Re: “Metabolic Syndrome and Cognitive Performance Among Chinese ≥50 Years: A Cross-Sectional Study with 3988 Participants” by Chen et al. (Metab Syndr Relat Disord 2016;14:222–227)

Dear Editor,

We read with great interest a recently published article entitled “Metabolic Syndrome and Cognitive Performance Among Chinese ≥50 Years: A Cross-Sectional Study with 3988 Participants” by Chen et al., ¹ in which the authors who showed an excellent work enrolling a total of 3988 individuals concluded that deficits in cognitive function are likely related to diabetes and that they are also inversely associated with dyslipidemia in Chinese who are aged more than 50 years. Interestingly, this study also revealed a negative result that metabolic syndrome (MetS) is probably not a pivotal factor for the onset of cognitive impairment (CI). We appreciate these findings, and now would like to discuss several issues that are highly relevant to this study.

Accumulating evidence reveals that MetS is an independent risk factor for deficits in cognitive performance. ^2,3 In this study, Chen et al. suggested that MetS is not a risk factor for CI since net effects between diabetes and dyslipidemia could counteract each other. Nevertheless, we think it may be a false negative result because these two factors may not be overlapped in the same observed human subjects. In addition, obesity was excluded from a risk factor for CI that was solely dependent on statistical analysis of P value (0.054). It is likely, as mentioned previously, that altering inclusion criterion or removing several values with large deviation may get a distinct conclusion. Furthermore, as we know, CI and MetS are both aging-related disorders. It is commonly recognized that CI is a core symptom for Alzheimer's disease in patients who are mostly older than 65. The authors enrolled and analyzed human subjects aged more than 50. We suggested that if authors increased the age threshold to 65, MetS will be likely associated with CI. Collectively, large subsequent studies are required to elucidate whether MetS is a potential risk factor for the onset of CI.