Peripheral nerve conduction study in early cognitive impairment of Alzheimer's disease

Abstract

AbstractBackgroundMild cognitive impairment (MCI) individuals are at a higher risk to develop dementia, especially due to Alzheimer’s disease (AD). Dyskinesia, such as facial expressions, gait and postural changes, retardation and tremor, occurs even before significant clinical symptoms of AD. Besides, elders with central nervous degenerative diseases are more likely to have peripheral neuropathy. However, few studies have been devoted to exploring the relationship between peripheral nerve function and early cognitive impairment. The aim of this study was to compare MCI individuals with the normal population for peripheral nerve conduction, and to assess its relationship with cognitive function in elderly population living in Shanghai.Method74 MCI and 82 healthy controls (HC) underwent a peripheral nerve conduction examination and a neuropsychological evaluation. In order to minimized the effect of somatic diseases on peripheral nerve function, all the participants had no diabetes, thyroid dysfunction, Parkinson's disease and peripheral neuropathy. Nicolet EDX was used to assess peripheral nerve conduction of upper and lower limb, including median and sural sensory and median and peroneal motor nerve action potential amplitudes and velocities. Then we compared the peripheral nerve conduction results between two different cognitive groups. Furthermore, we also investigated the relationship between the peripheral nerve conduction and cognitive function.ResultBetween the two groups, MCI was older than HC (70.36±7.38 vs 68.04±6.27, p=0.07) although there was no significant difference. MCI group had less years of education (10.05±3.58 vs 11.45±2.57, p=0.009) and more depressive symptoms (3.65±4.37 vs 2.70±4.17, p=0.044), but no difference was found in gender. Median and peroneal motor nerve velocities were found slower in MCI group compared to HC group (54.51±4.18 vs 47.13±5.90, p=0.011; 56.36±4.72 vs 49.29±5.65, p=0.023). Both median (p=0.005) and peroneal (p=0.003) motor nerve velocities were correlated with MoCA. Furthermore, linear regression revealed that, after taking age, gender, education, depression and body mass index (BMI) into account as covariates, median motor nerve velocity was associated with MoCA (p=0.019).ConclusionOur study found that peripheral motor nerve velocity may be correlated with early cognitive impairment of AD, suggesting a new, possible research direction of early identification markers for AD.