Discussion
obesity, vestibular disease, cerebral hypoperfusion, stroke, IADL disability, impaired functional status, ADL disability, visual impairment, PD, dizziness, mild/moderate alcohol, status disability, vestibular dysfunction, increase orthostatic intolerance, disability, ADL/IADL disability
OBESITY, STROKE, CHRONIC DISEASES, MULTIPLE SYSTEM ATROPHY, VESTIBULAR DISEASE, NEURODEGENERATIVE DISORDER
To the best of our knowledge, there have been no studies investigating the relationships among PD, PH, and ADLs/IADLs concomitantly in an older population. In this large transversal study, the association of ADL and IADL disability with PD and PH in both older genders was controlling many confounding factors, including age, important chronic diseases, lifestyle habits, and medication use. The findings of this study indicated that impaired functional status, manifested by ADL or IADL disability, was positively associated with PD, but not PH in total subjects. The older adults with either ADL or IADL disability may be more likely to have PD. When considering gender differences, ADL and IADL disability were also positively associated with PD in older men. In older women, ADL disability was positively associated with PD, although ADL disability was not in multivariate analysis. In Ensrud KE et al.’s study, PD was associated with IADL disability in older women after adjusting age [An explanation for the positive link between functional disabilities and PD has not been made clear. ADL/IADL disability and PD may have reciprocal associations because limited activity resulting from ADL/IADL disability may increase orthostatic intolerance due to extensive venous pooling related to less action of the leg skeletal muscle pump [Some factors associated with PD include PH, cerebral hypoperfusion, vestibular dysfunction, visual impairment, and disorders of the proprioceptive system [Older women were more likely to have PD, which concurred with the findings of a previous study [Impairments in the heart rate response, stroke volume, and vascular resistance during postural changes may lead to PH [This study had some limitations. First, a causal relationship between functional status disability and PD cannot be established because this study was cross-sectional. Second, the diagnosis of dizziness was from a subjective self-report after a postural change. Thus, chronic repeated episodes, the frequency, duration and severity of dizziness could not be measured. However, we measured PD and PH simultaneously when the subjects actively stood up, which potentially presented a more accurate relationship between PH and PD. Third, although we adjusted age, obesity, many chronic diseases, smoking, mild/moderate alcohol consumption, regular exercise, and medication use to reduce the degree of bias, the influences of vestibular disease and rare neurodegenerative disorder, such as multiple system atrophy, which were not collected in this study, cannot be completely ruled out. We also noted ADL/IADL were associated with increased ORs of PD/PH, which was independent of the selected potential confounders. These potential confounders are potential associated factors for PD/PH and are also considered to have associations with ADL/IADL. Fourth, the subjects were confined to a Taiwanese population, so more studies should be conducted in other ethnic groups.