High fear-of-falling in Parkinson's disease: Distinct clinical phenotypes with motor and non-motor dominance.

BACKGROUND

Fear-of-falling (FOF) in Parkinson's disease (PD) reflects both motor and non-motor determinants and is associated with reduced quality of life (QoL). However, its dominant clinical drivers in highly concerned patients remain unclear.

OBJECTIVE

To identify and characterize distinct clinical phenotypes underlying high fall-related concern in PD.

METHODS

In this cross-sectional study of 460 PD patients, FOF was assessed with the Falls Efficacy Scale-International (FES-I). Independent correlates were identified via stepwise regression. Patients with high FES-I (≥28; n = 199) were classified into phenotypes according to their predominant predictor: motor daily-living disability (MDS-UPDRS II), anxiety (HAM-A), or OFF-state gait impairment.

RESULTS

In the full cohort, FES-I was most strongly associated with MDS-II, anxiety, freezing severity, body bradykinesia, and constipation (R2 = 0.334). In the high-FES-I subgroup, MDS-II and anxiety remained significant, while gait-OFF emerged as a significant predictor (R2 = 0.319). Phenotypic analysis identified three subgroups: motor-disability-driven (n = 58; marked functional limitations, higher postural/gait impairment, and despite expectations, greater freezing severity than the gait-impairment group), anxiety-driven (n = 63; mild motor deficits but high affective burden), and gait-impairment-driven (n = 37; severe axial gait deficits with relatively preserved non-axial motor function and low affective symptoms). These groups differed in disease duration, axial scores, non-motor burden, and depression, but not in age, sex, or PD subtype.

CONCLUSIONS

High FOF in PD can arise from distinct, relatively "pure" phenotypes-motor-disability, anxiety, or gait impairment. Recognizing these drivers may guide phenotype-specific rehabilitation, such as targeted physiotherapy for gait-dominant cases or psychological interventions for anxiety-driven profiles, potentially improving functional outcomes and QoL.