Reduced cardiac vagal modulation is associated with visuospatial working-memory inefficiency in older adults with type 2 diabetes mellitus: a cross-sectional exploratory study

Older adults with Type 2 Diabetes (T2D) are at increased risk for cognitive decline, particularly in executive and working-memory processes that support everyday functioning. Visuospatial working-memory binding (VSWMB), which involves integrating object identity and spatial location, may be especially vulnerable to age- and diabetes-related cognitive changes. Heart rate variability (HRV), an index of cardiac vagal modulation, has been associated with cognitive functioning in aging populations; however, its relationship with VSWMB in older adults with T2D remains unclear. This exploratory study examined associations between vagal modulation and VSWMB efficiency in older adults with T2D. Twenty-five older outpatients with T2D (mean age = 73.8 ± 6.1 years) underwent electrocardiographic assessment at rest, during, and following a visuospatial binding task (VBT) visuospatial binding task (TNABV). Cardiac vagal modulation was indexed using the root mean square of successive differences (RMSSD). Correlational analyses, group comparisons, and exploratory receiver operating characteristic (ROC) analyses were conducted. Resting RMSSD was positively associated with TNABV Efficiency Index 3, the most cognitively demanding visuospatial binding condition ( r = .53, p = .007), and task-averaged RMSSD showed a similar association ( r = .44, p = .034). Participants with impaired binding performance exhibited lower resting RMSSD (U = 19, Z = 2.95, p = .002) and lower task-averaged RMSSD (U = 31, Z = 1.98, p = .046) than those without impairment. Exploratory ROC analyses indicated that resting RMSSD discriminated participants with and without binding impairment (AUC = 0.86, sensitivity = 0.80, specificity = 0.79). No significant associations were observed for heart rate measures. These findings provide preliminary evidence that reduced cardiac vagal modulation is associated with poorer visuospatial working-memory binding efficiency in older adults with T2D. The results support further investigation of autonomic regulation as a correlate of cognitive functioning in metabolic aging and suggest that HRV may help identify older adults with T2D who are more vulnerable to cognitive inefficiency.