Relationship of the co-occurrence of sarcopenia and metabolic syndrome with cognitive trajectory deterioration in middle-aged and older adults: A national cohort study with causal forest analysis.

BACKGROUND

Cognitive impairment constitutes a major public health burden in the aging population. Sarcopenia and metabolic syndrome are both highly prevalent in middle-aged and older adults. However, the impact of their co-occurrence on long-term cognitive trajectories remains unclear.

OBJECTIVE

To investigate the association between the co-occurrence of sarcopenia and metabolic syndrome and adverse cognitive trajectories (including persistently low cognitive function, which may reflect baseline vulnerability, and rapidly declining function, which reflects prospective deterioration).

METHODS

A population-based cohort study was conducted using data from the China Health and Retirement Longitudinal Study 2011-2018. A total of 5985 participants aged 45 years or more were included. Latent class growth modeling was performed to identify distinct cognitive trajectories. Multinomial logistic regression was used to examine the associations between sarcopenia, metabolic syndrome, and their co-occurrence with cognitive outcomes. Causal forest analysis was applied to identify key effect modifiers and vulnerable subgroups.

RESULTS

Three cognitive trajectories were identified: persistently high, persistently low, and rapidly declining. The co-occurrence of sarcopenia and metabolic syndrome was associated with a 2.64-fold increased odds of participants experiencing the persistently low cognitive trajectory (95% confidence interval 1.49-4.68) and a 2.38-fold increased odds of the rapidly declining trajectory (95% confidence interval 1.03-5.47) in fully adjusted models. Sarcopenia on its own was associated with increased odds of adverse cognitive outcomes, whereas metabolic syndrome on its own showed no significant association. Age, body mass index, and hemoglobin level were the strongest effect modifiers.

CONCLUSION

The co-occurrence of sarcopenia and metabolic syndrome is a significant and modifiable risk factor for adverse cognitive trajectories. Metabolic syndrome on its own was not significantly associated with adverse cognitive trajectories in this sample after covariate adjustment, whereas the co-occurring phenotype showed a stronger association.