Investigating Biomarkers for Mild Cognitive Impairment

Introduction to Dual-Task Gait Testing

Researchers focusing on biomarkers for mild cognitive impairment (MCI) have identified dual-task gait testing as a promising method to detect patients at heightened risk of dementia. This approach involves individuals walking while simultaneously engaging in a cognitive task, providing insights into their cognitive and motor functions. Early diagnosis of MCI allows for timely intervention, better caregiver guidance, and more accurate prognoses.

Importance of Biomarkers in Differential Diagnosis

Biomarkers play a crucial role in the differential diagnosis of MCI, especially among non-demented individuals. MCI is linked to an increased likelihood of positive Alzheimer’s disease (AD) biomarkers, with an annual conversion rate of 5% to 17% progressing to AD, the most prevalent cause of dementia in older adults. Current therapeutic options yield only modest benefits in cognitive decline, and research indicates that the pathophysiological processes of AD may begin years or even decades before cognitive symptoms manifest.

Challenges in Therapeutic Interventions

The ineffectiveness of existing treatments may stem from the initiation of therapy only after noticeable cognitive impairment has occurred. By this stage, neuronal damage and synaptic dysfunction may be too advanced for successful intervention, highlighting the critical need for earlier detection and treatment.

Identifying At-Risk Patients

To identify individuals at risk of dementia, researchers are exploring subtle cognitive changes and surrogate biomarkers of AD pathology. Large cohort studies have revealed that motor system impairments, particularly slower gait, are observable during the initial stages of both AD-associated and non-AD-associated dementia. This observation is grounded in the understanding that cognition and motor systems share overlapping brain networks, particularly within the temporal and pre-frontal regions.

Research Led by Manuel M. Montero-Odasso

A team led by Manuel M. Montero-Odasso at the Parkwood Institute in London, Canada, investigated whether motor control could serve as a surrogate marker for dementia risk. They hypothesized that individuals progressing to dementia would demonstrate greater gait changes during dual-task performance—a phenomenon known as dual-task gait cost. The study included 112 participants, averaging 76 years of age, with 51% being male, and monitored their gait and dementia progression over six years from 2007 to 2016.

Methodology and Findings

Gait assessment utilized an electronic walkway to measure spatial and temporal parameters, while a neuropsychological test battery was used to characterize MCI and track dementia progression. The findings indicated that dual-task gait testing correlates with dementia progression in older adults with MCI. Participants exhibiting a high dual-task gait cost while performing cognitive tasks, such as counting backward or naming animals, were found to have an elevated risk of developing dementia.

Implications of Gait Control on Cognitive Domains

The study highlighted that the frontal-hippocampal and pre-frontal-striatal circuits, which govern episodic memory and executive function, respectively, also play a role in gait control. These cognitive domains were notably affected in the participants of the study.

Conclusion: A Potential Motor Biomarker

The non-invasive nature of dual-task gait testing makes it a straightforward, cost-effective tool that can be easily implemented in clinical settings. This method offers a valuable screening option for identifying patients who may benefit from early interventions, positioning it as a potential motor biomarker for dementia progression.

Author Information

Written By: Joseph M. Antony, PhD