The effect of the interdialytic interval on cognitive function in patients on haemodialysis.

Background: Cognitive deficits are common among individuals on haemodialysis (HD). The degree of dysfunction may shift over the course of the interdialytic interval.

Objectives: To use ecological momentary assessment (EMA) to examine the relationship between the length of the interdialytic interval and reports of cognitive dysfunction.

Design: A quantitative study whereby each patient's cognitive functioning was measured during both short and long interdialytic intervals.

Participants: Adults maintained on HD (Female n = 15, Male n = 11; M  = 42.7 ± 15.8 years) were drawn from a standalone HD unit within a large university medical centre.

Measurements: Tests of baseline neurocognitive functioning were undertaken (Mini-Mental Status Examination, Digit Span, California Verbal Learning Test, Benton Visual Retention Test, Trail-Making Test) and smartphone-based electronic diary reports of cognitive impairment were made around six times each day for one week.

Results: Cognitive function and aptitude in this sample, although low, did not reflect clinically-significant impairment, with a mean Mini-Mental Status Exam score of 25.7 ± 3.0. Diary reports of cognitive impairment were also minimal, with an overall mean rating of .22 out of 5. Contrary to expectations, cognitive impairment was significantly greater on the one-day interdialytic days than on Day 2 of the two-day interdialytic interval (β = .094, p = .017).

Conclusions: Although cognitive impairment appears to be mild in stable, young patients with end stage renal disease, volumetric disruptions caused by HD may exacerbate such dysfunction.