As a result of the Parkinson Progression Marker Initiative (PPMI), several promising biomarkers have been identified.
A comparison of cerebrospinal fluid (CSF) was carried out between, (a) patients with PD suffering from mild cognitive impairment at the time of enrolment, (b) patients with PD who were cognitively intact, and (c) healthy control participants who were cognitively intact.1 A lower level of α-synuclein in CSF was associated with poorer overall cognition, particularly in relation to executive–attentional domains.1 This suggests that α-synuclein might play a role in the development of cognitive impairment in PD.1 Kang and colleagues evaluated CSF biomarkers specifically in de novo participants with PD – i.e., those who had not yet received any medication for their disorder.2 They found several biomarkers associated with PD (amyloid-β, total-tau, phosphorylated tau181, and α-synuclein).2 The authors proposed that these biomarkers could potentially be used to facilitate a diagnosis of PD during its early stages.2
More recently, data from the PPMI study have been used to assess the α-synuclein seed amplification assay, and to compare clinical features and dopamine transporter imaging characteristics of people with LRRK2 and GBA mutations without clinical PD.4,5 This analysis showed that there are subtle motor and non-motor signs in this population, despite the fact that only 11% of the LRRK2 mutation carriers and 3% of the GBA mutation carriers had a clear dopamine transporter deficit when imaged.4