Age-related differences in long-term potentiation-like plasticity and short-latency afferent inhibition and their association with cognitive function

Qian Lu; Sisi Huang; Tianjiao Zhang; Jie Song; Manyu Dong; Yilun Qian; Jing Teng; Tong Wang; Chuan He; Ying Shen

doi:10.1136/gpsych-2023-101181

Age-related differences in long-term potentiation-like plasticity and short-latency afferent inhibition and their association with cognitive function

Gen Psychiatr. 2024 Feb 21;37(1):e101181. doi: 10.1136/gpsych-2023-101181. eCollection 2024.

Authors

Qian Lu^#^{1

2}, Sisi Huang^#², Tianjiao Zhang^#², Jie Song^#², Manyu Dong², Yilun Qian², Jing Teng², Tong Wang², Chuan He¹, Ying Shen²

Affiliations

¹ Department of Rehabilitation Medicine, The Affiliated Jiangsu Shengze Hospital of Nanjing Medical University, Suzhou, China.
² Rehabilitation Medicine Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.

^# Contributed equally.

Abstract

Background: The neurophysiological differences in cortical plasticity and cholinergic system function due to ageing and their correlation with cognitive function remain poorly understood.

Aims: To reveal the differences in long-term potentiation (LTP)-like plasticity and short-latency afferent inhibition (SAI) between older and younger individuals, alongside their correlation with cognitive function using transcranial magnetic stimulation (TMS).

Methods: The cross-sectional study involved 31 younger adults aged 18-30 and 46 older adults aged 60-80. All participants underwent comprehensive cognitive assessments and a neurophysiological evaluation based on TMS. Cognitive function assessments included evaluations of global cognitive function, language, memory and executive function. The neurophysiological assessment included LTP-like plasticity and SAI.

Results: The findings of this study revealed a decline in LTP among the older adults compared with the younger adults (wald χ²=3.98, p=0.046). Subgroup analysis further demonstrated a significant reduction in SAI level among individuals aged 70-80 years in comparison to both the younger adults (SAI(N20): (t=-3.37, p=0.018); SAI(N20+4): (t=-3.13, p=0.038)) and those aged 60-70 (SAI(N20): (t=-3.26, p=0.025); SAI(N20+4): (t=-3.69, p=0.006)). Conversely, there was no notable difference in SAI level between those aged 60-70 years and the younger group. Furthermore, after employing the Bonferroni correction, the correlation analysis revealed that only the positive correlation between LTP-like plasticity and language function (r=0.61, p<0.001) in the younger group remained statistically significant.

Conclusions: During the normal ageing process, a decline in synaptic plasticity may precede cholinergic system dysfunction. In individuals over 60 years of age, there is a reduction in LTP-like plasticity, while a decline in cholinergic system function is observed in those over 70. Thus, the cholinergic system may play a vital role in preventing cognitive decline during normal ageing. In younger individuals, LTP-like plasticity might represent a potential neurophysiological marker for language function.

Keywords: Cognitive Neuroscience; Cross-Sectional Studies; Geriatric Assessment; Motor Cortex; Nervous System.