The relationship between plasma matrix metalloproteinase‐9 and cerebrospinal fluid biomarkers of tau is sex‐dependent

Matrix metalloproteinase‐9 (MMP‐9) is a proinflammatory, proteolytic enzyme that is dysregulated in Apolipoprotein (APOE) ε4 carriers, patients with mild cognitive impairment (MCI) and Alzheimer’s disease (AD) and has been shown to accelerate tau oligomerization, blood‐brain barrier breakdown and amyloid‐β (Aβ) accumulation. Evidence suggests that MMP‐9 activity may be regulated by sex hormones, yet it is unknown whether the association between plasma MMP‐9 and cerebrospinal fluid (CSF) AD biomarker levels varies by sex.