Etiology-Phenotype-Outcome Pathway Study on Freezing of Gait (FOG)

Freezing of gait (FOG) is a common and disabling gait disturbance characterized by a transient inability to initiate or maintain effective stepping. It is most frequently observed in Parkinson's disease but can also occur in other parkinsonian syndromes and neurological conditions associated with gait and balance dysfunction. Freezing of gait is associated with falls, loss of independence, reduced quality of life, and increased caregiver burden, yet its underlying mechanisms, clinical heterogeneity, and long-term trajectories remain incompletely understood.

This study is a prospective, multicenter, observational patient registry designed to systematically collect longitudinal clinical data from adults with freezing of gait, gait and balance impairment, or those at high risk for developing freezing of gait. Participants will be recruited from neurology and related specialty clinics at participating centers and followed over time as part of routine clinical care.

The registry will collect a broad range of clinical information, including but not limited to:

Demographic and clinical characteristics; Freezing of gait severity and related symptoms; Objective gait parameters and balance performance assessed using standardized gait tasks; Motor symptom severity and functional status; Falls and fall-related outcomes; Health-related quality of life and other patient-reported outcomes. Clinical assessments will be performed at baseline and during scheduled follow-up visits over a planned follow-up period of up to 36 months. Data collection may include questionnaires, clinician-rated scales, objective gait and balance assessments, and video-based evaluations, depending on local clinical practice and participant capability.

This registry is non-interventional. All diagnostic and therapeutic decisions, including medication adjustments and rehabilitative interventions, will be made solely by the treating physicians according to standard clinical practice. The study does not mandate any experimental drugs, devices, or procedures.

The primary objectives of this registry are to:

Characterize the longitudinal course and clinical variability of freezing of gait; Examine associations between freezing of gait, gait and balance impairment, falls, and clinical outcomes; Identify potential clinical phenotypes and risk factors associated with worsening gait dysfunction and adverse outcomes.

The findings from this registry are intended to support hypothesis generation, improve clinical risk assessment, and provide a foundation for the development of future mechanistic studies and interventional trials targeting freezing of gait and related gait disorders.

Inclusion criteria

• Age 30-85 years
• Presence of freezing of gait or non-freezing gait or balance impairment
• Diagnosis of Parkinson's disease or related parkinsonian disorders according to established international criteria (including PD, PSP, MSA, DLB, CBD, vascular parkinsonism, or idiopathic normal pressure hydrocephalus)
• Ability to complete gait and balance assessment tasks independently or with assistance
• Ability and willingness to provide written informed consent

Exclusion criteria

• Severe dementia (Mini-Mental State Examination score < 10)
• Severe psychiatric disorders interfering with study participation
• Severe cardiopulmonary, musculoskeletal, or other medical conditions significantly affecting gait safety
• Stroke, fracture, or other major medical events within the past 3 months
• Inability to comply with follow-up procedures
• Refusal of video or speech data collection