The purpose of this study is to determine if cognitive function improves in patients converted from tacrolimus immediate release (TAC IR) to Envarsus XR® (tacrolimus extended release) using an objective measure of cognition.

To assess cognitive function while on TAC IR and then three months after conversion to TAC XR using a traditional cognitive assessment, Montreal Cognitive Assessment (MoCA), and a broader cognitive assessment. This assessment will be used to determine if there is an objective improvement in cognitive function after conversion from TAC IR to TAC XR in kidney transplant recipients.

Inclusion Criteria:

• Post-renal transplant on stable TAC IR for at least 6 months who are converting to TAC XR regardless of indication.
• Patients receiving their post-transplant care through the Yale-New Haven Transplantation Center (YNHTC) regardless of where they were originally transplanted.

Exclusion Criteria:

• History of dementia or stroke
• Reside in a nursing home
• Newly started on an opiate, amphetamine, or benzodiazepine
• Non-English speaking (due to lack of NIH toolbox assessments in other languages)
• Patients that exhibit signs of acute infection, hemodynamic compromise or other signs of critical illness (e.g. respiratory distress requiring mechanical ventilation)
• Recipients of a multiorgan transplant
• Pregnant women
• Transplant recipients unable to provide informed consent to participate in this research