A CASE-CONTROL STUDY: COGNITIVE IMPAIRMENT IN CHRONIC KIDNEY DISEASE (CKD)

Introduction- Cognitive impairment (CI) is a significant concern in patients with chronic kidney disease (CKD), yet its relationship with CKD severity and associated factors remains underexplored. CKD is a progressive condition characterized by persistent kidney damage or an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² for at least three months. As CKD progresses, it leads to various complications, including cardiovascular disease, metabolic dysfunction, and, notably, cognitive decline, which significantly contributes to morbidity. The global prevalence of CKD continues to rise, and cognitive impairment in these patients is associated with a poorer quality of life, reduced adherence to treatment, and increased morbidity and mortality. This study aims to evaluate cognitive function in CKD patients of Indian descent, investigating its correlation with CKD severity, biochemical markers, and cardiovascular risk factors. Understanding these relationships is crucial for improving early diagnosis and management strategies to mitigate the burden of cognitive dysfunction in CKD. Materials and Methods- This case-control study was conducted from September 2023 to March 2024 at Indira Gandhi Government Medical College & Hospital, Nagpur. We recruited 100 CKD patients from the Medicine OPD/IPD, CKD clinic, and Dialysis Center, and matched them with 100 healthy controls based on age, gender, and educational status. Inclusion criteria for CKD patients included an eGFR <60 ml/min/1.73 m² and age between 18 and 75 years. Controls were healthy individuals or their relatives attending the hospital, excluding those with CKD or cognitive-affecting conditions. Cognitive impairment was assessed using the MMSE, with scores categorized as severe (≤9), moderate (10–18), or mild (19–23). eGFR was classified into four groups: stage 3A+3B, stage 4, stage 5 non-dialysis, and stage 5 on hemodialysis. Results- The study identified chronic kidney disease (CKD) as an independent and significant risk factor for cognitive impairment. Multivariate analysis revealed that CKD patients had substantially higher odds of cognitive decline, with an odds ratio of 7.87 (95% CI: 4.04–15.36, p < 0.001) indicating a strong association. Cognitive impairment was significantly more prevalent in CKD patients (60%) compared to controls (16%) (p < 0.001). The mean MMSE score for CKD patients was significantly lower (22.0 ± 4.61) compared to controls (27.08 ± 3.29). CKD patients had significantly reduced eGFR (mean 17.9 mL/min/1.74 m²) compared to controls (103 mL/min/1.74 m²) (p < 0.001), with lower eGFR strongly associated with worse cognitive function (p < 0.001). Hypertension (78%) and diabetes mellitus (42%) were the most common comorbidities in CKD patients found to have significant association to cognitive decline. Multivariate linear regression analysis revealed that eGFR, HDL, and total cholesterol are significant predictors of cognitive impairment in CKD patients (p = 0.041 for HDL; p = 0.048 for total cholesterol). These findings suggest that CKD is a significant and independent risk factor for cognitive decline, influenced by both renal and metabolic factors, including hypertension, diabetes, and lipid parameters. Discussion- This study underscores chronic kidney disease (CKD) as a significant independent risk factor for cognitive decline, with CKD patients being 7.87 times more likely to experience cognitive impairment compared to controls (OR: 7.87, 95% CI: 4.04–15.36, p < 0.001). A positive correlation between eGFR and MMSE scores further links declining kidney function to worsening cognitive performance. Additionally, higher HDL cholesterol levels were associated with better cognitive outcomes, while higher total cholesterol levels were inversely related to cognitive function. Hypertension and diabetes, common comorbidities in CKD, were also strongly associated with cognitive impairment. These findings suggest that early interventions targeting kidney function i.e. eGFR, lipid profiles, and traditional risk factors could help mitigate cognitive decline in CKD patients.