The cerebrospinal fluid (CSF) plays an important role in homeostasis of the brain. We previously demonstrated that major CSF
proteins such as
lipocalin-type
prostaglandin D2 synthase (L-PGDS) and
transferrin (Tf) that are biosynthesized in the brain could be
biomarkers of altered CSF production. Here we report that the levels of these brain-derived CSF
proteins correlated well with each other across various
neurodegenerative diseases, including
Alzheimer's disease (AD). In addition,
protein levels tended to be increased in the CSF samples of AD patients compared with the other diseases. Patients at memory clinics were classified into three categories, consisting of AD (n = 61),
mild cognitive impairment (MCI) (n = 42), and cognitively normal (CN) (n = 23), with MMSE scores of 20.4 ± 4.2, 26.9 ± 1.7, and 29.0 ± 1.6, respectively. In each category, CSF
protein levels were highly correlated with each other. In CN subjects, increased CSF
protein levels correlated well with those of AD markers, including
amyloid-β and
tau protein, whereas in MCI and AD subjects, correlations declined with AD markers except p-tau. Future follow-up on each clinical subject may provide a clue that the CSF
proteins would be AD-related
biomarkers.