Table 2

Potential features to select study populations at high risk for phenoconversion, for disease-modifying clinical trials in RBD

AgeEqual or older than 65 years; or consider range between 55 and 75 years old36 37
RBD featuresLonger disease duration38 iRBD (ie, not due to narcolepsy, not due to brainstem lesion, not due to other known brain pathology)
RBD not occurring in temporal association with antidepressant medications
OlfactionDysfunction measured by the cross-cultural 12-item test37 39 40
CognitiveAbnormal performance assessed by neuropsychological testing41 42
MotorSubtle motor dysfunction: parkinsonism, ataxia and/or dysmetria measured by the part III of the Unified Parkinson’s Disease Rating Scale37 43 44
Abnormal motor performance assessed by objective testing (eg, Purdue Pegboard)
Colour visionAbnormal colour vision assessed by FM-100
AutonomicAutonomic dysfunction: constipation, urinary symptoms, erectile dysfunction, orthostatic hypotension36 45 46
Dopamine imagingDaT SPECT: reduced nigrostriatal dopaminergic binding in the putamen and striatum47 48
GeneticGBA mutation49 or other genotype that increases phenoconversion risk
OtherSee section of Outcome Measures for Symptomatic Trials below
or symptomatic trials section for discussion of imaging, biofluid and other potential selection biomarkers in development
  • DaT, Dopamine transporter SPECT; FM-100, the Farnsworth Munsell 100 HueColor Vision Test; GBA, glucocerebrosidase ; iRBD, isolated rapid eye movement sleep behavioural disorder; RBD, rapid eye movement sleep behavioural disorder; SPECT, single-photon emission CT.