Flexed Posture in Parkinson Disease: Associations With Nonmotor 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 nonmotor 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. Nonmotor 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 nonmotor impairments and truncal posture, and between truncal posture and activities. Results Greater disease severity, greater 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 30% 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-to-moderate disease severity. Conclusions Spinal proprioception and postural fatigue were the only nonmotor 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 might develop flexed posture.