Silent Lacunar Infarcts Are Associated With Decreased Physical Function and Muscle Mass Among Japanese Older People: The Bunkyo Health Study

Background Silent lacunar infarcts (SLIs) are asymptomatic subcortical infarcts detected on brain magnetic resonance imaging (MRI) and are associated with the risk of stroke and cognitive decline. The relationship between SLIs and physical performance and skeletal muscle mass in community‐dwelling older adults remains unclear. We examined whether SLI is associated with physical performance and muscle mass in older Japanese adults. Methods We conducted a cross‐sectional analysis of 1540 community‐dwelling adults aged 65–84 years from the Bunkyo Health Study with no prior stroke. SLIs were defined as 3‐ to 15‐mm infarcts on MRI and categorized as none, single or multiple. Physical performance was assessed using knee extensor and flexor strength, handgrip strength, maximum gait speed, two‐step test, the timed up and go (TUG) test and one‐leg standing test. Muscle mass was assessed using dual‐energy X‐ ray absorptiometry (DXA) derived appendicular skeletal muscle index (SMI ht ), body mass index (BMI) adjusted SMI (SMI BMI ) and calf circumference. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA). A multivariable linear regression model was used to analyse SLI as an ordinal variable (none, single or multiple) with multiple adjustments. Results Among 1540 participants (mean age: 73.0 ± 5.4; 58.8% female), 254 (16.5%) had SLIs. Among those with SLIs, 184 (72.4%) had multiple infarcts. Higher SLI burden was associated with older age, higher BMI and waist circumference, higher prevalence of hypertension and lower cognitive function ( p for trend < 0.001). In adjusted analyses, increasing SLI burden was associated with lower knee extensor strength ( B = −1.92 Nm, 95% confidence interval [CI] = −3.32 to −0.51, p = 0.008), lower knee flexor strength ( B = −1.52 Nm, 95% CI = −2.39 to −0.65, p < 0.001), lower handgrip strength ( B = −0.33 kg, 95% CI = −0.63 to −0.04, p = 0.029), slower maximum gait speed ( B = −0.03 m/s, 95% CI = −0.05 to −0.01, p = 0.005), longer TUG time ( B = 0.22 s, 95% CI 0.12–0.32, p < 0.001) and lower two‐step test performance ( B = −0.02, 95% CI −0.03 to −0.01, p < 0.001). Higher SLI burden was also associated with lower SMI ht ( B = −0.04 kg/m 2 , 95% CI = −0.08 to −0.00, p = 0.047), lower SMI BMI ( B = −0.01, 95% CI −0.01 to −0.00, p = 0.025) and smaller calf circumference ( B = −0.18 cm, 95% CI −0.31 to −0.05, p = 0.006). Conclusions Among community‐dwelling older Japanese adults, greater SLI burden was independently associated with impaired physical performance and lower muscle mass. Further longitudinal studies are required to clarify temporal relationships and mechanisms.