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Background The enduring impact of childhood maltreatment on biological systems and ensuing psychopathology remains incompletely understood. Long-term effects of stress may be reflected in cumulative cortisol secretion over several months, which is now quantifiable via hair cortisol concentrations (HCC). We conducted a first comprehensive investigation utilizing the potential of hair cortisol analysis in a large sample of maltreated and nonmaltreated children and adolescents. Method Participants included 537 children and adolescents (3 to 16 years; 272 females) with maltreatment (n = 245) or without maltreatment histories (n = 292). Maltreated subjects were recruited from child protection services (CPS; n = 95), youth psychiatric services (n = 56), and the community (n = 94). Maltreatment was coded using the Maltreatment Classification System drawing on caregiver interviews and complemented with CPS records. Caregivers and teachers reported on child mental health. HCC were assessed in the first 3 cm hair-segment. Results Analyses uniformly supported that maltreatment coincides with a gradual and dose-dependent reduction of HCC from 9-10 years onwards relative to nonmaltreated controls. This pattern emerged consistently from both group-comparisons between maltreated and nonmaltreated subjects (27.6% HCC reduction in maltreated 9 to 16-year-olds) and dimensional analyses within maltreated subjects, with lower HCC related to greater maltreatment chronicity and number of subtypes. Moreover, both group comparisons and dimensional analyses within maltreated youth revealed that relative HCC reduction mediates the effect of maltreatment on externalizing symptoms. Conclusions From middle childhood onwards, maltreatment coincides with a relative reduction of cortisol secretion, which, in turn, may predispose to externalizing symptoms.

We presented three types of animations on an eye tracking monitor to 31 adult participants. In line with previous work, verbal descriptions of these animations indicate that one type (theory of mind or ToM) evokes mental state attributions, while another type (random) does not, with an intermediate category (goal-directed) evoking a moderate amount of mental state attributions. We expected longer fixations with greater depth of processing, which we assume is required for mental state attributions. In line with this expectation we found that the ToM animations invited long fixations; the random animations invited short fixations, while the goal-directed animations invited an intermediate amount of fixations, with some clips inviting shorter and others longer fixations. These findings demonstrate that it is possible to capture systematic differences in behaviour while viewing animations not only by means of a verbal measure, but also in terms of a simple measure of eye movements.

The Strengths and Difficulties Questionnaire (SDQ) is an internationally recognized and widely used screening instrument consisting of 25 items that address positive and negative behavioral attributes of children and adolescents. This paper investigates some of the psychometric properties of the German parent-rated SDQ examining preschool-age children. The sample consisted of 1,738 children – 840 girls and 898 boys – between 3 and 5 years of age. Parents completed the SDQ and gave basic demographical information. All subscales were sufficiently homogeneous. Principal component analysis suggested both a five-factor solution (replicating the original five-factor structure) and a three-factor solution. Confirmatory factor analyses showed a better fit for the five-factor model than for the three-factor model. A comparison between the preschool sample and the German normative sample revealed differences in some subscales. Furthermore, there were gender differences in almost all subscales, with boys showing significantly higher problem scores than girls (except for emotional symptoms) and lower scores on the prosocial behavior scale. Parental education proved to be associated with SDQ scores. This study confirmed that the parent-rated SDQ is a reliable and useful instrument for preschoolers and is recommended for screening purposes.

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BackgroundEctoparasitic infections are of particular interest for endangered wildlife, as ectoparasites are potential vectors for inter- and intraspecific pathogen transmission and may be indicators to assess the health status of endangered populations. Here, ectoparasite dynamics in sympatric populations of two Malagasy mouse lemur species, Microcebus murinus and M. ravelobensis, were investigated over an 11-month period. Furthermore, the animals’ body mass was determined as an indicator of body condition, reflecting seasonal and environmental challenges. Living in sympatry, the two study species experience the same environmental conditions, but show distinct differences in socioecology: Microcebus murinus sleeps in tree holes, either solitarily (males) or sometimes in groups (females only), whereas M. ravelobensis sleeps in mixed-sex groups in more open vegetation.ResultsBoth mouse lemur species hosted ticks (Haemaphysalis sp.), lice (Lemurpediculus sp.) and mites (Trombiculidae gen. sp. and Laelaptidae gen. sp.). Host species, as well as temporal variations (month and year), were identified as the main factors influencing infestation. Tick infestation peaked in the late dry season and was significantly more often observed in M. murinus (P = 0.011), while lice infestation was more likely in M. ravelobensis (P < 0.001) and showed a continuous increase over the course of the dry season. Genetic analyses identified Lemurpediculus sp. infesting both mouse lemur species. Ticks morphologically conform to H. lemuris, but genetic analysis showed a clear differentiation of the specimens collected in this study, suggesting a potentially new tick species. Host body mass decreased from the early to the late dry season, indicating nutritional stress during this period, which may render individuals more susceptible to parasitic infections.ConclusionsSeasonal differences and species-specific variations in sleeping site ecology in terms of sleeping site type and sociality were determined as key factors influencing ectoparasitism in M. murinus and M. ravelobensis. This needs to be taken into account when evaluating ectoparasite infestations at a given time point. The detection of the same parasite species on two closely related and sympatric host species furthermore indicates a potential pathway for disease transmission, not only within but also between lemur species.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-3034-y) contains supplementary material, which is available to authorized users.

Practitioners and researchers alike face the challenge that different sources report inconsistent information regarding child maltreatment. The present study capitalizes on concordance and discordance between different sources and probes applicability of a multisource approach to data from three perspectives on maltreatment-Child Protection Services (CPS) records, caregivers, and children. The sample comprised 686 participants in early childhood (3- to 8-year-olds; n = 275) or late childhood/adolescence (9- to 16-year-olds; n = 411), 161 from two CPS sites and 525 from the community oversampled for psychosocial risk. We established three components within a factor-analytic approach: the shared variance between sources on presence of maltreatment (convergence), nonshared variance resulting from the child's own perspective, and the caregiver versus CPS perspective. The shared variance between sources was the strongest predictor of caregiver- and self-reported child symptoms. Child perspective and caregiver versus CPS perspective mainly added predictive strength of symptoms in late childhood/adolescence over and above convergence in the case of emotional maltreatment, lack of supervision, and physical abuse. By contrast, convergence almost fully accounted for child symptoms for failure to provide. Our results suggest consistent information from different sources reporting on maltreatment is, on average, the best indicator of child risk.

Social dilemmas are characterized by conflicts between immediate self-interest and long-term collective goals. Although such conflicts lie at the heart of various challenging social interactions, we know little about how cooperation in these situations develops. To extend work on social dilemmas to child and adolescent samples, we developed an ageappropriate computer task (the Pizzagame) with the structural features of a public goods game (PGG). We administered the Pizzagame to a sample of 191 children 9 to 16 years of age. Subjects were led to believe they were playing the game over the Internet with three sets of two same-aged, same-sex coplayers. In fact, the co-players were computer-generated and programmed to expose children to three consecutive conditions: (1) a cooperative strategy, (2) a selfish strategy, and (3) divergent cooperative-selfish strategies. Supporting the validity of the Pizzagame, our results revealed that children and adolescents displayed conditional cooperation, such that their contributions rose with the increasing cooperativeness of their co-players. Age and gender did not influence children and adolescents' cooperative behavior within each condition.However, older children adapted their behavior more flexibly between conditions to parallel the strategies of their coplayers. These results support the utility of the Pizzagame as a feasible, reliable, and valid instrument for assessing and quantifying child and adolescent cooperative behavior. Moreover, these findings extend previous work showing that age influences cooperative behavior in the PGG.