Plasma lipids metabolism in mild cognitive impairment and Alzheimer's disease.

Objectives: Expression of phospholipids and related molecules could provide panels of multiple biomarkers searching for the signature of Alzheimer's disease (AD). The aim of the present study was to quantify ten phospholipids and simultaneously determine phospholipase A ₂ (PLA ₂ ) activity in blood of mild cognitive impairment (MCI) and AD patients.
Methods: Thirty-four AD, 20 MCI and 25 controls were enrolled. The phospholipids where analysed using the AbsoluteIDQ ^® p180 Kit. PLA ₂ activities were accessed in platelets by a radio-enzymatic assay.
Results: The study failed to fix the ten phospholipids as a panel to predict AD; the levels of PCaaC36:6, PCaaC40:6 and C16:1-OH were lower in MCI than in controls (P = 0.041, P = 0.012, P = 0.044 respectively). PCaaC40:2 levels were lower in MCI than in AD (P = 0.041). The converters MCI-AD showed at baseline lower levels of PCaaC40:2 (P = 0.050) and PCaaC40:6 (P = 0.037) than controls. iPLA ₂ activity was reduced in AD and MCI than in controls (P < 0.001). We found positive correlation in the control group between PCaaC38:6 and tPLA ₂ (r = 0.680; P = 0.001) and sPLA ₂ (r = 0.601; P = 0.004); PCaaC40:1 and iPLA ₂ (r = 0.503; P = 0.020); PCaaC40:6 and tPLA ₂ (r = 0.532; P = 0.013) and sPLA ₂ (r = 0.523; P = 0.015).
Conclusions: Lipids metabolites in plasma might indirectly indicate changes in neuronal membrane and this deregulation can outline the transition between healthy and diseased brains.