Rizwan Kalani, MD

Tabara Y, Okada Y, Ohara M, Uetani E, Kido T, Ochi N, et al. Association of Postural Instability With Asymptomatic Cerebrovascular Damage and Cognitive Decline: The Japan Shimanami Health Promoting Program Study. Stroke. 2014

Cerebral small vessel disease (cSVD) – lacunar infarcts (LI), periventricular hyperintensities (PVH), and microbleeds (MB) on brain magnetic resonance imaging (MRI) – has been associated with older age, hypertension and reduced physical activity. In this study, Tabara et al evaluated for a potential link between postural instability and asymptomatic cSVD in a middle-aged and older cohort.

Data originated from the Japan Shimanami Health Promoting Program (JSHIPP), a medical evaluation program that assessed age-related pathologies, at Ehime University Hospital over a 7 year period. 1387 healthy individuals with no history of symptomatic stroke or dementia that completed optional brain MRI were incorporated in this study. Postural instability was measured by one-leg standing time (OLST), time until raised leg was put down measured twice (with a maximum of 60 seconds), and posturography. Standard MRI definitions for LI and MB were used; PVH was classified into 5 grades (based on Japan Brain Dock Society guideline) with grade 2 or higher considered pathologic. Cognitive impairment was assessed using a computerized dementia assessment scale (DAS) (which tested immediate and short-term memory, temporal orientation, and visual-spatial perception). Carotid intima-media thickness (CIMT) (evaluated by ultrasonography) was used as a measure of arteriosclerosis.

As expected, subjects with cSVD were older, more often hypertensive, and had higher CIMT. The novel finding was that the frequency of short OLST (especially <20 sec) increased linearly with number of LI (p<0.001), number of MB (p=0.023), and PVH grade (p<0.001). After adjusting for covariates (age, sex, BMI, smoking, hypertension, diabetes, CIMT), the association with LI and MB remained significant. Short OLST was also independently associated with lower DAS (p<0.001).

This is the first report of an independent association of OLST with LI and MB as well as with impaired cognitive function. Interestingly, the association between short OLST and cognitive decline was independent of cSVD. Observational design, lack of functional measures, and brief cognitive testing are notable limitations to this study. Nevertheless, it does warrant further research on the clinical implications and prognostic significance of postural instability as well as better understanding of its relationship with asymptomatic cerebrovascular pathology and cognition.