Age-related decline of neuroplasticity to intermittent theta burst stimulation of the lateral prefrontal cortex and its relationship with late-life memory performance

Abstract

OBJECTIVE: Advanced age is accompanied by a deterioration in memory performance that can profoundly influence activities of daily living. However, the neural processes responsible for age-related memory decline are not fully understood. Here, we used transcranial magnetic stimulation (TMS) in combination with electroencephalography (EEG) to assess age-related changes in neuroplasticity in the human prefrontal cortex. METHODS: TMS-evoked cortical potentials (TEPs) were recorded before and following the neuroplasticity-inducing intermittent theta burst stimulation (iTBS), applied to the left lateral prefrontal cortex in healthy young (n = 33, mean age 22 ± 3 years) and older adults (n = 33, mean age 68 ± 7 years). RESULTS: iTBS increased the amplitude of the positive TEP component at 60 ms after the TMS pulse (P60) in young, but not older adults. This age-related decline in P60 plasticity response was associated with poorer visuospatial associative (but not working) memory performance in older adults. CONCLUSIONS: These findings suggest that neuroplasticity in the human lateral prefrontal cortex is reduced in older relative to young adults, and this may be an important factor in age-related memory decline. SIGNIFICANCE: This may have important implications for the early detection of cognitive decline and dementia.