Neurocognitive Function Changes With Extended-Release Tacrolimus Among Older Kidney Transplant Recipients

Neurocognitive functions will be assessed across multiple cognitive domains using the NIH toolbox-Cognitive battery (NIHTB-CB) version 3. The NIHTB-CB version 3 encompasses seven tests to assess attention, executive function, language, memory, and processing speed. The total cognition composite will be derived by averaging normalized scores. The results will be reported in Standard Scores [SS; mean of 100, standard deviation (SD) of 15] adjusting the age of the subject. The investigators will compare the changes in standard score from baseline between the two intervention groups.

The fluid composite score will be obtained using the NIH toolbox-Cognitive battery (NIHTB-CB) version 3, similarly as described above. The fluid cognition composite will be derived by averaging normalized scores. The results will be reported in Standard Scores [SS; mean of 100, standard deviation (SD) of 15] adjusting the age of the subject. The investigators will compare the changes in standard score from baseline between the two intervention groups.

The crystallized composite score will be obtained using the NIH toolbox-Cognitive battery (NIHTB-CB) version 3, similarly as described above. The crystallized cognition composite will be derived by averaging normalized scores. The results will be reported in Standard Scores [SS; mean of 100, standard deviation (SD) of 15] adjusting the age of the subject. The investigators will compare the changes in standard score from baseline between the two intervention groups.

The total composite score will be obtained using the NIH toolbox-Cognitive battery (NIHTB-CB) version 3, similarly as described above. The total cognition composite will be derived by averaging normalized scores. The results will be reported in T scores (mean of 50 and SD of 10) with adjustments for age, gender, education, and race/ethnicity. The investigators will compare the changes in T score from baseline between the two intervention groups.

The fluid composite score will be obtained using the NIH toolbox-Cognitive battery (NIHTB-CB) version 3, similarly as described above. The fluid cognition composite will be derived by averaging normalized scores. The results will be reported in T scores (mean of 50 and SD of 10) with adjustments for age, gender, education, and race/ethnicity. The investigators will compare the changes in T score from baseline between the two intervention groups.

The crystallized composite score will be obtained using the NIH toolbox-Cognitive battery (NIHTB-CB) version 3, similarly as described above. The crystallized cognition composite will be derived by averaging normalized scores. The results will be reported in T scores (mean of 50 and SD of 10) with adjustments for age, gender, education, and race/ethnicity. The investigators will compare the changes in T score from baseline between the two intervention groups.

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The Standardized Outcome in Nephrology-Life Participation (SONG-LP) questionnaire will evaluate each participant's engagement in significant life domains in correlation with the intervention. This questionnaire assesses life participation in the areas of leisure, family, work, and social activities through four simple questions. The score ranges from 4 to 20, with a higher score indicating greater engagement in life activities. The difference in changes of total score from baseline between the two intervention groups will be obtained.

Quality of Life in Essential Tremor (QUEST) questionnaire will be used to assess tremors subjectively. This questionnaire comprises 30 items contributing to the five dimensions: physical/activities of daily living, psychosocial, communication, hobbies/leisure, and work/finances. The investigators will also obtain self-rated tremor severity in various body parts. The score ranges from 0 to 120, with a higher score indicating a greater impact on their QOL from tremor. The investigators will compare the changes in total score and the score on each scale from baseline between the two intervention groups.

The investigators will assess each participant's sleep quantity using wearable devices. The participants will be instructed to wear the device continuously for 14 days at pre-specified time points during the study period. Sleep quantity will be represented by the total amount of time spent asleep. The difference in changes in sleep quantity from baseline will be compared between the two intervention groups.

The investigators will objectively assess each participant's sleep quality using wearable devices. The participants will be instructed to wear the device continuously for 14 days at pre-specified time points during the study period. Sleep quality will be measured as a percentage of time spent in deep sleep and REM sleep to the total sleep time. A higher percentage indicates a better sleep quality. The changes in sleep quality from baseline will be compared between the two intervention groups.

The investigators will analyze the differential impact of the intervention in participants aged 75 years and older, compared to those under 75 years old.

The investigators will perform a subgroup analysis for each outcome based on gender to determine whether the treatment effect varies between males and females.

The investigators will analyze the differential impact of the intervention in participants with Bachelor's degree holders, compared to those without Bachelor's degree holders.

The investigators will perform a subgroup analysis for each outcome based on baseline cognitive function to determine whether the treatment effect varies according to baseline cognitive function. Participants with a baseline NIHTB-CB total composite T score ≤ 43 (corresponding to the lower 25th percentile adjusted for age, gender, education, and race/ethnicity) will be separately analyzed to those with a score > 43.