Age-related changes in prepulse inhibition of the startle response

Abstract

IntroductionAcoustic prepulse inhibition of the startle response (PPI) is a phenomenon characterized by the reduction in the startle reflex caused by the presence of weak and brief stimulus before an intense and sudden stimulus (pulse). These phenomena can be observed in several species, but in humans it is commonly measured by the eyeblink using electromyography. PPI works as an operational measure of sensorimotor gating, which is the ability to suppress motor responses for sensory stimulus. Healthy aging is marked by several changes in neural processing, like inhibitory functioning decline. In this line, PPI measure can be a potential biomarker for changes related to the aging process.MethodsIn this research we aim to investigate if PPI is reduced with aging and if this reduction would be associated with cognitive functioning of older adults. To this aim, we compared PPI levels of older adults (over 60 years old) with PPI levels of young adults (from 18 to 28 years old).ResultsWith that, we found, significantly lower PPI level (F[1,25] = 7.44 p = 0.01) and lower startle amplitude startle amplitude: (U = 26.000 p = 0.001) in older adults than in young adults. However, we did not find differences in levels of habituation (T = −1.1 p = 0.28) and correlation between PPI and cognition within the sample of healthy older adults.DiscussionOur results demonstrate that aging is a factor that affects PPI and that it does not seem to predict cognition, however, future studies should explore the potential of using PPI for monitoring cognitive changes associated with techniques such as cognitive training.

Age and sex effects on paired-pulse suppression and prepulse inhibition of auditory evoked potentials

“…The PPI of the acoustic startle reflex and the current PPI have similar age and sex biases, but different age and sex effects on the test response: the elderly showed a weaker acoustic startle reflex in previous studies (Ellwanger et al, 2003;de Oliveira et al, 2023), but not in the present study (Figure 3C), and females showed stronger test alone responses in this study, but not for the acoustic startle reflex (Kumari et al, 2004). The most important methodological difference may be that the acoustic startle reflex was the peripheral response in previous studies and the brain response in the present study.…”

“…A recent study using the trigeminal blink reflex showed that PPI of the early component of the blink reflex occurred in the first stage of brain processing in the principal nucleus of the trigeminal nerve and did not involve higher complex processes ( Inui et al, 2023 ). In studies with PPI of the acoustic startle reflex, one reported decreased inhibition in older subjects ( de Oliveira et al, 2023 ), while others reported no effect of age ( Filion and Poje, 2003 ; Scholes and Martin-Iverson, 2009 ) or an inverted U-shaped relationship between age and PPI, with the strongest inhibition in middle age ( Ellwanger et al, 2003 ). PPI of the trigeminal blink reflex by somatosensory inputs showed no age effect ( Kofler et al, 2013 ).…”

“…One of the issues associated with interpreting PPI and PPS data is that they are affected by age and sex, similar to many other indexes. Previous studies using P50 gating and PPI of the startle reflex revealed significant sex and age effects (Swerdlow et al, 1993;Kumari et al, 2003;Fuerst et al, 2007;de Oliveira et al, 2023). Accumulating evidence has shown that age and sex widely affect brain function, and these variables may have an impact on the findings or even conclusion of a study (Cahill, 2012).…”