In Reply We are pleased that our study stimulated discussion about the use of dual-task gait (DTG) as a motor biomarker in mild cognitive impairment (MCI) for dementia risk stratification.
We agree with Ikram and colleagues that DTG as a “brain stress test” can be valuable for dementia prediction among cognitively normal populations. Because stress tests in medicine are generally better suited for asymptomatic populations, there is a biological plausibility that DTG may also detect individuals who are at dementia risk in covert stages.1 Prospective studies of more cognitively heterogeneous cohorts are essential. In the Canadian Consortium on Neurodegeneration in Aging cohort, we are currently measuring DTG in 300 participants with subjective cognitive impairment to assess its predictive ability in a less cognitively impaired population. It is conceivable that DTG may show different results in pre-Alzheimer disease, pre-Lewy body dementia, and prevascular dementia because accumulating knowledge indicates that DTG costs can be a marker of pathogenic processes. Associations between higher DTG costs and β-amyloid brain load levels in cognitively normal samples, and apolipoprotein E4 genotyping in MCI samples, suggest that DTG performance may reflect pathological burdens in brain regions that are shared by cognitive and motor control networks before the onset of overt clinical disease.2,3
Montero-Odasso M, Camicioli R, Muir-Hunter SW. Dual-Task Gait And Incident Dementia—A Step Forward, But Not There Yet—Reply. JAMA Neurol. 2017;74(11):1380–1381. doi:10.1001/jamaneurol.2017.2880
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