Flexed Posture in Parkinson Disease: Associations With Non-Motor Impairments and Activity Limitations.

BACKGROUND: People with Parkinson disease (PD) are twice as likely to develop flexed truncal posture as the general older population. Little is known about the mechanisms responsible beyond associations with age, axial motor impairments, and disease severity.

OBJECTIVE: The objective was to explore: (1) the associations of the non-motor impairments of PD with flexed posture and (2) the relationships of flexed posture with activity limitations.

DESIGN: This was a cross-sectional study.

METHODS: Seventy people with PD participated. Posture was measured in standing as the distance between the seventh cervical vertebra and a wall. Non-motor impairments (cognition, depression, pain, fatigue, and proprioception) and activity performance (upper limb activity, bed transfers, respiratory function, and speech volume) were variously assessed using objective measures and self-report questionnaires. Univariate and multivariate regression analyses were performed to ascertain relationships between non-motor impairments and truncal posture, as well as between truncal posture and activities.

RESULTS: Greater disease severity, higher axial impairment, poorer spinal proprioception, greater postural fatigue, and male sex were significantly associated with flexed truncal posture. The multivariate model containing these factors in addition to age explained 31% of the variability in flexed truncal posture, with male sex and axial motor impairment continuing to make independent contributions. A significant association was found between greater flexed truncal posture and poorer upper limb activity performance and respiratory function.

LIMITATIONS: A limitation to this study was that participants had mild-moderate disease severity.

CONCLUSIONS: Spinal proprioception and postural fatigue were the only non-motor impairments to make significant contributions to flexed posture. Given the negative influence of flexed posture on upper limb activity and respiratory function, interventions targeting spinal proprioception and postural awareness should be considered for people with PD who may develop flexed posture.