Long Loop Reflex 2 in Patients with Cortical Dementias: A Pilot Study

Area of Science:

• Neuroscience
• Neurology
• Biomarker Research

Background:

• Dementia represents a growing global health crisis, with increasing prevalence, particularly in developing nations.
• Early diagnosis is crucial for effective disease-modifying treatments, but current tools struggle to differentiate dementia types in early stages.
• There is a need for accessible and inexpensive biomarkers to improve early diagnostic sensitivity.

Purpose of the Study:

• To investigate if long loop reflex (LLR2) is differentially affected in early-stage Alzheimer's dementia (AD) and frontotemporal dementia (FTD).
• To explore the potential of LLR2 as an early diagnostic biomarker for distinguishing between AD and FTD.

Main Methods:

• Mild, clinically probable cases of AD and FTD were included based on established criteria.
• Long loop reflex (LLR) testing was performed on the upper limb via median nerve stimulation.
• Assessment included the presence/absence of LLR2, as well as latency, amplitude, and duration measurements.

Main Results:

• Long loop reflex (LLR2) showed differential effects in AD and FTD.
• Absence of LLR2 was consistently observed in patients with FTD.
• This finding is hypothesized to relate to the early breakdown of frontal subcortical circuits in FTD.

Conclusions:

• LLR2 is differentially affected in FTD and AD.
• The consistent absence of LLR2 in FTD suggests its utility as a biomarker.
• LLR2 may serve as a cost-effective and early biomarker for differentiating between these two prevalent forms of cortical dementia.