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A recent meta-analysis revealed that cardiac vagal activity (mostly indicated by vagally-mediated heart rate variability; HRV) decreases significantly from the follicular to luteal menstrual cycle phase in naturally-cycling participants. However, the question remains as to whether cyclical changes in estradiol (E2), progesterone (P4), or both are responsible for HRV fluctuations. We present the first studies to use repeated measures of E2, P4, and HRV across the cycle to model both the unique and interactive effects of person-centered E2 and P4 on HRV in multilevel models. In study one, 40 naturally-cycling participants were assessed weekly across four weeks, and were blind to the cycle focus of the study. In study two, 50 naturally-cycling participants were examined in three precisely defined cycle phases via ovulation testing. Both studies revealed that only P4 was correlated with HRV, such that higher-than-usual P4 significantly predicted lower-than-usual HRV within a given participant. In line with this, cycle phase comparisons revealed lower HRV in the mid-luteal phase (characterized by elevated P4) than in other phases. No significant main or interactive effects of E2 on HRV were found. Future female health studies should investigate individual differences in these effects and potential consequences of cyclical HRV changes on daily functioning.

The causal factors associated with increases in depressive symptoms among adolescent girls remain an area of theoretical debate, and the limited research considering a hormonal influence has provided mixed results. The goal of the present study was to test a set of longitudinal associations, that, if found, would provide support for a hormonal contribution to these changes. Specifically, this study tested the hypotheses that changes in depressive symptoms among adolescent girls would be associated with phase-specific symptoms of the menstrual cycle during early adulthood; that these associations would differ across three phases of the menstrual cycle; and that the pattern of associations would differ for changes in depressive symptoms during early- and late-adolescence. The sample consisted of 47 women with longitudinal data from 12 to 21 years old (approximately 91% European Canadian, 4% Middle Eastern Canadian, 2% Haitian Canadian, and 2% Asian Canadian). Consistent with expectations, results showed that early-adolescent increases in depressive symptoms were negatively associated with menstrual-phase negative affect, and positively associated with mid-cycle negative affect, but not associated with premenstrual negative affect; whereas late-adolescent change in depressive symptoms was only associated with depressive symptoms at 20-21 years. Thus, early-adolescent changes in depressive symptoms are longitudinally associated with later mood change across the menstrual cycle, suggesting a common underlying cause, which is hypothesized to be hormonal. Moreover, results suggest that, with respect to variables that are involved in affective development, important differences exist between early- and late-adolescence. The discussion considers menstrual-cycle-related symptoms (e.g., dysmenorrhea) during adolescence, and the need to study their effects on development. It is suggested that focused intervention and prevention efforts may be indicated to interrupt negative developmental outcomes.

There is a strong empirical connection between individual and peer substance use during adolescence. The determination of whether this level of covariation reflects influence or selection is obscured by both the design and measurement strategies used. This present study utilizes a short-term longitudinal design with bi-monthly assessments to address the following two hypotheses: a) Adolescents select friends on the basis of their substance use, and b) New friend substance use predicts changes in future use. French Canadian adolescents (n = 143) were interviewed on their friendship networks and substance use behaviors (e.g., tobacco, alcohol and marijuana) four times during a school year. Cross-lag panel models revealed that adolescents who use substances tend to select new friends who use. Moreover, once in the network, these new friends also contribute to changes in the adolescents' substance use. These findings are relevant to understanding the multiple functions of adolescent substance use. (Contains 1 table and 1 figure.)

This longitudinal study examined the covariation between parents' use of control and solicitation, youth willingness to self-disclose to parents, and youth antisocial behavior from ages 13 to 14. Structural equation analyses were conducted on a combined sample of Italian (N = 152) and French Canadian (N = 151) adolescents. Analyses tested for longitudinal cross-lagged effects while controlling for stability and all concurrent associations. Although bivariate correlations showed consistent associations among these constructs, both concurrently and over one year, SEM results revealed virtually no cross-lagged effects, after controlling for concurrent associations and stability. These findings suggest that the actual causal effects of parenting and youth behavior may best be conceptualized as occurring in the moment, rather than over extended periods of time. Results also showed that parental control and solicitation demonstrated very different associations with youth antisocial behavior, and should therefore be considered separately for research and prevention.

This study examined the effects of peer group rejection and a new group's norms on 7- and 9-year old children's intergroup attitudes. Children (N = 82) were rejected or accepted by an initial group, then accepted by a new group that had a norm of inclusion versus exclusion towards others. Results showed that rejected compared with accepted children had a more negative attitude towards the initial group, that they were equally positive towards their new group, but that the rejected children were more negative towards an outgroup. Results also revealed an age x target group x group norm effect that indicated that the younger children's attitudes towards the three groups were more negative in the exclusion versus acceptance norm condition. The older children were also more negative towards the initial and new groups in the exclusion condition, but their more positive attitudes towards the outgroup were unaffected by the group norms. The bases of the effects of peer group rejection and group norms are discussed.

In this study, two longitudinal models of early adolescent risky sexual behaviors (RSB) were compared using a pooled sample of 267 Canadian and Italian adolescents (55% females; 53% Canadians) assessed yearly from grade 8 to 10. We focused on parenting practices (monitoring, control, limit setting), adolescent problem behaviors (antisocial behaviors, substance use) and their friends' deviance (antisocial behaviors, substance use) as predictors of condom use frequency and lifetime number of sexual partners. The socialization model postulates that youths' problem behaviors and RSB are behaviors learned within the friendship network where deviancy training can occur. The selection model posits that delinquent youth tend to affiliate with each other, and that RSB is one of many behaviors that can form the basis of selection. Using structural equation modeling, this study showed that the socialization model was the most accurate to explain the emergence of RSB. A full mediation of parenting practices, passing through deviant friends and youths' problem behavior, was observed for condom use. The same process applied to number of sexual partners, but a direct effect for parenting practices was also found. (Contains 3 figures and 4 tables.)

This study was conducted to test whether the presence of new friends at moments of substance-use initiation differs across substances, and whether individuals tend to initiate substance use, across different substances, either with a new friend or with an old friend. Participants were 419 Italian high school students (41% female). Results showed that the presence of a new friend at the moment of substance-use initiation varied across different substances. New friends were least often present when an individual first tried cigarettes, and were most often present the first time an individual tried marijuana. Substance-use initiation in the co-presence of both an old friend and a new friend was almost exclusively linked to higher levels of substance use (marijuana and hard alcohol) and non-existent with tobacco use. However, results showed a clear tendency for individuals to initiate substance use either with a new friend or with an old friend. Results are discussed in terms of extending peer influence research to include transitions in peer relations as important moments for peer influence. (Contains 2 tables.)

The relations between antisocial behavior and depressive symptoms were examined both longitudinally and concurrently in a sample of Italian early-adolescents. Structural equation modelling was applied to 10-month longitudinal data from a sample of 107 youths (54 girls; mean age at baseline = M = 12.5). Early adolescents completed a questionnaire in which they reported antisocial behaviors and depressive symptoms. Results show temporal stability for both constructs. Moreover, results show a significant longitudinal relation between depression at t1 and antisocial behavior at t2. This relation dropped to not significant when controlling for concurrent relations between these two measures of psychosocial adjustment at t2. A multigroup comparison suggests that these findings are similar across gender. Implications of the results for theory and intervention are discussed.

This study examined the effects on 6- and 8-year old children (n = 160) of rejection versus acceptance by an initial group, the reason for the rejection or acceptance (personal versus category-based), and the norms (inclusion versus exclusion) of a new group to which the children were assigned, on their negative affect and attitudes towards the initial group, new group and an outgroup. Results showed that rejected compared with accepted children had a negative attitude towards the initial group, but that both were equally positive towards their new group. In addition, whereas accepted participants were less positive towards the outgroup, rejected participants displayed outgroup prejudice. Results also revealed main effects on group attitudes of participants' age and group norms, as well as a peer status x status reason interaction, but participants' negative affect was only affected by their age. The basis of the effect of peer group rejection on outgroup prejudice is discussed. (Contains 1 table.)

The present study was conducted to test the ability of two subscales from the Friendship Quality Questionnaire (FQQ; Parker & Asher, 1993) to discriminate between different target friendships. This was done by testing for mean differences between targets, and by using both exploratory and confirmatory factor analyses to examine the factor structures for these measures when the responses for different targets were considered together. Participants were 293 Italian middle-school students. Both subscales (Validation and Caring, and Conflict and Betrayal) showed mean differences between the best friend and the second and third best friends, but only the validation and caring subscale demonstrated differences between the second and third best friends. Factor analyses showed that for both subscales some items were able to discriminate between friends whereas others were not. Confirmatory factor analyses demonstrated the existence of target-specific factors, as well as a common "individual differences" factor. Practical and theoretical issues regarding the different sources of item variance are discussed.

Using a sample of 1227 Swedish adolescents we examined peer relations across contexts and for multiple peer targets (three ''Very Important Persons'', VIPs). Specifically, we examined the relations between antisocial behaviour and the types of relationships individuals had with their VIPs (e.g. friend, romantic partner), the contexts in which they had met, and where they spent time (e.g. school, neighbourhood, club). Additionally, we tested an ''additive homophily'' hypothesis, or the idea that youths would show unique similarities to multiple peers. Results showed that individuals who nominated romantic partners as their first VIPs were the most antisocial (both boys and girls), and individuals who had met and spent time with their first VIPs in the neighbourhood were also the most antisocial. Similar results were found for the antisocial behaviour of the first VIP. Finally, results supported the additive homophily hypothesis, showing that significantly more variance in individual behaviour is explained when including second and third VIPs.

Background: Premenstrual dysphoric disorder (PMDD) is a new Diagnostic and Statistical Manual of Mental Disorders (DSM)-5 diagnosis characterized by the cyclical emergence of emotional and physical symptoms in the luteal phase of the menstrual cycle, with symptom remission in the follicular phase. Converging evidence highlights the possibility of distinct subtypes of PMDD with unique pathophysiologies, but temporal subgroups have yet to be explored in a systematic way. Methods: In the current work, we use group-based trajectory modeling to identify unique trajectory subgroups of core emotional and total PMDD symptoms across the perimenstrual frame (days −14 to +9, where day 0 is menstrual onset) in a sample of 74 individuals prospectively diagnosed with DSM-5 PMDD. Results: For the total daily symptom score, the best-fitting model was comprised of three groups: a group demonstrating moderate symptoms only in the premenstrual week (65%), a group demonstrating severe symptoms across the full 2 weeks of the luteal phase (17.5%), and a group demonstrating severe symptoms in the premenstrual week that were slow to resolve in the follicular phase (17.5%). Conclusions: These trajectory groups are discussed in the context of the latest work on the pathophysiology of PMDD. Experimental work is needed to test for the presence of possible pathophysiologic differences in trajectory groups, and whether unique treatment approaches are needed. [ABSTRACT FROM AUTHOR]