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

Only 26 adults were studied, and 17 refused enrolment, withdrew, expired, or provided insufficient data; none of the dropped subjects had private insurance, so the findings may not apply to other dialysis patients. The sample was mostly Hispanic or Latino, and the paper says this group may have specific risk factors for kidney failure that make them less comparable with other groups. Many participants were uncomfortable with smartphones or tablets, and low adherence was sometimes due to inability to use the diary system, which may have reduced the quality of the data. Self-reported cognitive problems were very mild overall, and the authors say this makes it difficult to draw a firm conclusion about the effect of time since dialysis. The diary items were adapted from standard quality-of-life and depression scales, but the paper says it is not known whether they are sensitive enough for momentary cognitive changes.

Do not read this as proof that a longer gap between dialysis sessions improves thinking or that dialysis causes clinically important cognitive impairment. The sample was small, the reported cognitive problems were very mild, and only reaction time showed a difference across intervals.