Background The clinical diagnosis of dementia with Lewy bodies (DLB) is made on the basis of consensus criteria; however, the sensitivity of the criteria is relatively low. There are no generally accepted biomarkers to distinguish DLB from other dementias. Here the utility of quantification of a-synuclein, beta-amyloid42 (A beta 42) and tau in the CSF of patients with DLB, Alzheimer's disease (AD) and other dementias was examined.
Methods 86 patients were divided into three age and sex matched groups: DLB (n=34), AD (n=31) and other dementias (n=21). Two patients with alpha-synuclein gene (SNCA) duplication were also examined. A beta and tau were quantified using an ELISA kit. A modified sandwich ELISA was developed which enables the sensitive quantification of CSF alpha-synuclein.
Results Total and phosphorylated tau levels as well as A beta 40/42 and tau/A beta 42 ratios were significantly higher in AD patients than in patients with DLB (p<0.01) and other dementias (p<0.01). CSF alpha-synuclein levels in DLB patients were significantly lower than those in patients with AD (p<0.05) and other dementias (p<0.01). CSF alpha-synuclein level correlated with the A beta 42 level in DLB patients (p=0.01, r=0.43). Two patients with SNCA duplication exhibited relatively low levels of CSF alpha-synuclein.
Conclusions The study suggests that reduced levels of CSF alpha-synuclein in DLB may reflect the accumulation of alpha-synuclein with Lewy pathology in the brain and that quantification of CSF alpha-synuclein helps in the differentiation of DLB from AD and other dementias in combination with A beta 42 and tau analysis.