Low Hemoglobin Levels Tied to Higher Risk of Cognitive Impairment in Hemodialysis Patients: Study
China: A new study published in BMC Nephrology has found a strong link between anemia and cognitive impairment (CI) in individuals undergoing maintenance hemodialysis (MHD), highlighting the potential importance of hemoglobin levels in preserving brain function among patients with end-stage renal disease (ESRD).
Conducted by Dr. Lin Huang and colleagues from the Blood Purification Center, Affiliated Yijishan Hospital of Wannan Medical College, China, the cross-sectional study analyzed data from 248 patients receiving regular hemodialysis.
Key findings were as follows:
- Nearly 34% of the participants were identified as having cognitive impairment based on their Mini-Mental State Examination (MMSE) scores, with cognitive impairment defined as a score below 24.
- The researchers observed that patients with higher hemoglobin levels—specifically those between 110 and 130 g/L or more—demonstrated significantly better cognitive performance. In contrast, those with hemoglobin levels below 90 g/L were found to be over 15 times more likely to exhibit cognitive impairment, even after adjusting for other influencing factors.
- Age, sex, blood pressure before dialysis, and uric acid levels were associated with cognitive function.
- Older age and lower diastolic blood pressure were linked to a higher likelihood of cognitive impairment, while male patients and those with higher uric acid levels seemed to have a reduced risk. These findings suggest a multifactorial influence on cognitive outcomes in hemodialysis patients.
Beyond hemoglobin levels, the study also examined a range of other variables such as education level, dialysis duration, comorbid conditions, serum albumin, creatinine, and interdialytic hypotension, all of which showed varying degrees of association with cognitive scores.
The authors pointed out that while anemia appears to be an independent factor associated with cognitive decline, the cross-sectional design of the study limits the ability to draw definitive conclusions about causality. They also noted several limitations, including the single-center setting, small sample size, and the use of the MMSE, which may not be sensitive enough to detect mild cognitive changes compared to other tools like the Montreal Cognitive Assessment (MoCA).
Despite these limitations, the study highlights the need for routine monitoring and effective management of hemoglobin levels in patients with ESRD on dialysis. Addressing anemia may not only improve physical health but also support cognitive well-being, which is essential for daily functioning and quality of life in this vulnerable population.
The researchers advocate for future multi-center, longitudinal studies with larger cohorts and more sensitive cognitive assessments to better understand the underlying mechanisms linking anemia and cognitive health in dialysis patients.
Reference:
Huang, L., Zhang, Y., Wang, J. et al. Association of anemia and cognitive impairment in patients undergoing maintenance hemodialysis: a cross-sectional study. BMC Nephrol 26, 387 (2025). https://doi.org/10.1186/s12882-025-04336-4
