APA Dictionary of Psychology

impairment in the ability to maintain balance. A defining feature of Parkinson’s disease, usually appearing in its middle stages, postural instability is associated with significantly decreased quality of life due to unsteady mobility and with a heightened risk of mortality because of falls. Balance training and other forms of physical therapy can help to reduce postural instability, but their success may be limited over the long term. Research suggests that patients who also have diabetes mellitus, cognitive impairment, or depression are at increased risk for postural instability; treatment of these conditions may limit or improve the instability.