The study investigates the breakdown of the blood-brain barrier (BBB) in the aging human hippocampus, a critical region for learning and memory. Using advanced dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), the researchers quantified regional BBB permeability in living human brains. They found that the BBB breakdown in the hippocampus worsens with age and mild cognitive impairment (MCI), correlating with injury to BBB-associated pericytes, as indicated by cerebrospinal fluid (CSF) analysis. The findings suggest that BBB breakdown is an early event in the aging brain, potentially contributing to cognitive impairment. The study highlights the importance of maintaining BBB integrity in the hippocampus to prevent cognitive decline.The study investigates the breakdown of the blood-brain barrier (BBB) in the aging human hippocampus, a critical region for learning and memory. Using advanced dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), the researchers quantified regional BBB permeability in living human brains. They found that the BBB breakdown in the hippocampus worsens with age and mild cognitive impairment (MCI), correlating with injury to BBB-associated pericytes, as indicated by cerebrospinal fluid (CSF) analysis. The findings suggest that BBB breakdown is an early event in the aging brain, potentially contributing to cognitive impairment. The study highlights the importance of maintaining BBB integrity in the hippocampus to prevent cognitive decline.