Amyloid-β and τ biomarkers in Parkinson's disease-dementia

Dementia is a frequent and devastating non-motor complication of advanced Parkinson's disease (PD). There is growing evidence of a synergistic role of Alzheimer's-type brain lesions containing tau and amyloid-beta (A beta) proteins and cortical Lewy aggregates in PD-related dementia (PDD). Therefore, biomarkers of both tau and A beta may be seen as diagnostic and predictive markers of PDD. Here, we review the available studies in PD and PDD using cerebrospinal fluid (CSF) total tau, phospho-tau, and/or A beta levels, and PET probes targeting Alzheimer's-type lesions. Overall, high CSF tau and phospho-tau levels and/or low CSF A beta levels have been found in part of PDD patients, and a longitudinal study has found greater worsening in cognitive performance over time in nondemented PD patients with low baseline CSF A beta levels. Few studies are available on the use of PET imaging in PD, all of them using the Pittsburgh B compound (PIB), and with figures of about 30% of scans with PIB uptake in the AD-range in PDD. we conclude that these CSF and PET markers deserve further evaluation as candidate biomarkers of dementia in PD. According to this, we are currently undertaking a longitudinal project on the predictive value of dementia of the combined use of CSF tau and A beta and F-18-FDDNP PET in PD. (C) 2011 Elsevier B.V. All rights reserved.