Serum HDL Associated Antioxidant Activity in Alzheimer's Disease: Paraoxonase1 and Dysfunctional HDL

Human serum paraoxonase1 (PON1) is a high-density lipoprotein (HDL) associated antioxidant enzymes. We aimed to research the PON1 activity in Alzheimer's disease (AD) not accompanied with any disorders and other conditions influencing the PON1 activity.

We studied the PON1 activity and PON1 related lipid parameters in two groups, probable sporadic late onset AD (n:30) and those with healthy subjects (n:32). These groups were homogeneous, in which the subjects did not have any cardiovascular risk factors or other conditions affecting PON1 activity.

We found increased high-density lipoprotein cholesterol (HDL-C) and significantly decreased PON1 activity in the AD patients. A patient with a PON1 activity value of ≤ 151 U/L had a 5.48-fold higher risk for AD, compared to those with a PON1 activity value of > 151 U/L.

Decreased PON1 activity may play a role in the oxidative stress (OS) related pathogenesis of AD. An increased HDL-C with the decreased PON1 activity may bring the concept of dysfunctional HDL into question in the pathogenesis of AD. It may be emphasized in the pathogenesis of AD for further studies.