The cognitive profile and CSF biomarkers in dementia with Lewy bodies and Parkinson's disease dementia

Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) may be viewed as different points on a continuum reflecting the regional burden and distribution of pathology. An important clinical consideration is overlapping Alzheimer's disease (AD) pathology, since it has been reported that associated AD pathology in DLB shortens survival and leads to a more rapid cognitive decline. We aimed to investigate cerebrospinal fluid (CSF) biomarkers and the associated cognitive profile in DLB and PDD.Clinically diagnosed DLB (n=47) and PDD (n=17) patients from a clinical follow-up programme were investigated. All performed mini mental state examination (MMSE) and went through lumbar puncture at baseline. CSF concentrations of total τ (T-τ), τ phosphorylated at threonine 181 (P-τ(181) ) and the 42 amino acid isoform of amyloid β, Aβ42 were determined.We found significant differences in T-τ and Aβ42, with a higher level of T-τ and a lower level of Aβ42 in DLB compared to PDD. The combination of T-τ with Aβ42 showed better discrimination between DLB and PDD than either of the measures alone. In DLB, a CSF profile more like the one seen in AD was significantly correlated with worse performance on the orientation and memory of the MMSE.The correlation suggests a possible link between a higher degree of AD pathology and a profile of more temporal disabilities on cognitive tests in DLB. This might aid in identifying a subgroup of patients with a greater burden of AD pathology in a clinical setting and could have important implications for prognosis.