PPMI

PPMI is an observational natural history study that follows people with Parkinson's disease, people at risk of it and healthy volunteers over many years to find markers of onset and progression for use in therapeutic trials. The Michael J. Fox Foundation launched it in 2010 together with academic and industry partners, and it has since been renamed the Parkinson's Precision Medicine Initiative. Clinical, imaging, biofluid, genetic and sensor data are released to approved researchers as they are collected, through the LONI Image and Data Archive.

Composition

The first phase enrolled 423 people with recently diagnosed, untreated Parkinson's disease, 196 healthy controls and 64 people whose clinical signs suggested Parkinson's but whose dopamine transporter scan was normal (SWEDD), at 24 sites in the US, Europe and Australia. About two thirds of each group were men, and mean age was around 61. The study has since added people with Parkinson's carrying LRRK2, GBA or SNCA variants (294 in the initial genetic phase), a prodromal cohort with risk features such as REM sleep behaviour disorder or reduced smell, and a further 600 untreated sporadic cases. The study design page plans about 5,500 clinical participants at around 50 sites. The counts in this entry cover the first phase only.

Acquisition

All participants had a brain MRI at baseline. Ten sites with a 3 T Siemens Trio followed a standardized protocol with a 3D MPRAGE and a cardiac-gated DTI sequence, repeated at follow-up for roughly half of the cohort; resting-state fMRI is flagged in the MRI metadata. Dopaminergic imaging used [123I]ioflupane SPECT (DaTscan), or [18F]AV-133 PET for VMAT-2 at the Australian site. Parkinson's participants were rescanned at 12, 24 and 48 months, healthy controls only at baseline.

Annotations

There are no voxel-level labels. The imaging core provides visual reads of each dopaminergic scan and striatal specific binding ratios for left and right caudate and putamen. Diagnoses, MDS-UPDRS and other clinical scores, biomarker results and genetic status are linked by participant number.

Known limitations

• The database is updated continuously without version control, so analyses must record the download date.
• Protocols, eligibility criteria and visit schedules changed between study phases.
• Only part of the cohort has the standardized MRI protocol; other sites acquired MRI to exclude non-Parkinson pathology.
• More than 90% of first-phase participants were white.