Aging's Effect on Mobility May Lie in the White Matter

By Crystal Phend
MANNHEIM, Germany, March 17 -- Falls and mobility problems in older age may reflect not only worsening balance but also changes in the white matter of the brain, researchers found.Gait and balance problems as well as slower walking speed among older adults were linked to increasing severity of white matter lesions as seen on MRI, reported Hansjoerg Baezner, M.D., Ph.D., of Mannheim University Hospital and the University of Heidelberg here, in the March 18 issue of Neurology.These prospective findings have implications for practice, commented Timothy C. Hain, M.D., of Northwestern University in Chicago, in an interview."If your patient has a large number of white matter lesions, you should be very concerned about their balance and risk for falling," he said. These patients can be encouraged to take measures to prevent injury such as installing bars in the bathroom and use of a cane, he added.
"Physical activity might have the potential to reduce the risk of limitations in mobility," Dr. Baezner and colleagues wrote.
Cerebral white matter changes - leukoaraiosis -- are common in the elderly, but also occur in patients with migraine and diseases such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.
The main cause of age-related white matter changes appears to be vascular problems, such as high blood pressure, Dr. Hain said.
The researchers analyzed the relation of these changes to gait and balance in the prospective Leukoaraiosis and Disability (LADIS) Study. This study included 639 men and women ages 65 to 84 who had brain scans and walking and balance tests at 11 European centers.
All patients displayed some degree of age-relate white matter changes on MRI, but none of the patients was disabled. Patients were referred to the study for cognitive symptoms (26.3%), minor stroke (19.1%), motor symptoms (4.4%), psychiatric symptoms (2.0%), and other neurologic disturbances (20.2%).
Over three years of follow-up, motor function as measured on the Short Physical Performance Battery was worse for patients with more severe age-related white matter changes. Mean scores were 10.2 for mild changes, 9.9 for moderate changes, and 8.9 for severe changes (P<0.001).
Patients with "pathologic" motor performance scores of 10 and below were more likely to have severe age-related white matter changes than mild changes even on multivariate analysis (odds ratio 2.29, 95% confidence interval 1.42 to 3.50).
For balance, patients were able to hold a single leg stance for less time the greater their age-related white matter changes (mean 18.9 seconds for mild, 16.4 for moderate, and 13.6 for severe changes, P<0.001).
Patients with "pathologic" balance, defined as a single leg stance time of less than 15 seconds, were significantly more likely to have severe than mild age-related white matter changes even after multivariate adjustment (OR 2.05, 95% CI 1.30 to 3.25).
Likewise, walking speed was significantly reduced among patients with greater white matter changes (mean 1.24 m/second for mild, 1.18 for moderate, and 1.09 for severe changes, P<0.001).
"Pathologic" walking speeds of less than 1.2 m/second were significantly more likely with severe than mild age-related white matter changes as well in multivariate analysis (OR 1.72, 95% CI 1.11 to 2.66).
Regular physical activity was associated with better motor performance (OR 0.44, 95% CI 0.29 to 0.66) and better balance (OR 0.45, 95% CI 0.30 to 0.68) but not walking speed.
However, the interaction between physical activity and age-related white matter changes was not significant, "indicating that physical activity did not modulate the association between age-related white matter change severity and deficiencies in gait and balance," the researchers said.
The effect remained significant even after adjustment for history of gait disturbance or falls.
"This is a new message because, so far, several small studies have shown a positive effect of physical exercise on selected aspects of mobility in the elderly," they said, "but there still has been contradictory evidence regarding its influence on gait, balance, and activities of daily living."
Dr. Baezner's group is now analyzing the longitudinal study to see whether exercise delays disability.
The study was limited by its non-population-based design. But because their reasons for referral were those commonly leading to discovery of white matter changes in older adults, it reflected the patient population likely to be encountered in clinical practice, they said.
The study was supported by the European Union within the Fifth European framework Program "Quality of Life and Management of Living Resources." The researchers reported no conflicts of interest.
Primary source: NeurologySource reference:Baezner H, et al "Association of gait and balance disorders with age-related white matter changes: The LADIS Study" Neurology 2008; 70: 935-942.