Getting a new kidney can boost brain function

By Megan Rauscher

NEW YORK (Reuters Health) - People with kidney disease often suffer from cognitive impairment, but kidney transplantation can improve their mental performance, research presented Thursday at the Society of Nephrology's annual meeting in Philadelphia confirms.

It's well known that chronic or advanced kidney disease requiring dialysis is associated with declining cognitive function. Previous small studies have suggested that cognitive impairment in dialysis patients is reversed by successful kidney transplantation.

To investigate further, Dr. Mark Unruh of the University of Pittsburgh in Pennsylvania and colleagues assessed cognitive performance before and after kidney transplantation in 37 patients with advanced kidney disease. They also assessed cognitive function at two different time points in a matched control group of 23 advanced kidney disease patients who did not receive a kidney transplant.

Unruh and colleagues found a statistically significant improvement in performance on tests of verbal learning and memory, attention, and language after patients received kidney transplants.

They found no such improvement in patients who did not have a kidney transplant. In fact, cognitive test scores declined in these patients over time.

"While those treated with kidney transplant demonstrated small but significant improvements in specific domains of cognitive performance, a comparison group of patients that did not receive a kidney transplant showed decrements in cognitive performance," Unruh commented.

"These findings confirm previous work with smaller numbers of patients and provides longitudinal validation of findings of studies examining only a cross-section of kidney transplant recipients," he added.

Furthermore, Unruh said these findings support the position that kidney transplant provides optimal replacement of kidney function and "provides an opportunity to improve quality of life and rehabilitation in patients with advanced chronic kidney disease."