Silence, Solitude, and Serotonin: Neural Mechanisms Linking Hearing Loss and Social Isolation

Abstract

For social animals that communicate acoustically, hearing loss and social isolation are factors that independently influence social behavior. In human subjects, hearing loss may also contribute to objective and subjective measures of social isolation. Although the behavioral relationship between hearing loss and social isolation is evident, there is little understanding of their interdependence at the level of neural systems. Separate lines of research have shown that social isolation and hearing loss independently target the serotonergic system in the rodent brain. These two factors affect both presynaptic and postsynaptic measures of serotonergic anatomy and function, highlighting the sensitivity of serotonergic pathways to both types of insult. The effects of deficits in both acoustic and social inputs are seen not only within the auditory system, but also in other brain regions, suggesting relatively extensive effects of these deficits on serotonergic regulatory systems. Serotonin plays a much-studied role in depression and anxiety, and may also influence several aspects of auditory cognition, including auditory attention and understanding speech in challenging listening conditions. These commonalities suggest that serotonergic pathways are worthy of further exploration as potential intervening mechanisms between the related conditions of hearing loss and social isolation, and the affective and cognitive dysfunctions that follow.

Neurophysiological investigation of auditory intensity dependence in patients with Parkinson’s disease

“…Although no evidence was found for differences in the early components of auditory input processing between patients with PD and HCs in the present study, early stage input alterations in PD have been suggested based on other methodological approaches (De Groote et al 2020). Therefore, an increased allocation of attention could also be interpreted as a compensatory mechanism for changes along the auditory pathway inducing a PD-specific approach of auditory input processing (Alain et al 2004;Boecker et al 1999;Getzmann et al 2014;Keesom and Hurley 2020).…”

“…As in the present study IDAEP was investigated in patients with PD, the current discussion specifically focused on the involvement of serotonin and its relationship with dopaminergic neurotransmission in auditory processing in PD. Nonetheless, other neurotransmitter systems and various interactions could also be involved (Keesom and Hurley 2020). More specifically, dopamine, glutamate, gamma-aminobutyric acid, and acetylcholine are common neurotransmitters of the auditory system and BG circuitry (Jafari et al 2020;Lee and Godfrey 2014;Oestreicher et al 2002;Ruel et al 2007).…”

“…More specifically, dopamine, glutamate, gamma-aminobutyric acid, and acetylcholine are common neurotransmitters of the auditory system and BG circuitry (Jafari et al 2020;Lee and Godfrey 2014;Oestreicher et al 2002;Ruel et al 2007). In this way, possible neurophysiological interaction mechanisms between peripheral and central auditory processing, and non-auditory systems must be considered in PD (Keesom and Hurley 2020). Finally, dopamine and dopaminergic medication exert their influence on the various neurotransmitters and their interactions involved (Jafari et al 2020), making understanding of the neurophysiological mechanisms of auditory input processing in PD challenging.…”

Understanding Vulnerability to Late-Life Suicide

“…Increasing the availability of virtual mental health and substance use treatment is a strategy to increase access. Especially beneficial to elderly patients with mobility problems, home-based tele-treatment has been shown to be feasible and well accepted in the areas of inpatient and nursing home consultation, cognitive testing, dementia diagnosis and treatment, depression in integrated and collaborative care models, and psychotherapy [ 35 , 39 , 43 , 50 , 51 ]. The PROSPECT and IMPACT studies demonstrated that a greater percentage of depressed patients receiving collaborative care (medication, psychotherapy or both) experienced a decline in suicidal ideation than depressed patients receiving routine care.…”

Central Auditory Plasticity from Molecules to Behavior

“…Although the behavioral relationship between hearing loss and social isolation is evident, there is little understanding of their interdependence at the level of neural systems. Keesom and Hurley [ 9 ] review the interactions of the serotonergic pathways within the auditory system as well as within other brain regions. Such interactions are difficult to tease apart, but they start providing strong evidence to further explore the serotonergic pathways as potential intervening mechanisms between the related conditions of hearing loss and social isolation, and the affective and cognitive dysfunctions that follow psychiatric disorders.…”