Clinical predictors of individual cognitive fluctuations in patients undergoing hemodialysis

Background: Cognitive impairment in hemodialysis (HD) patients is frequent and mediated by several factors. It is unclear which patients are more susceptible to cognitive variations around the dialysis cycle and which clinical factors may play a mediator role. We aimed to answer these issues by investigating intraindividual changes within the dialysis cycle.

Study design: Cross-sectional observational study with repeated measures.

Setting & participants: 47 HD patients and 40 controls without kidney disease, both without history of neurologic disease.

Predictors: Dialysis vintage, disease duration, vascular risk factors, comorbidity index score, intradialytic weight change, frequency of hypotensive episodes, and biochemical levels (hemoglobin, leukocytes, urea, creatinine, sodium, and potassium). Covariates included demographics (age, education, and sex).

Outcomes & measurements: Significant individual deterioration in attention and executive functions (phasic and intrinsic alertness, Stroop test, and Trail Making Test) after dialysis, as measured by a regression-based reliable change method. Regression models were used to identify clinical predictors of individual cognitive decline after dialysis.

Results: After dialysis, patients primarily showed prolonged reaction times and psychomotor slowing. However, individual-based analyses revealed that fluctuations in attention and executive functions were present in only a minority of patients. Significant individual fluctuations on particular attention and executive tasks were associated moderately with intradialytic hypotensive episodes, as well as with psychoactive medication, and were predicted weakly by blood leukocyte count, sodium level, dialysis vintage, and volume.

Limitations: Small sample size; patient group younger and healthier than the overall HD population, limiting generalizability.

Conclusions: Only a minority of patients exhibit significant individual cognitive fluctuations, predominantly showing deterioration after dialysis in attention and executive functions. Susceptibility to such fluctuations was predicted in part by both HD-dependent and -independent factors.