Effects of saturated and monounsaturated fatty acids on cognitive impairment: evidence from Mendelian randomization study.

ABSTRACT

BACKGROUND: Prior observational studies have suggested correlations between saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) with cognitive function. However, causal relationships remains unclear. METHODS: We assessed the causal impact of two SFAs (palmitic acid [PA] and stearic acid [SA]) and two MUFAs (oleic acid [OA] and palmitoleic acid [POA]) on cognitive function-related traits, and dementia-related traits by univariable Mendelian randomization (UVMR) and multivariable Mendelian randomization (MVMR) analyses. RESULTS: UVMR indicated ß of 0.060 (P = 4.05E-06) for cognitive performance score and 0.066 (P = 4.21E-04) for fluid intelligence per standard deviation (SD) increase in OA level. MVMR indicated (i) ß of -0.608 (P = 8.37E-05) for fluid intelligence score per SD increase in POA; (ii) ß of 0.074 (P = 0.018) for fluid intelligence score per SD increase in OA; (iii) ß of 0.029 (P = 0.033) for number of incorrect matches in round per SD increase in PA; and (iv) ß of 0.039 (P = 0.032) for number of incorrect matches in round per SD increase in SA. In addition, a secondary MVMR analysis after excluding the effect of polyunsaturated fatty acids suggested that (i) ß of -0.043 (P = 1.97E-02) for cognitive performance score per SD increase in PA and (ii) ß of -0.079 (P = 1.79E-03) for cognitive performance score per SD increase in SA. CONCLUSIONS: Overall, UVMR and MVMR suggest that OA may be beneficial for cognitive function, while POA, PA, and SA may have detrimental effects on cognitive function.