Protective effect of unsaturated fatty acids on cognitive impairment in CKD patients: Results from the National Health and Nutrition Examination Survey (2011-2014)

Background: It is still unknown whether unsaturated fatty acids (UFA) have the same effect on preventing cognitive impairment in chronic kidney disease (CKD) patients as in healthy people.

Objective: To investigate the protective effect of dietary UFA intake and proportion on cognitive impairment in patients with CKD.

Methods: We extracted data from the National Health and Nutrition Examination Survey (NHANES, 2011-2014) on participants with a previous diagnosis of CKD and at least one complete cognitive assessment (Consortium to Establish a Registry for Alzheimer's Disease test, Animal Fluency Test and Digit Symbol Substitution Test). We used the lower quartile of the total scores of these three tests as the cut-off point, and divided the participants into two groups of normal cognitive performance and low cognitive performance to extract participants' intake of various UFA from the NHANES dietary module. The data were weighted using weighting parameters included in NHANES, and logistics regression and restricted cubic spline were used to analyze the protective effect of UFA intake on cognitive impairment in CKD participants.

Results: We found that participants with low cognitive performance all had significantly lower intakes of total monounsaturated fatty acids, total polyunsaturated fatty acids, ω-3 UFA, ω-6 UFA and ω-9 UFA than participants with normal cognitive performance (p< 0.05), and the ω-6 UFA and ω-9 UFA had the most significant protective effects on cognitive impairment of participants. We also discovered that oleic and linoleic acids play important roles in protecting against cognitive impairment in CKD participants. The protective effect of oleic acid, but not linoleic acid, on cognitive impairment showed a nonlinear relationship. The changes in the proportion of monounsaturated fatty acids to polyunsaturated fatty acids, ω-6 UFA to ω-3 UFA, and oleic acid to linoleic acid did not affect the risk of cognitive impairment in CKD participants.

Conclusions: UFA can reduce the risk of cognitive impairment in CKD patients, especially oleic acid and linoleic acid have a more obvious protective effect on cognitive impairment in patients with CKD. Among them, the protective effect of linoleic acid on cognitive impairment was continuously enhanced with the increase of intake, indicating that linoleic acid may be the most important UFA to reduce cognitive impairment in CKD patients.