Influence of plasma matrix metalloproteinase levels on longitudinal changes in Alzheimer's disease (AD) biomarkers and cognitive function in patients with mild cognitive impairment due to AD registered in the Alzheimer's Disease Neuroimaging Initiative database

The present study investigated the effects of plasma matrix metalloproteinases (MMPs) on longitudinal changes in Alzheimer's disease (AD)-related biomarkers in cerebrospinal fluid (CSF), brain atrophy, and cognitive function in patients with mild cognitive impairment due to AD (MCI-AD). We used data from the Alzheimer's Disease Neuroimaging Initiative database. We included 95 ApoE4-positive patients with MCI-AD who were confirmed to have low Aβ42 and/or high phosphorylated-tau (p-tau) in CSF. We obtained baseline demographic data, plasma MMP levels, including MMP-1, −2, −7, −9, −10, and tissue inhibitor of MMP-1 (TIMP-1), longitudinal annual data on Aβ42, total tau, and p-tau in CSF, MRI-measured hippocampal volumes, and cognitive function evaluated by the Mini-Mental State Examination (MMSE) and AD Assessment Scale-11 (ADAS-11) over 4 years. We examined the effects of baseline MMP levels on longitudinal changes in CSF AD biomarkers, hippocampal volumes, and cognitive function using a linear mixed regression analysis. No significant differences were observed in baseline plasma MMP levels between MCI-AD patients and control subjects, except for MMP-10, which was significantly lower in MCI-AD than in controls. The baseline levels of MMPs did not correlate with longitudinal changes in CSF biomarkers. Declines in hippocampal volumes and cognitive function evaluated by MMSE and ADAS-11 were significantly faster in MCI-AD patients with high-MMP-9 levels at baseline than in those with middle and low MMP-9 levels at baseline. High plasma MMP-9 levels in MCI-AD patients might enhance neurodegeneration and cognitive decline. •We examined the effects of MMPs on longitudinal changes in AD-biomarkers in MCI-AD.•The baseline MMP levels did not correlate with longitudinal changes in CSF Aβ or tau.•Declines in hippocampal volumes were faster in MCI-AD with high-MMP-9 levels.•Declines in cognitive function was faster in MCI-AD with high-MMP-9 levels.