Improvement in specific aspects of neurocognitive performance in children after renal transplantation

Abstract

Background: Chronic renal failure in childhood is considered to affect neurocognitive function adversely, and kidney transplantation may ameliorate the deficits. However, previous studies have suffered from the use of poorly matched control groups, comparison of transplant with uncorrected uremia, lack of standardization of dialysis, and insufficiently sensitive neuropsychological tests.

Methods: We studied nine medically stable children and adolescents age 14.2 +/- 3.5 years with end-stage renal disease prior to and again one year after successful renal transplant. At baseline, the Wechsler Intelligence Scale for Children-III (WISC-III) or the Wechsler Adult Intelligence Scale-Revised (WAIS-R) was performed. Repeatable tests used before and after transplant included the Paced Auditory Serial Addition Test (PASAT) or the Children's Paced Auditory Serial Addition Test (CHIPASAT), the Stroop Color-Word Naming Test, the Buschke Selective Reminding Test, the Meier Visual Discrimination Test, the Grooved Pegboard Test, the WISC-III or the WAIS-R Coding subtests and the Trailmaking Test. Computer-based measures of mental processing speed, reaction time, and discrimination sensitivity included the Cognitive Abilities Test (CAT) and the Connors Continuous Performance Test (CPT). Formal kinetic modeling of dialysis delivery ensured adequate renal replacement therapy. Transplant function was good on stable doses of immunosuppressives, without recent rejections at the time of testing.

Results: Within-subject comparison showed statistically significant improvement in mental processing speed by CAT, reaction time and discrimination sensitivity by CPT, and working memory by PASAT/CHIPASAT after renal transplant. Other measures were unchanged.

Conclusion: Mental processing speed and sustained attention improved in children after renal transplantation in a carefully controlled prospective cross-over study.