Cognitive impairment in kidney transplanted patients

Abstract

Chronic kidney disease affects almost all of the organs. Recently, more attention has been paid to the kidney and the central nervous system connections. In patients on kidney replacement therapy, including kidney transplantation, there is an increased prevalence of cognitive impairment, and depression and other neurological complications, such as cerebrovascular disorders and movement disorders. Kidney transplant recipients need an assessment for the risk factors and the pattern of cognitive impairment (memory, attention and executive function decline). This enables an accurate diagnosis to be made at an earlier stage. Partial post-transplant cognitive impairment recovery is also important. Finally, doctors and patients alike face numerous ethical concerns and challenges regarding the transplantation of kidneys and other solid organs. In this review, we examined some key issues regarding cognitive impairment in kidney transplant patients. We focused on the mechanism of cognitive impairment in kidney transplant recipients, patterns of cognitive impairment; evaluation of patients with cognitive impairment for kidney transplantation, the potential impact of cognitive impairment on waitlisted and transplanted patients on patient care, non-pharmacological interventions and unmet medical needs, psychological and ethical issues in kidney transplantation, and unmet needs. As cognitive impairment in kidney transplant recipients is an underestimated, underrecognized but clinically relevant problem, screening for cognitive function before and after kidney transplantation would be worth considering in standard routine practice.

Keywords: chronic kidney disease; cognitive impairment; ethics; kidney transplantation; psychological issues.

Figure 1:

Mechanism of cognitive impairment in kidney transplant (KT) recipients.

Figure 2:

Pathway of CI in kidney transplant patients. This figure illustrates the critical aspects of cognitive impairment (CI) in kidney transplant (KT) patients. Top left box (Mechanism of CI in KT): This outlines the underlying mechanisms contributing to cognitive impairment in KT recipients, including small vessel disease, non-vascular risk factors (such as oxidative stress, chronic inflammation, hypercoagulability, and accumulation of uremic toxins), the impact of immunosuppressive therapy, and the presence of concomitant Alzheimer's disease. Bottom left box (Factors that independently influence CI in KT): This section identifies various independent factors that influence CI in KT patients. These include age, diabetes, hypertension, timing on hemodialysis/peritoneal dialysis before KT, glomerular filtration rate (GFR), donor type, lifestyle factors (e.g. smoking, alcohol, poor diet, obesity), depression, anxiety, frailty, level of education, marital status, and social engagement. Middle box (Rationale for screening in KT patients): This box emphasizes the rationale behind screening KT patients for CI. It highlights the high prevalence of CI in KT patients, which is 2–3 times higher than in the general population. CI in KT patients can lead to nonadherence, increased risk of rejection, graft loss, comorbidities, mortality, delirium, and coexisting conditions such as depression, fatigue, and reduced judgment capacity. Top right box (Screening): This section discusses the screening process for CI in KT patients, including the tests used (MoCA, MMSE with Trail Making Test B, DemTect, RBANS) and mentions that MoCA has been validated in patients on hemodialysis but not specifically in KT patients. It also advises that screening should be conducted shortly after the immediate post-transplant period and not restricted to specialized care teams. Bottom right box (What are the benefits): The final section outlines interventions for high-risk patients with CI in CKD and KT patients. Non-pharmacological interventions include nutritional guidance, physical activity, cognitive training, social activities, and monitoring vascular risk factors. Pharmacological interventions involve supplements with high doses of folate and vitamin D. Evidence-based treatments for CI in CKD include anemia management, controlling hyperparathyroidism (HPTH), antiplatelet agents, blood pressure-lowering treatments, lipid-lowering therapies, and antidiabetic drugs. Cholinesterase inhibitors and NMDA receptor antagonists are highlighted for Alzheimer's disease. These interventions aim to reduce CI progression, improve treatment adherence, and manage comorbidities. Hemodialysis (HD); peritoneal dialysis (PD); general practitioner; Montreal Cognitive Assessment (MoCA); Mini-Mental State Examination (MMSE); The Repeatable Battery for the Assessment of Neuropsychological Status; mild cognitive impairment (MCI); erythrocyte stimulating agents (ESA); hypoxia-inducible factor–prolyl hydroxylase inhibitors (HIF-PHIs).