Caregivers' burden and psychiatric morbidity among informal caregivers of older adults: results from a national survey.

Psychotic-like experiences (PLEs) are subclinical manifestations of psychotic phenomena, such as hallucination-like perceptual abnormalities, delusion-like beliefs, and suspicious or unusual thought content, that occur in individuals without a diagnosed psychotic disorder []. These experiences are typically less frequent, less severe, and less persistent than clinical psychotic symptoms and are conceptualized within a psychosis continuum framework, ranging from transient subclinical experiences to persistent and severe psychotic disorders []. Epidemiological studies indicate that PLEs are relatively common in the general population, with lifetime prevalence estimates of approximately 5.8% []. Accumulating evidence further suggests that PLEs are associated with adverse mental and physical health outcomes [, ], as well as impaired social functioning [], highlighting their clinical and public health relevance even in the absence of a diagnosable psychotic disorder. There is growing evidence that PLEs are closely linked to social experiences, particularly loneliness []. Population-based studies have consistently shown that individuals reporting PLEs experience higher levels of loneliness compared with those without such experiences [, ], and recent meta-analytic findings demonstrate a robust association between psychotic experiences—especially paranoia-related symptoms—and loneliness []. Although these findings support a strong association, the causal direction between loneliness and PLEs remains to be clarified. Nonetheless, several theoretical frameworks posit that loneliness may play a role in the development and maintenance of PLEs, potentially through mechanisms such as heightened social threat perception, negative social cognition, and emotional distress [, ]. Importantly, loneliness is conceptually and empirically distinct from social isolation []. Loneliness refers to the subjective perception of a discrepancy between desired and actual social relationships, whereas social isolation reflects an objective lack or paucity of social contacts and social participation. Although loneliness and social isolation are moderately correlated and often co-occur, they represent separable constructs [, ]. Individuals may feel lonely despite having frequent social interactions, or conversely may not feel lonely despite being socially isolated. This yields four social profiles defined by the presence or absence of loneliness and social isolation, which may have different implications for PLEs. Emerging evidence suggests that PLEs may be more strongly associated with subjective loneliness than with objective social isolation [, ], underscoring the importance of considering both constructs simultaneously. Nevertheless, few studies have explicitly examined how different combinations of loneliness and social isolation relate to PLEs, leaving an important gap in understanding the social context in which PLEs arise. Among individuals experiencing loneliness, social interactions may not necessarily function as protective but may instead be perceived as socially threatening or distressing, possibly due to heightened vigilance to social threat and negative cognitive biases in social information processing [, ]