Cerebrospinal fluid and blood Aß levels in Down syndrome patients with and without dementia: a meta-analysis study.

Abnormal ß-amyloid (Aß) levels were found in patients with Down syndrome (DS). However, Aß levels in patients with DS and DS with dementia (DSD) vary considerably across studies. Therefore, we performed a systematic literature review and quantitatively summarized the clinical Aß data on the cerebrospinal fluid (CSF) and blood of patients with DS and those with DSD using a meta-analytical technique. We performed a systematic search of the PubMed and Web of Science and identified 27 studies for inclusion in the meta-analysis. Random-effects meta-analysis indicated that the levels of blood Aß1-40 and Aß1-42 were significantly elevated in patients with DS compared with those in healthy control (HC) subjects. In contrast, there were no significant differences between patients with DS and those with DSD in the blood Aß1-40 and Aß1-42 levels. The CSF Aß1-42 levels were significantly decreased in patients with DS compared to those in HC subjects. Further, CSF Aß1-42 levels were significantly decreased in patients with DSD compared to those with DS, with a large effect size. Taken together, our results demonstrated that blood Aß1-40 and Aß1-42 levels were significantly increased in patients with DS while CSF Aß1-42, but not Aß1-40 levels were significantly decreased in patients with DS.