An examination of the association of cognitive functioning, adherence to sodium restriction and Na/K ratios in Korean heart failure patients

Abstract

Aims and objectives Maintaining adequate ratios of sodium-to-potassium requires heart failure patients to be adherent to recommended dietary guidelines. A potential deterrent to adherence is poor cognitive functioning. The aims of this study were to (1) estimate dietary sodium and potassium intake and sodium-to-potassium ratios and (2) examine the associations between cognitive functioning and sodium-to-potassium ratios.

Background Cognitive impairment may impact levels of adherence and subsequently sodium-to-potassium ratios; however, little is known about the relationship of cognitive functioning, adherence to dietary restrictions and sodium-to-potassium ratios.

Design This study used a descriptive correlational design.

Methods Face-to-face interviews were conducted with heart failure patients with preserved or reduced left ventricular ejection fraction. Standard cognitive measures were used and included neuropsychological tests of global cognition, immediate and delayed recall, and executive function. Further, patients were instructed to complete a three-day food diary as an indirect measure of sodium-to-potassium intake.

Results Ninety-one Korean patients with heart failure participated in this study (age 57 years, women 33%, education 10 years). A major underlying cause for heart failure was dilated cardiomyopathy (40%), followed by ischaemic cause (24%); the mean heart failure duration was 37 months. Average sodium intake was 3982 mg/day, with men consuming a significantly higher amount than women (4207 vs. 3523 mg). Potassium intake was 2583 mg/day, with both men and women consuming similarly insufficient amounts. Sodium-to-potassium ratio was 1·60, with men having a significantly elevated ratio compared with women (1·68 vs. 1·44). Cognitive function by sodium-to-potassium quartile groups showed nonlinear associations.

Conclusion Participants in the study consumed excessive sodium and insufficient potassium; correspondingly, elevated sodium-to-potassium ratios showed significant associations with cognitive function (memory).

Relevance to clinical practice Dietary guidelines tailored to levels of cognitive function as well as Korean dining culture may be important in ensuring sodium-to-potassium balance in these heart failure patients.