In double limb stance, three levels of postural difficulty were studies on a force platform (rigid surface with eyes open, rigid surface with eyes closed, and foam surface with eyes closed).
Clinical features of RTT include autistic features, mental retardation, postural hypotonia, difficulties in locomotion, loss of purposeful hand use, stereotyped hand movements, progressive scoliosis, seizures, and autonomic nervous system disturbances (2– 4).
Different variables related to the greater risk of falls have also been reported such as factors of the individuals themselves (muscular strength of the lower extremities, equilibrium or postural competence, difficulties in vision, cognitive deterioration), purely environmental factors (home lighting, rugs, pets...) and iatrogenic factors (different groups of drugs, drug combinations) [ 18- 21].
In a dual-task condition, an increased RT can thus be considered as a marker of an increased postural task difficulty [14], [15], [19].
All cases exhibited a variable combination of asymmetrical bradykinesia, rigidity, rest and postural tremor, walking difficulties, postural instability and excellent response to dopaminergic treatment, consistent with a clinical diagnosis of Parkinson's disease.
Like older adults, people with brain injury or stroke show difficulties with postural balance, exhibit gait insecurities when performing dual-tasks and have cognitive deficits evident in working memory, attention, and information-processing [ 35, 38].
Although oral medications are known to improve many of the motor and non-motor symptoms associated with PD, late-stage symptoms such as gait difficulties and postural instability are not always responsive to this therapeutic intervention.
64 As postural instability and gait difficulties contribute significantly to the high risk of falls in patients with PD, there is a strong need for further research examining additional non-invasive interventions that target the improvement of segmental control and postural alignment in this population.
In another study, the abundance of Enterobacteriaceae was positively correlated with the severity of PD regarding gait difficulty and postural instability (Scheperjans et al., 2015).
However, when the difficulty of postural task increases in dynamic conditions, the contribution of visual information increases [ 5].
