Poor Bone Health Associated with Reduced Cerebral Perfusion and Brain Volume in Older Adults

<b>Background:</b> Bone health and brain function may be closely interconnected through a complex bone-brain axis. The relationship between bone mineral density (BMD), vertebral perfusion, marrow composition, cerebral perfusion, brain volume, and cognitive decline, however, remain incompletely understood. <b>Methods:</b> Ninety-nine female subjects (mean age 65.00 ± 5.00 years) with clinically suspected mild cognitive impairment underwent dual-energy X-ray absorptiometry, carotid ultrasound, and multimodal magnetic resonance imaging (MRI) of the brain and lumbar spine to measure BMD, bone perfusion, marrow fat content as well as cerebral perfusion, cerebral volume, cerebral white matter burden and large vessel atherosclerosis. Cognitive function was assessed using the Hong Kong Montreal Cognitive Assessment (HK-MoCA). Bone, cerebral, vascular, and cognitive measures were correlated using Spearman correlation coefficients and compared in group comparisons. <b>Results:</b> Lower BMD was correlated with reduced subcortical cerebral blood flow (CBF) (r = 0.27, <i>p</i> = 0.031) and lower total brain parenchymal volume (r = 0.25, <i>p</i> = 0.021). Reduced bone marrow perfusion and increased marrow fat content were also associated with lower total brain parenchymal volume (r = 0.24, <i>p</i> = 0.023 and r = -0.26, <i>p</i> = 0.025). Subjects with the lowest L3 vertebral body perfusion or highest marrow fat content had significantly reduced total brain and hippocampal volumes (<i>p</i> = 0.029-0.049) compared with those with the highest perfusion or lowest marrow fat content. <b>Conclusions:</b> This study shows an association between lower BMD, reduced vertebral perfusion, and increased marrow fat with reduced brain parenchymal volumes and reduced brain perfusion. Further studies are warranted to clarify these relationships and explore the underlying shared mechanisms affecting bone health and cerebral microvascular and structural brain changes.