Psychoacoustic characteristics of tinnitus in temporomandibular disorders: a systematic review.

Loneliness has been defined as distress due to the discrepancy between desired and perceived interpersonal relationships (Cacioppo & Cacioppo, ). It is related to, but distinct from, objective social isolation, which corresponds to the number of people in an individual’s environment. Because loneliness reflects perceived disconnection rather than objective contact, it may persist even when individuals are surrounded by others and may be especially clinically relevant for individuals with mental health conditions like posttraumatic stress disorder (PTSD), where avoidance, mistrust, and emotional numbing can disrupt the capacity to feel socially connected. In 2023, loneliness was identified by the US Surgeon General as an ‘epidemic’ that requires attention and intervention (United States Department of Health and Human Services, ). This conclusion was based on research showing that loneliness is associated with a host of negative physical and mental health outcomes, including but not limited to increased all-cause mortality (Holt-Lunstad et al., ), cardiovascular disease (Teshale et al., ), dementia (Kuiper et al., ), depression (Mann et al., ), and risk of suicide (Teo et al., ), as well as fewer prosocial behaviors and lower social self-efficacy (Palmer et al., ), and poorer academic and work performance (Bowers et al., ; Guay et al., ). Loneliness and these associated negative outcomes are highly prevalent among military veterans (Wilson et al., ). Findings from a nationally representative sample reveal that nearly 40% of veterans report moderate to high levels of loneliness (Ong et al., ), with severity of loneliness associated with increased odds of difficulties with mental health, physical health, and functioning (Schafer et al., ). Also among veterans, being married/partnered and perceiving greater purpose in life were associated with reduced loneliness over time, whereas poorer cognitive functioning, psychological distress (including symptoms of PTSD), and having experienced more childhood adversity predicted greater increases in loneliness (Ong et al., ). Veterans who reported feeling lonely ‘sometimes’ and ‘often’ were 3 and 12 times more likely to endorse suicidal ideation, respectively, compared to veterans who reported ‘hardly ever’ feeling lonely (Straus et al., ). As noted, one of the mental health conditions associated with loneliness is PTSD (Solomon et al., ), which is highly prevalent among veterans (Lehavot et al., ). PTSD is characterized by intrusions of traumatic memories, avoidance of trauma reminders, negative thoughts and feelings, and hyperarousal – all of which could serve to isolate veterans from others. Among those experiencing PTSD symptoms, loneliness may also increase the risk for other difficulties, such as suicidal ideation (Levi-Belz et al., ).