Murray AM et al. (2006) Cognitive impairment in hemodialysis patients is common. Neurology 67: 216–223

Patients on hemodialysis are at high risk of cognitive impairment because of their older age and high prevalence of stroke and cardiovascular risk factors. Murray et al. investigated cognitive function in a cohort of hemodialysis patients to identify factors that might be associated with cognitive impairment.

In total, 374 patients aged ≥55 years who had been on maintenance hemodialysis for at least 2 months underwent cognitive tests that investigated memory, executive function and verbal fluency domains. A cognitive impairment algorithm, which required completion of tests in at least two of these domains, was used to classify subjects as having mild, moderate or severe cognitive impairment, or normal cognitive function.

Of the 338 patients who completed tests in at least two domains, 43 (13%) were classified as having normal cognition, and 47 (14%) as having mild, 122 (36%) as having moderate and 126 (37%) as having severe cognitive impairment; only 2.9% had a documented history of cognitive impairment. In adjusted models, equilibrated Kt/V >1.2 (a marker of dialysis adequacy), history of stroke and ≤8 years of education were associated with severe cognitive impairment (P <0.05 for all). Hemoglobin level <110 g/l was of borderline significance (P <0.08). Risk of severe cognitive impairment was significantly higher in a random sample of 101 of the 338 hemodialysis patients than in 101 age-matched non-dialysis patients (adjusted odds ratio 3.54; P <0.02).

The authors conclude that moderate to severe cognitive impairment is common in hemodialysis patients, and that improved detection of such impairment is needed. Further studies are required to ascertain whether cognitive impairment is caused solely by the underlying disease, or if it is worsened by hemodialysis.