Superoxide Dismutase Modified the Association of Serum Malondialdehyde Levels with Cognitive Decline Among Older Adults: Findings from the Chinese Longitudinal Healthy Longevity Survey.

BACKGROUND: Numerous studies have investigated the correlation between malondialdehyde (MDA) and cognitive decline. However, limited research has explored the interplay between superoxide dismutase (SOD), C-reactive protein (CRP), and MDA.

OBJECTIVE: This study aims to scrutinize the association between MDA and cognitive function in older adults, while also elucidating the roles of SOD and CRP within this relationship.

METHODS: Utilizing data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) spanning 2008-2009, 2011-2012, and 2014, this study included 2,696 eligible subjects. Cognitive function was evaluated using the Chinese version of the Mini-Mental State Examination (MMSE). Linear mixed-effects models were employed to examine the links between MDA, SOD, CRP, and their interactions with cognitive function.

RESULTS: Elevated serum levels of MDA and CRP, as well as decreased serum SOD levels, were related to decreased cognitive function (β= -0.220 and -0.346, 95% CI: -0.399, -0.041 and -0.526, -0.167 for MDA and CRP; β= 0.384, 95% CI: 0.204, 0.564 for SOD). Notably, a significant interaction between MDA and SOD was detected (p = 0.001). An increase per standard deviation in serum MDA levels was significantly associated with a 0.347-point lower MMSE score only in participants with normal cognitive function and high SOD levels (β= -0.347, 95% CI: -0.497, -0.197; p <  0.001).

CONCLUSIONS: Elevated serum MDA levels in the normal population with high SOD levels suggested diminished cognitive performance. Combining MDA with SOD could be pivotal in identifying older adults at risk of cognitive decline in clinical settings.