Cognitive Impairment in Stage 5 CKD Is “Partly Reversible”

Patients with stage 5 chronic kidney disease (CKD) show significant improvement in several aspects of cognitive function after a single dialysis session, reports a study in Nephrology Dialysis Transplantation.

The researchers administered a battery of neuropsychologic assessments to 28 patients with stage 5 CKD in medically stable condition. The patients’ mean age was 55 years, and their mean time on dialysis was 46 months. The cognitive tests were performed twice within 24 hours: 1 hour before and 19 hours after the end of dialysis. To control for learning effects, one group was assessed after a first dialysis session and again before a second session. A group of age-matched individuals with normal kidney function was assessed as well.

The CKD patients scored significantly lower on tests of alertness, attention, working memory, logical and visual memory, word fluency, and executive function. Short-term memory, selective attention, and problem-solving and planning were similar for CKD patients versus control individuals.

Repeated testing after dialysis showed significant improvement in several cognitive measures, including logical and visual memory, memory quotient, psychomotor speed, executive function, and concentration. Other areas showed no difference from before to after dialysis; performance remained below the level shown by non-CKD control individuals.

Patients with stage 5 CKD have well-recognized impairment in cognitive function. There is ongoing debate as to whether some part of this impairment is reversible, particularly in response to hemodialysis.

The new study shows improvements in memory, executive function, and psychomotor ability from before to after a single dialysis session in maintenance hemodialysis patients. The results suggest a “reversible component” of decreased cognitive function in stage 5 CKD. “Treatment of cognitive deficits should start early in the beginning of a kidney disease to ensure the best psychological and nephrological care geared to specific patient needs,” the researchers conclude [Schneider SM, et al. Effect of a single dialysis session on cognitive function in CKD5D patients: a prospective clinical study. Nephrol Dial Transplant 2015; 30:1551–1559].