Most people have experienced loneliness and have been able to overcome it to reconnect with other people. In the current review, we provide a life-span perspective on one component of the evolutionary theory of loneliness—a component we refer to as the reaffiliation motive (RAM). The RAM represents the motivation to reconnect with others that is triggered by perceived social isolation. Loneliness is often a transient experience because the RAM leads to reconnection, but sometimes this motivation can fail, leading to prolonged loneliness. We review evidence of how aspects of the RAM change across development and how these aspects can fail for different reasons across the life span. We conclude with a discussion of age-appropriate interventions that may help to alleviate prolonged loneliness.

The present study employed latent growth mixture modeling to discern distinct trajectories of loneliness using data collected at 2‐year intervals from age 7–17 years (N = 586) and examine whether measures taken at age 5 years were good predictors of group membership. Four loneliness trajectory classes were identified: (1) low stable (37% of the sample), (2) moderate decliners (23%), (3) moderate increasers (18%), and (4) relatively high stable (22%). Predictors at age 5 years for the high stable trajectory were low trust beliefs, low trusting, low peer acceptance, parent reported negative reactivity, an internalizing attribution style, low self‐worth, and passivity during observed play. The model also included outcome variables. We found that both the high stable and moderate increasing trajectories were associated with depressive symptoms, a higher frequency of visits to the doctor, and lower perceived general health at age 17. We discuss implications of findings for future empirical work.

Different theoretical contentions on gender differences in loneliness exist, often including the emergence of gender differences in particular developmental periods. To explain those ideas, the current meta–analysis synthesizes the available evidence on gender differences in loneliness across the lifespan. Three–level meta–analyses were conducted with 751 effect sizes, covering 399,798 individuals (45.56% males). Results showed a close–to–zero overall effect ( g = 0.07). Most examined moderators were non–significant, except for age, the scope of the sampling area, and year of publication. Most importantly, all effects were small, suggesting that across the lifespan mean levels of loneliness are similar for males and females.

Based on current theories of depression, reciprocal links between loneliness and depressive symptoms are expected to occur. However, longitudinal studies on adolescent samples are scarce and have yielded conflicting results. The present five-wave longitudinal study from mid- to late adolescence (N=428, M age at T1=15.22 years; 47% female) examined the direction of effect between loneliness and depressive symptoms, using cross-lagged path analysis. In addition, the robustness of these prospective associations was tested by examining the role of the Big Five personality traits (i.e., extraversion, conscientiousness, agreeableness, neuroticism, and openness) as explaining factors and moderators. Results indicated that loneliness and depressive symptoms influenced one another reciprocally, and these reciprocal associations were not attributable to their mutual overlap with personality traits. In addition, neuroticism was found to be a moderator, in that the bidirectional effects between loneliness and depressive symptoms were only found in adolescents high in neuroticism. Practical implications are discussed, and suggestions for future research are outlined.