Study: Kidney disease-related cognitive impairment may improve after transplantation
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Key takeaways:
- Logical memory improved after kidney transplantation to a similar status as normative values.
- Digit symbol substitution and category fluency scores also improved.
Kidney disease-related cognitive impairment, such as episodic and verbal declarative memory, may improve after transplantation, researchers found in a longitudinal study.
“Cognitive impairment is common in patients with kidney failure and affects kidney transplant (KT) eligibility, quality of life and survival,” Aditi Gupta, MD, MS, of the departments of internal medicine and neurology at the University of Kansas Medical Center, wrote with colleagues. While function may “improve with KT, the extent of improvement and differential effect of KT on specific domains of cognition remain unclear.”
To that end, researchers of the single-center, prospective cohort trial examined adults who were placed on a waitlist for a kidney transplant at an academic center and were expected to receive a transplant within a year. The aim was to assess the effect of transplantation on varying cognitive domains.
Investigators measured cognitive function with standard neuropsychological tests in 101 patients pre-transplant, in 78 patients 3 months post-transplant and in 83 patients 1-year post-transplant. The study adjusted for age, sex, race, education and assessment count.
Change in global cognitive function pre- to post-transplant was the primary outcome.
Patient scores in two logical memory tests that evaluated episodic/declarative memory were lower pre-transplant compared with normative values from National Alzheimer Coordinating Center data, according to the findings. The same was true of results from a digit symbol substitution test for psychomotor speed/visuospatial function, a mini mental state exam, category fluency (animal naming) and digit span backward test.
Logical memory improved after transplantation to a similar status as normative values, the researchers found. Digit symbol substitution test and a category fluency test for semantic memory/verbal fluency/language improved as well, but digit symbol substitution test scores remained lower than normative values. Scores in a trail-making test for working memory/attention and executive function did not change, Gupta and colleagues noted. Mini mental state exam and digit span tests were also the same.
“The differential improvement in different cognitive domains after KT may reflect difference in underlying mechanisms affecting specific cognitive domains; with some being reversible (eg, metabolic changes), while others being irreversible (eg, cerebrovascular disease or leukoaraiosis),” they wrote. ... “This knowledge of differential improvement in cognitive domains after a KT is relevant for clinical decision-making.”
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