Previous studies have shown that elderly patients experience higher trough levels of tacrolimus and are more sensitive to the effects of medications, they experience higher occurrence and severity of such medication related toxicities. Therefore, the investigators hypothesize that by transitioning patients from tacrolimus immediate release to Envarsus ®, the peak-dose effect will be eliminated or attenuated, leading to a significant decrease in neurocognitive toxicities in the older patient population.

The investigators will conduct a single-center, prospective, open-label, randomized study to evaluate the difference in neurocognitive side effects between Envarsus and immediate release tacrolimus. Eligible patients will be enrolled within 8 weeks post-transplantation. They will be administered a baseline panel of neurocognitive tests. They will then be randomized to either continue on immediate release tacrolimus or Envarsus. 6 weeks after randomization, the neurocognitive tests will be repeated.

Inclusion Criteria:

1. Recipient of a kidney transplant
2. Age 60 or greater at the time of transplant
3. Kidney graft is functional (not dialysis dependent) by 4 weeks post-transplant
4. Have IR tacrolimus as maintenance therapy
5. Have BMI < 35 at time of transplant
6. Achieve therapeutic tacrolimus level within 4 weeks post-transplant

Exclusion Criteria:

1. Recipient of a simultaneous non-kidney transplant (pancreas)
2. Had an episode of rejection before study enrollment
3. Had a TIA/CVA after transplantation and before study enrollment
4. Had a neurologic injury after transplantation and before study enrollment
5. Blindness
6. Have an mTOR inhibitor as maintenance therapy
7. Nonadherence, as determined by a trough level less than 7 ng/mL after achieving therapeutic level with no other rationale for sub-therapeutic levels.
8. Adults unable to consent
9. Pregnant women
10. Prisoners

While participants were enrolled in the study (6 week period for each individual).