Serum biomarkers, modifiable risk factors, cognition, and processing speed in older adults

Cognitive impairment is a major public health concern in aging populations. However, most previous studies have examined serum biomarkers and lifestyle, psychosocial, and clinical factors in isolation, and their associations with global cognition and processing speed remain unclear. The aim of this study was to investigate the associations of serum biomarkers and lifestyle, psychosocial, and clinical factors with global cognition and processing speed among community-dwelling middle-aged and older adults.

This cross-sectional study analyzed data from community-dwelling adults aged ≥50 years who participated in the Gan-Dau Healthy Longevity Plan in Taiwan. Serum biomarkers were measured. Depressive symptoms were assessed using the 15-item Geriatric Depression Scale (GDS-15), and sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). Global cognition was assessed using the Montreal Cognitive Assessment (MoCA), and processing speed was assessed using the Digit Symbol Substitution Test (DSST). Multivariable linear regression models were used to examine the associations between serum biomarkers and lifestyle, psychosocial, and clinical factors and global cognition and processing speed after covariate adjustment.

A total of 992 participants (mean age: 67.23 ± 7.97 years; 74.9% women) were included. Serum creatinine was negatively associated with global cognition (B = -0.27; 95% CI -0.52 to -0.02; p = 0.032) and processing speed (B = -1.61; 95% CI -2.90 to -0.33; p = 0.014) after covariate adjustment. Depressive symptoms were also independently associated with both cognitive domains, whereas diabetes was associated only with processing speed.

Serum creatinine levels and depressive symptoms were independently associated with global cognition and processing speed. Diabetes was independently associated with processing speed only. These findings provide additional evidence regarding the associations of serum biomarkers and lifestyle, psychosocial, and clinical factors with cognitive performance. Further longitudinal studies are warranted to clarify the temporal relationships and potential clinical relevance of these associations.