In the present study we evaluated, by high-speed liquid chromatography/tandem mass spectrometry, the plasma levels of 24S-OH-Chol in a sample of older individuals affected by LOAD, VD, or cognitive impairment no dementia (CIND); successively, we investigated the possible association between the PPARgamma Pro12Ala polymorphism and 24S-OH-Chol levels. The gene discussed is PPARG; the disease is dementia.