Different Associations of Plasma Biomarkers in Alzheimer's Disease, Mild Cognitive Impairment, Vascular Dementia, and Ischemic Stroke.

Background and Purpose Cognitive and cerebrovascular diseases are common in the elderly, but differences in the plasma levels and associations of plasma biomarkers in these diseases remain elusive. Methods The present study investigated differences in plasma fatty acids [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)], adiponectin, reptin, plasma markers of inflammation [high-sensitivity C-reactive protein (hsCRP) and serum amyloid A (serum AA)], and plasma lipids [high-density lipoprotein and low-density lipoprotein (LDL)] in patients with Alzheimer's disease (AD) (n=266), mild cognitive impairment (MCI) (n=44), vascular dementia (VaD) (n=33), and ischemic stroke (IS) (n=200) in comparison to normal controls (n=130). Results The serological data showed that lower EPA and DHA levels and higher reptin and LDL levels were associated with AD and IS, the reptin/adiponectin ratio was strongly associated with IS, the hsCRP level was more strongly associated with VaD and IS, and the serum AA level was associated with all three cognitive diseases and IS. Conclusions This is the first report of differences in the expression levels of plasma biomarkers and peripheral arterial tonometry among AD, MCI, VaD, and IS patients and normal controls. These different associations indicate that diverse pathological mechanisms underlie these diseases.