Patients’ clinical features.

FOG–P: Patients with freezing of gait (FOG) with little to no parkinsonism.

PD–FOG: Patients with Parkinson’s disease without FOG.

FOG onset: The time from symptom onset to FOG onset.

UPDRS: Unified Parkinson’s disease rating scale.

Axial: The total of standing, posture, gait and postural instability items.

Upper limb movement: The total of upper limb repetitive movement items.

Lower limb movement: The total of lower limb repetitive movement items.

Rigidity: The total rigidity score for the neck and limbs.

Tremor: The total tremor score for the neck and limbs.

NFOG-Q: New freezing of gait questionnaire.