Brain Changes from Small Vessel Disease Demonstrated by Impaired Gait Speed

Researchers writing in Scientific Reports find that brain changes that occur as a result of small vessel disease, are associated with worse performance in gait speed, the chair-stands test and standing balance in senior patients.

“Our study confirms a negative impact of small vessel disease-related morphologic brain changes on gait speed (in addition to age, sex and hypertension and independent from normalized brain volume). The presence of white matter hyperintensity (WMH) seems to be the major driving force for gait impairment in healthy elderly subjects,” wrote Joanna Wardlaw and colleagues in the January 30 online issue of Scientific Reports.

Also referred to as leukoaraiosis, white matter hyperintensities are a common finding on magnetic resonance images of the brain in senior patients or patients with stroke or dementia. In addition to affecting cognitive impairment, they are associated with higher risk of stroke and dementia.

In this study, Dr. Wardlaw, chair of Applied Neuroimaging at the University of Edinburgh, set out to determine if and how single markers of small vessel disease affected gait and balance in a group of 678 healthy men and women between 71-74 years old. They underwent assessments of comprehensive risk, gait and balance, and brain status through MRIs. Tests included the six-meter walk test and chair-stands and standing balance tests.

Researchers compared the impact of small vessel disease markers (white matter hyperintensity, microbleeds, lacunes, enlarged perivascular spaces and brain atrophy) and on gait performance finding that the matter hyperintensity score or volume were significant and proved to be independent predictors of gait speed in the regression model and similarly, with the global small vessel disease score.

Historical Perspective

Gait and balance impairment in older individuals has a high prevalence and can restrict independence and increase the risk of falls, institutionalization and mortality. Prevalence rises steeply with age, with a rate of about 15 percent at age 60 increasing to more than 50 percent at ages 80 and older. In addition to age, vascular risk factors such as high blood pressure and diabetes contribute to gait and balance disturbances.

Cerebral small vessel disease appears on MRI as white matter hyperintensities (WMH), microbleeds, lacunes and enlarged perivascular spaces. The strength of associations between these aspects of small vessel disease and disturbed gait and balance, however, has remained unclear, leading Dr. Wardlaw  and colleagues to aim at demonstrating links between distinct small vessel disease MRI markers and gait or balance function.

Findings

Reporting associations with small vessel disease and brain volume abnormalities, researchers found that gait speed was significantly slower in subjects with higher white matter hyperintensities (P=0.001) and higher perivascular space scores (P=0.069), higher white matter hyperintensities volume (P=0.001), lower atrophy (P=0.036) and higher global small vessel disease scores (P=0.007).

Regression models showed that gait scores were consistently explained by two single markers of small vessel disease, the white matter hyperintensities score or white matter hyperintensities volume and the global small vessel disease score (R2=1.3-2.3 percent). Chair-stands test results were significantly worse in older individuals, smokers and those with diabetes; females, subjects with high blood pressure or diabetes had significantly worse standing balance. But while chair-stands test regression trended similarly to small vessel disease (R2 = 0.6–0.7 percent), differences did not survive statistical adjustments. Also, standing balance did not correlate with any small vessel disease markers.

Demographics and risk factors such as sex (females worse), age and high blood pressure, generally explained gait independent of brain atrophy status. This, along with the observation of a steep prevalence increase in gait impairment from 60-69 years (11 percent) to 70-79 years (38 percent), implies that controlling for age effects remains crucial for researchers.

Compared to prior studies that included neurologic patients, the small vessel disease contribution to gait changes is quite low in this study. That may be explained, the authors suggest, by the lower small vessel disease burden in this healthy population. Among them, 44.4 percent had only minor individual small vessel disease markers.

When Pinter et al. looked separately at those subjects with moderate to severe small vessel disease scores (global small vessel disease score of at least 2), prediction improved substantially and the small vessel disease and atrophy scores accounted for 6.4 percent and 6 percent, respectively, of the variance. Demographics and risk factors did not add predictive power.

“The presence of white matter hyperintensities seems to be the major driving force for small vessel disease on gait impairment in healthy elderly subjects,” Pinter et al. concluded.

References:

Daniela Pinter, Stuart J. Ritchie, Fergus Doubal, et al. “Impact of small vessel disease in the brain on gait and balance.” Science Reports. Published online Jan. 30, 2017. DOI: 10.1038/srep41637