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.

Brain-derived neurotrophic factor (BDNF) is a nerve growth factor that has antidepressant-like effects in animals and may be implicated in the etiology of mood-related phenotypes. However, genetic association studies of the BDNF Val66Met polymorphism (single nucleotide polymorphism rs6265) in major depressive disorder (MDD) have produced inconsistent results. We conducted a meta-analysis of studies comparing the frequency of the BDNF Val66Met-coding variant in depressed cases (MDD) and nondepressed controls. A total of 14 studies involving 2812 cases with DSM-III or -IV defined MDD and 10 843 nondepressed controls met the inclusion criteria. Analyses were stratified either by gender or ethnicity (Asian and Caucasian) because MDD is more prevalent in women and in Caucasians and because BDNF allele frequencies differ by ethnicity. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were provided for allelic analyses (Met versus Val), as well as for genotypic analyses (Met/Met and Val/Met versus Val/Val). In the total sample, the BDNF Val66Met polymorphism was not significantly associated with depression. However, the gender stratified analyses revealed significant effects in both the allelic and genotypic analyses in men (OR MET , 95% CI; 1.27 (1.10-1.47); OR MET/MET , 95% CI; 1.67 (1.19-2.36)). Stratification according to ethnicity did not show significant effects of the Val66Met polymorphism on MDD. Our results suggest that the BDNF Val66Met polymorphism is of greater importance in the development of MDD in men than in women. Future research into gender issues will be of interest.

Many longitudinal studies have investigated whether self‐esteem predicts depressive symptoms (vulnerability model) or the other way around (scar model) in adolescents. The most common method of analysis has been the cross‐lagged panel model (CLPM). The CLPM does not separate between‐person effects from within‐person effects, making it unclear whether the results from previous studies actually reflect the within‐person effects or whether they reflect differences between people. We investigated the associations between self‐esteem and depressive symptoms at the within‐person level, using random intercept cross‐lagged panel models (RI‐CLPMs). To get an impression of the magnitude of possible differences between the RI‐CLPM and the CLPM, we compared the results of both models. We used data from three longitudinal adolescent samples (age range: 7–18 years; study 1: N = 1948; study 2: N = 1455; study 3: N = 316). Intervals between the measurements were 1–1.5 years. Single‐paper meta‐analyses showed support for small within‐person associations from self‐esteem to depressive symptoms, but not the other way around, thus only providing some support for the vulnerability model. The cross‐lagged associations in the aggregated RI‐CLPM and CLPM showed similar effect sizes. Overall, our results show that over 1‐ to 1.5‐year time intervals, low self‐esteem may negatively influence depressive symptoms over time within adolescents, but only weakly so. © 2018 The Authors. European Journal of Personality published by John Wiley & Sons Ltd on behalf of European Association of Personality Psychology

Friendship quantity and quality are related to adolescent loneliness, but the exact link between these constructs is not well understood. The present study aimed to examine whether adolescents' perception of friendship quantity and quality, and the perceptions of their peers, were related to loneliness. We examined the relation between loneliness and the number of unilateral and reciprocal friendships and compared the views of best friendship quality. Overall, 1,172 Dutch adolescents (49.1% male, M age = 12.81, SD = .43) nominated their friends and rated their friendship quality. Friendship quantity was measured using sociometrics to distinguish reciprocated and unilateral (i.e., one-sided) friendships. The analyses indicated that loneliness was related to fewer reciprocal and unilateral-received friendships (i.e., the adolescent received a friendship nomination but did not reciprocate that nomination) and a lower quality of best friendship. Actor-partner interdependence analyses revealed that adolescents' loneliness was related to a less positive evaluation of their friendship, as reported by adolescents themselves (i.e., a significant actor effect) but not by their friends (i.e., nonsignificant partner effect). These findings (a) indicate that loneliness is negatively related to the number of friends adolescents have, as perceived by themselves and their peers and (b) suggest that, once a friendship is established, lonely adolescents may interpret the friendship quality less positively compared to their friends. Implications of these findings for our current understanding of adolescent loneliness are discussed, and suggestions for future research are outlined.

The relation between attachment representations and personality disorders was examined in a sample of 40 Dutch men held in a forensic psychiatric hospital for the commission of serious crimes. Secure attachment representations were virtually absent in the sample; separation from attachment figures in childhood was related to current insecure attachment as well as to personality disorders. Use of attachment theory in research and clinical work with criminals is discussed.