Decreased β-amyloid peptide42 in cerebrospinal fluid of patients with progressive supranuclear palsy and corticobasal degeneration

Several previous studies have identified biochemical markers for Alzheimer's disease (AD): cerebrospinal fluid (CSF)-β-amyloid peptide42 (CSF-Aβ42), CSF-total tau protein (CSF-tau) and CSF-phosphorylated tau protein (CSF-ptau). Progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) as well as AD are diseases with tauopathies. CSF-Aβ42, CSF-tau, and CSF-ptau have not been rigorously investigated in PSP and CBD. In the present study, we assessed CSF-Aβ42, CSF-tau, and CSF-ptau as biochemical markers for PSP and CBD, compared with AD. The subjects consisted of 18 cases of PSP, 9 cases with CBD, 69 cases with AD, and 43 control subjects. Genotyping or phenotyping of apolipoprotein E (apoE) was also performed. CSF-Aβ42 levels were significantly decreased in patients with PSP and CBD as well as in AD patients. The ratio of CSF-ptau to CSF-Aβ42 provided high diagnostic accuracy to distinguish both PSP from AD, and CBD from AD. ApoE genotype/phenotype was not associated with CSF-Aβ42 levels in all groups. We concluded that CSF-Aβ42 levels are reduced in PSP and CBD as well as in AD.