Neurocognitive Function Changes Following Kidney Transplant: A Prospective Study

Abstract

Rationale & objective: Patients with advanced kidney disease are at risk for cognitive impairment, which may persist after kidney transplantation. We sought to understand changes in neurocognitive function domains utilizing comprehensive cognitive assessments.

Study design: Prospective cohort study.

Setting & population: Single-center study of patients undergoing kidney transplantation.

Exposure: Kidney transplantation.

Outcomes: Changes in neurocognitive function as measured by the Repeatable Battery for Assessment of Neuropsychological Status (RBANS) and the Trail Making Test Parts A and B (TRAIL A and B) before transplantation (baseline) and compared to 3 months and 12 months posttransplant.

Analytical approach: Wilcoxon signed-rank and linear mixed effect models were utilized to assess changes in neurocognitive scores at 3 months and 12 months compared to baseline.

Results: Thirty-two patients were included with a mean age of 45 years, 47% female, 85% White, and 62% with at least some college education. Hypertension and diabetes were etiologies of kidney disease in 31% and 25% of patients, respectively. Baseline RBANS and TRAIL A and B scores averaged 84.7 ± 14, 40.4 ± 9.9, and 41 ± 11.5, respectively. Although there were posttransplant improvements in immediate and delayed memory at 3 months, these were not sustained at 12 months. There were no significant differences from baseline at 3 months and 12 months in RBANS index scores for language, visuospatial/constructional abilities, and attention. Compared to baseline, TRAIL A scores were not significantly different at 3 months but were significantly improved at 12 months, whereas TRAIL B scores improved significantly at both 3 months and 12 months.

Limitations: Single-center design and small sample size.

Conclusions: Utilizing comprehensive cognitive assessments, we found improvements in attention and executive function in the first posttransplant year as measured by TRAIL A and B. However, there was no significant change in global cognition as measured by RBANS. These findings identify cognitive domains for potential intervention in the posttransplant population.

Keywords: Kidney transplant; RBANS; TRAIL A; TRAIL B; neurocognitive function.

Figure 1

Patient enrollment and testing. DGF, delayed graft dunction; IS, immunosuppression; RBANS, Repeatable Battery for Assessment of Neuropsychological Status; Tac, tacrolimus; TRAIL A and B, Trail Making Test Parts A and B.

Figure 2

RBANS scores and paired tests. This figure shows longitudinal summary data for persons having RBANS scores at all 3 measurement points. The general population norm ± 1 SD, which pertains to all metrics, is indicated in green by the solid and dashed reference lines, respectively. The solid red line indicates the threshold below which scores are considered impaired. RBANS, Repeatable Battery for Assessment of Neuropsychological Status; SD, standard deviation.

Figure 3

TRAIL A and TRAIL B scores and paired tests. This figure shows longitudinal summary data for persons having TRAIL A and TRAIL B scores at all 3 measurement points. The general population norm ± 1 SD, which pertains to both metrics, is indicated in green by the solid and dashed reference lines, respectively. The solid red line indicates the threshold below which scores are considered impaired. SD, standard deviation; TRAIL A and B, Trail Making Test Parts A and B.