the absence of neurological co-morbidity, younger age, shorter disease duration and sustained kidney function. Children with congenital nephrosis had a similar outcome to those with other diagnoses.
Conclusions: KTx children exhibit a pattern of effects in their cognitive outcome in which both the visuospatial and language domains are affected, but visual memory and simple auditory attention remain intact. Patients without neurological co-morbidity exhibit impairment in receptive language, visuospatial functions and in recognizing emotional states.