A Systematic Review and Meta-Analysis: Child and Adolescent Healthcare Utilization for Eating Disorders During the COVID-19 Pandemic.

OBJECTIVE: To conduct a meta-analysis documenting healthcare service utilization rates for pediatric (age <19 years) eating disorders during compared to before the COVID-19 pandemic. METHOD: PsycINFO, MEDLINE, Embase, and Web of Science Core Collection were searched for studies published up to May 19, 2023. Studies with pediatric visits to primary care, inpatient, outpatient, and emergency department for eating disorders before and during the pandemic were included. This preregistered review (PROSPERO CRD42023413392) was reported using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data were analyzed with random-effects meta-analyses. RESULTS: A total of 52 studies reporting >148,000 child and adolescent eating disorder-related visits to >300 health settings across 15 countries were included (mean age, 12.7 years; SD = 4.1 years; 87% girls). There was strong evidence of an increase in healthcare use for eating disorders during the pandemic (rate ratio [RR] = 1.54, 95% CI = 1.38-1.71). Moderator analysis revealed larger rate increases among girls (RR = 1.48, 95% CI = 1.28-1.71) compared to boys (RR = 1.24, 95% CI = 1.06-1.45) and for adolescents (age ≥12 to 19 years) (RR = 1.53, 95% CI = 1.29-1.81) compared to children (RR = 0.87, 95% CI = 0.53-1.43). Moderator analysis demonstrated strong evidence of increased use of emergency department (RR = 1.70, 95% CI = 1.48-1.97), inpatient (RR = 1.56, 95% CI = 1.33-1.84), and outpatient (RR = 1.62, 95% CI = 1.35-1.95) services, as well as strong evidence of increased rates of anorexia nervosa (RR = 1.48, 95% CI = 1.24-1.75). CONCLUSION: Healthcare use for pediatric eating disorders increased substantially during the COVID-19 pandemic, particularly among girls and adolescents. It is important to continue to monitor whether changes in healthcare use associated with acute pediatric mental distress are sustained beyond the COVID-19 pandemic. STUDY PREREGISTRATION INFORMATION: Risk factors for eating disorders for youth during the COVID-19 pandemic; https://www.crd.york.ac.uk/; CRD42023413392. DIVERSITY & INCLUSION STATEMENT: One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. One or more of the authors of this paper self-identifies as living with a disability. We actively worked to promote sex and gender balance in our author group. We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group. While citing references scientifically relevant for this work, we also actively worked to promote sex and gender balance in our reference list. While citing references scientifically relevant for this work, we also actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our reference list. The author list of this paper includes contributors from the location and/or community where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the work. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented sexual and/or gender groups in science.

Social Media Friendship Jealousy.

A new measure to assess friendship jealousy in the context of social media was developed. This one-factor, seven-item measure was psychometrically sound, showing evidence of validity and reliability in three samples of North American adults (Study 1, n = 491; Study 2, n = 494; Study 3, n = 415) and one-, two-, and three-year stability (Study 3). Women reported more social media friendship jealousy than men (Studies 2 and 3) and younger women had the highest levels of social media friendship jealousy (compared with younger men and older men and women; Study 2). Social media friendship jealousy was associated with lower friendship quality (Study 1) and higher social media use and trait jealousy (Study 2). The relation between social media friendship jealousy and internalizing symptoms indicated positive within time associations and longitudinal bidirectional relations (Study 3). Specifically, social media friendship jealousy predicted increases in internalizing problems, and internalizing problems predicted greater social media friendship jealousy accounting for gender and trait levels of social media friendship jealousy and internalizing problems. Anxious and depressed adults may be predisposed to monitor threats to their friendships via social media and experience negative consequences because of this behavior. Although social media interactions can be associated with positive well-being and social connectedness, our results highlight that they can also undermine friendships and mental health due to jealousy.

Love withdrawal use by toddlers: Multi-informant associations with aggression and parents' use of love withdrawal.

Love withdrawal is a form of interpersonal manipulation that shares many features with relational aggression; its use by children has not been examined. Guided by social learning theory, we sought to investigate the prevalence of toddlers' use of love withdrawal toward caregivers (parents and teachers) and further investigate how this behavior was associated with relational and physical aggression and parents' use of love withdrawal. These aims were examined using parent and teacher reports in a sample of 198 toddlers (Mage = 33.62 months; SD = 5.00 months; 50.5% girls). We found that most toddlers used love withdrawal directed at parents (79.2%) and teachers (72.1%) when angry and displayed this type of behavior more than relational and physical aggression. Accounting for household income, hours per week in childcare, and child age in months, as well as classroom clustering, we found that relational aggression, and not physical aggression, predicted the use of love withdrawal by toddlers (teacher reports), and that the associations were stronger for love withdrawal and relational aggression than for physical aggression. We also found that parents' use of love withdrawal toward their child was correlated with their reports of their child's use of love withdrawal, but not with their child's use of aggression. These results highlight the importance of considering the use of love withdrawal by children given its association with aggression which is linked to poorer psychosocial functioning.

Stress-related cellular pathophysiology as a crosstalk risk factor for neurocognitive and psychiatric disorders.

In this narrative review, we examine biological processes linking psychological stress and cognition, with a focus on how psychological stress can activate multiple neurobiological mechanisms that drive cognitive decline and behavioral change. First, we describe the general neurobiology of the stress response to define neurocognitive stress reactivity. Second, we review aspects of epigenetic regulation, synaptic transmission, sex hormones, photoperiodic plasticity, and psychoneuroimmunological processes that can contribute to cognitive decline and neuropsychiatric conditions. Third, we explain mechanistic processes linking the stress response and neuropathology. Fourth, we discuss molecular nuances such as an interplay between kinases and proteins, as well as differential role of sex hormones, that can increase vulnerability to cognitive and emotional dysregulation following stress. Finally, we explicate several testable hypotheses for stress, neurocognitive, and neuropsychiatric research. Together, this work highlights how stress processes alter neurophysiology on multiple levels to increase individuals' risk for neurocognitive and psychiatric disorders, and points toward novel therapeutic targets for mitigating these effects. The resulting models can thus advance dementia and mental health research, and translational neuroscience, with an eye toward clinical application in cognitive and behavioral neurology, and psychiatry.

Anxiety symptoms before and during the COVID-19 pandemic: A longitudinal examination of Canadian young adults.

The COVID-19 pandemic has resulted in many changes that may impact anxiety symptoms (i.e., general anxiety and somatization), particularly for young adults who were at higher risk for anxiety than older adults. We examined anxiety symptoms before (age 19, 20, 21, and 22) and during the pandemic (age 23 and 24) in a cohort of Canadian young adults (n = 396). Latent growth curve models were performed for general anxiety and somatization and the pandemic time points were estimated as structured residuals to quantify the change from participants' expected trajectories. We also examined whether fear of COVID-19 predicted the changes in anxiety symptoms during the pandemic. Results indicated that a history of general anxiety and somatization positively predicted fear of COVID-19 during the pandemic and negatively predicted pandemic change from predicted values for both general anxiety and somatization. Increased COVID-19 fear was related within time to increases in general anxiety at ages 23 and 24 and increases in somatization at age 24. We also found that the proportion of individuals in the subclinical/clinical range of somatization was higher from age 23-24, but not from age 22-23 and there were no differences for general anxiety. Results highlight the need to consider within-person change and development in evaluating anxiety symptom changes and predictors of changes in anxiety symptoms.

Bullying before and during the COVID-19 pandemic.

The rates of bullying during the COVID-19 pandemic, a time of unprecedented public health and social restrictions, were compared to earlier times when students attended school in person. Several studies indicated a notable decrease in the prevalence of bullying victimization and perpetration during the pandemic, particularly when online learning was implemented. But studies from countries with fewer social restrictions indicated increases in rates of bullying during the pandemic. Mixed results regarding prevalence rates for some bullying forms (e.g., cyberbullying) were also found. Racialized youth and LGBTQ+ youth reliably reported higher rates of bullying victimization during the pandemic, consistent with pre-pandemic patterns. Reasons for the inconsistencies in findings likely relate to diverse methods, timeframes, and sampling techniques, as well as different experiences with pandemic social restrictions. More longitudinal studies are needed to assess whether bullying involvement did in fact "change" during, compared to before, the pandemic. The findings point to the importance of peer relationships and hint at the potential of increased teacher supervision as a bullying prevention strategy.

Trajectories, comorbidity, and risk factors for adolescent disordered eating and borderline personality disorder features.

PURPOSE: Borderline personality disorder (BPD) and eating disorders are highly comorbid, but the shared course of symptoms and associated risks remain poorly understood. The aim of this study was to examine joint symptom trajectories, temporal precedence, risk factors, and population attributable fractions (PAFs) in a community sample of adolescents, using a developmental psychopathology and psychosocial framework. METHODS: Across five years (age 14-18 years), adolescents (n = 544, 56% girls) reported on BPD features and disordered eating behavior. Sociodemographic, interpersonal, and clinical risks were assessed in childhood (age 10-13 years). We used a person-centered approach to examine latent class growth analyses, joint trajectory models, and calculated PAFs. RESULTS: Three-class solutions were found for both disordered eating and BPD features (low, moderate, high), creating nine joint trajectories. High levels of disordered eating were a stronger indicator of high levels of BPD features than was the reverse. Girls and LGBTQ+ youth were most likely to be in a high symptom trajectory. Bullying perpetration and clinical hyperactivity were unique risks for BPD features. Bullying victimization contributed the largest PAF to disordered eating and BPD features. CONCLUSION: We identified several novel and clinically relevant findings related to temporality, risks, screening, and the treatment of adolescent eating problems and BPD.

Experiences of racial microaggression among immigrant and Canadian-born young adults: Effects of double stigma on mental health and service use.

BACKGROUND: Significant disparities in utilization of mental health services exist among immigrant and Canadian-born populations. These gaps may be associated with a 'double stigma' - stigma related to being from a racialized background exacerbated by mental health stigma. Immigrant young adults may be particularly susceptible to this phenomenon, given developmental and social transitions from adolescence to adulthood. AIMS: To investigate the joint effects of racial microaggression and mental health stigma on mental health and service use among first-generation immigrant and Canadian-born university students. METHOD: We conducted an online cross-sectional study among first-generation immigrant and Canadian-born university students (N = 1,280, Mage = 19.10, SD = 1.50). RESULTS: Despite no differences in anxiety or depression symptoms, first-generation (foreign-born) immigrants were less likely to have received therapy and to have taken medication for mental health issues compared to Canadian-born participants. First-generation immigrants also reported experiencing higher levels of racial microaggression and stigma toward service use. Results suggest the presence of a double stigma, mental health stigma and racial microaggression, each explained significant additional variance in symptoms of anxiety and depression and medication use. No effects of double stigma for therapy use were found - while higher mental health stigma predicted lower use of therapy, racial microaggression did not predict unique variance in therapy use. CONCLUSIONS: Our findings highlight the joint effects of racial microaggression and stigma toward mental health and service as barriers to help-seeking among immigrant young adults. Mental health intervention and outreach programmes should target overt and covert forms of racial discrimination while incorporating culturally sensitive anti-stigma approaches to help reduce disparities in mental health service use among immigrants in Canada.

Changes in Depression and Anxiety Among Children and Adolescents From Before to During the COVID-19 Pandemic: A Systematic Review and Meta-analysis.

Importance: There is a growing body of high-quality cohort-based research that has examined changes in child and adolescent mental health during the COVID-19 pandemic vs before the pandemic. Some studies have found that child and adolescent depression and anxiety symptoms have increased, while others have found these symptoms to have remained stable or decreased. Objective: To synthesize the available longitudinal cohort-based research evidence to estimate the direction and magnitude of changes in depression and anxiety symptoms in children and adolescents assessed before and during the pandemic. Data Sources: Medline, Embase, and PsycInfo were searched for studies published between January 1, 2020, and May 17, 2022. Study Selection: Included studies reported on depression and/or anxiety symptoms, had cohort data comparing prepandemic to pandemic estimates, included a sample of children and/or adolescents younger than 19 years, and were published in English in a peer-reviewed journal. Data Extraction and Synthesis: In total, 53 longitudinal cohort studies from 12 countries with 87 study estimates representing 40 807 children and adolescents were included. Main Outcomes and Measures: Standardized mean changes (SMC) in depression and anxiety symptoms from before to during the pandemic. Results: The analysis included 40 807 children and adolescents represented in pre-COVID-19 studies and 33 682 represented in during-COVID-19 studies. There was good evidence of an increase in depression symptoms (SMC, 0.26; 95% CI, 0.19 to 0.33). Changes in depression symptoms were most conclusive for study estimates among female individuals (SMC, 0.32; 95% CI, 0.21 to 0.42), study estimates with mid to high income (SMC, 0.35; 95% CI, 0.07 to 0.63), and study estimates sourced from North America (SMC, 0.25; 95% CI, 0.15 to 0.36) and Europe (SMC, 0.35; 95% CI, 0.17 to 0.53). There was strong evidence that anxiety symptoms increased slightly during the pandemic (SMC, 0.10; 95% CI, 0.04 to 0.16), and there was some evidence of an increase in study estimates with mid to high income. Conclusions: This systematic review and meta-analysis of longitudinal studies including children and adolescents found an increase in depression symptoms during the COVID-19 pandemic, particularly among female individuals and those from relatively higher-income backgrounds.

Longitudinal associations between academic achievement and depressive symptoms in adolescence: Methodological considerations and analytical approaches for identifying temporal priority.

Failure to meet educational expectations in adolescence can derail an individual's potential, leading to hardship in adulthood. Lower academic achievement is also associated with poorer mental health, and both share common pathways to adult functional outcomes like employment status and economic security. Although linked in adolescence, and predictive of similar outcomes in adulthood, methodological and analytical limitations of the literature do not permit the assessment of the temporal priority between academic achievement and mental health. This omission of directionality hampers intervention and prevention efforts. In this narrative review, we summarize the literature on the temporal ordering between academic achievement and depressive symptoms in adolescence, a particularly vulnerable developmental period. We propose methodological and analytical strategies to guide future research to disentangle the chronological ordering between academic achievement and depressive symptoms-recommendations that can be used to examine other sets of correlated variables over time. Specifically, we highlight methodological issues that require attention such as the need to understand reciprocal and cascading influences over time by attending to repeated measures and timing, measurement consistency, reporter effects, examination of processes and mechanisms, and missing data. Finally, we discuss the need to embrace analytical methods that separate within-person from between-person effects; account for heterogeneity in associations using person-centered approaches; and use the two approaches as complementary, rather than competing, for a more holistic examination of temporality.

Variable patterns of daily activity participation across settings in autistic youth: A latent profile transition analysis.

LAY ABSTRACT: What people do or engage in in their daily lives, or daily life participation, is often linked to their state of being happy and healthy, as well as potential for living independently. To date, little research has been conducted on daily activity participation by autistic youth at home, at school or in the community. Learning more about individual differences in participation levels and what might influence them can help to create custom supports for autistic youth and their families. In this study, 158 caregivers of autistic youth were asked how often their children took part in 25 common activities at two assessments, about one year apart. The analysis showed three profiles for each of the home and school settings and two profiles for the community setting. These profiles reflected distinct patterns in how often autistic youth took part in various daily activities, particularly in doing homework, school club activities and community gatherings. Most autistic youth were in profiles marked by often taking part at home but less often at school and in the community, and about three-fourths of them tended to stay in the same profile over time. Autistic youth with limited participation profiles were more likely to have lower scores on measures of cognitive ability and daily life skills and more challenging behaviour, and faced more barriers in their environment. These findings show how important it is to think about each autistic person's strengths and weaknesses, and changing needs, to better support their daily life participation.

Bullying involvement and the transition to high school: A brief report.

School transitions are common educational experiences for children and adolescents and many of them worry about being bullied during this type of major life-changing point. In a sample of 701 Canadians assessed yearly from grade 5 (age 10) to grade 12 (age 18), we examined heterogeneous patterns of bullying involvement while statistically accounting for the transition into high school. Gender differences were also examined. Results indicated that on average, bullying victimization declined over time with a significant drop noted between grade 8 and grade 9 (the transition into high school), with few differences between girls and boys. Bullying perpetration also declined for most students (no gender differences), with a notable drop found at the transition into high school. However, for a subset of adolescents, the transition into high school was accompanied by an increase in bullying perpetration. These varied experiences highlight the need to model heterogeneity when examining the impact of school transitions on bullying, a neglected focus of inquiry to date. Our results suggest that moving into high school is beneficial for most adolescents involved in bullying, but not for all.

Comparison of paediatric emergency department visits for attempted suicide, self-harm, and suicidal ideation before and during the COVID-19 pandemic: a systematic review and meta-analysis.

BACKGROUND: There is a lack of consensus about the effect of the COVID-19 pandemic on the mental health of children and adolescents. We aimed to compare rates of paediatric emergency department visits for attempted suicide, self-harm, and suicidal ideation during the pandemic with those before the pandemic. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, and PsycINFO for studies published between Jan 1, 2020, and Dec 19, 2022. Studies published in English with data on paediatric (ie, those aged <19 years) emergency department visits before and during the COVID-19 pandemic were included. Case studies and qualitative analyses were excluded. Changes in attempted suicide, self-harm, suicidal ideation, and other mental-illness indicators (eg, anxiety, depression, and psychosis) were expressed as ratios of the rates of emergency department visits during the pandemic compared with those before the pandemic, and we analysed these with a random-effects meta-analysis. This study was registered with PROSPERO, CRD42022341897. FINDINGS: 10 360 non-duplicate records were retrieved, which yielded 42 relevant studies (with 130 sample-estimates) representing 11·1 million emergency department visits for all indications of children and adolescents across 18 countries. The mean age of the samples of children and adolescents across studies was 11·7 years (SD 3·1, range 5·5-16·3), and there were on average 57·6% girls and 43·4% boys as a proportion of emergency department visits for any health reasons (ie, physical and mental). Only one study had data related to race or ethnicity. There was good evidence of an increase in emergency department visits for attempted suicide during the pandemic (rate ratio 1·22, 90% CI 1·08-1·37), modest evidence of an increase in emergency department visits for suicidal ideation (1·08, 0·93-1·25), and good evidence for only a slight change in self-harm (0·96, 0·89-1·04). Rates of emergency department visits for other mental-illness indications showed very good evidence of a decline (0·81, 0·74-0·89), and paediatric visits for all health indications showed strong evidence of a reduction (0·68, 0·62-0·75). When rates for attempted suicide and suicidal ideation were combined as a single measure, there was good evidence of an increase in emergency department visits among girls (1·39, 1·04-1·88) and only modest evidence of an increase among boys (1·06, 0·92-1·24). Self-harm among older children (mean age 16·3 years, range 13·0-16·3) showed good evidence of an increase (1·18, 1·00-1·39), but among younger children (mean age 9·0 years, range 5·5-12·0) there was modest evidence of a decrease (0·85, 0·70-1·05). INTERPRETATION: The integration of mental health support within community health and the education system-including promotion, prevention, early intervention, and treatment-is urgently needed to increase the reach of mental health support that can mitigate child and adolescent mental distress. In future pandemics, increased resourcing in some emergency department settings would help to address their expected increase in visits for acute mental distress among children and adolescents. FUNDING: None.

Loneliness and Well-Being in Children and Adolescents during the COVID-19 Pandemic: A Systematic Review.

Concerns have been raised about the loneliness and well-being of children and adolescents during the COVID-19 pandemic. The extent to which the ongoing pandemic has impacted loneliness and the association between loneliness and well-being is unclear. Therefore, a systematic review of empirical studies on the COVID-19 pandemic was conducted to examine the (1) prevalence of loneliness in children and adolescents, (2) associations between loneliness and indicators of well-being, and (3) moderators of these associations. Five databases (MEDLINE, Embase, PsycInfo, Web of Science, ERIC) were searched from 1 January 2020 to 28 June 2022 and 41 studies met our inclusion criteria (cross-sectional: n = 30; longitudinal: n = 11; registered on PROSPERO: CRD42022337252). Cross-sectional prevalence rates of pandemic loneliness varied, with some finding that over half of children and adolescents experienced at least moderate levels of loneliness. Longitudinal results reflected significant mean increases in loneliness compared to pre-pandemic levels. Cross-sectional results indicated that higher levels of loneliness were significantly associated with poorer well-being, including higher depression symptoms, anxiety symptoms, gaming addiction, and sleep problems. Longitudinal associations between loneliness and well-being were more complex than cross-sectional associations, varying by assessment timing and factors in the statistical analyses. There was limited diversity in study designs and samples, preventing a thorough examination of moderating characteristics. Findings highlight a broader challenge with child and adolescent well-being that predates the pandemic and the need for future research to examine underrepresented populations across multiple timepoints.

Longitudinal associations between early childhood irritability and adolescent depression symptoms in autistic children are mediated by peer relationships but not educational engagement.

In the general population, irritability is associated with later depression. Despite irritability being more prevalent in autistic children, the long-term sequelae are not well explored. We tested whether irritability in early childhood predicted depression symptoms in autistic adolescents, and whether associations could be explained by difficulties in peer relationships and lower educational engagement. Analyses tested the longitudinal associations between early childhood irritability (ages 3-5) and adolescent depression symptoms (age 14) in a prospective inception cohort of autistic children (N = 390), followed from early in development shortly after they received a clinical diagnosis. Mediators were measured in mid-childhood (age 10) by a combination of measures, from which latent factors for peer relationships and educational engagement were estimated. Results showed early childhood irritability was positively associated with adolescent depression symptoms, and this association remained when adjusting for baseline depression. A significant indirect pathway through peer relationships was found, which accounted for around 13% of the association between early childhood irritability and adolescent depression, suggesting peer problems may partially mediate the association between irritability and later depression. No mediation effects were found for education engagement. Results highlight the importance of early screening and intervention for co-occurring irritability and peer problems in young autistic children.

The Influence of Bilingual Language Exposure on the Narrative, Social and Pragmatic Abilities of School-Aged Children on the Autism Spectrum.

We examined the narrative abilities of bilingual and monolingual children on the autism spectrum (AS), whether bilinguals presented stronger social and pragmatic language abilities compared to monolinguals, and the link between narrative, social, and pragmatic language abilities.The narrative, social, and pragmatic language skills of school-aged bilinguals (n = 54) and monolinguals (n = 80) on the AS were assessed using normed measures. Language exposure was estimated through a parent questionnaire.Bilinguals performed similarly to monolinguals on measures of narrative, social, and pragmatic language skills. However, balanced bilinguals performed better on a nonliteral language task.Overall, results indicate that bilingual children on the AS can become as proficient in using language as monolinguals and may enjoy a bilingual advantage.

Disentangling global and domain-level adaptive behavior trajectories among children with autism spectrum disorder.

BACKGROUND: Heterogeneity in adaptive behavior abilities among people with autism spectrum disorder (ASD) is expressed not only as uneven levels of impairment across domains, but also in the developmental trajectories of adaptive skills. We studied the question of whether, after accounting for global adaptive behavior development, we find evidence of heterogeneity in the trajectories of specific domains of adaptive behavior. METHODS: A sample of 504 children with ASD was obtained by combining data from two independent natural history studies conducted in North America. We used a factor of curves model to explain growth between 36 and 138 months in Vineland Adaptive Behavior Scales, Second Edition (VABS) age equivalents as a function of domain-specific and global growth processes. RESULTS: The domain-specific trajectories in all three domains (Communication, Daily Living Skills, and Socialization) reflected impairment relative to age expectations as well as slower-than-expected growth with age, and the parameters of these trajectories were moderately-to-strongly correlated across domains. The global adaptive behavior trajectory had an initial (36-41 months of age) developmental level of about 22 age-equivalent months, and eventually slowed after initially increasing by about 6 months each year. The global trajectory accounted for the majority of variance in the domain-level processes; however, additional variance remained (14%-38%) in the domain-level intercepts, slopes, and quadratic processes. CONCLUSIONS: These results extend existing theoretical and empirical support for the hierarchical structure of adaptive behavior to include its development over time in clinical samples of children with ASD. A latent global trajectory may be sufficient to describe the growth of adaptive behavior in children with ASD; however, the remaining domain-specific variability after accounting for global adaptive behavior development allows for the possibility that differential effects of intervention on specific domains may be possible and detectable.

Continuity of trajectories of autism symptom severity from infancy to childhood.

BACKGROUND: Behavioral symptom trajectories are informative of the development of young children at increased likelihood for autism spectrum disorder (ASD). METHODS: Developmental trajectories of early signs were examined in a cohort of siblings of children diagnosed with ASD (n = 502) from 6 to 18 months using the Autism Observation Scale for Infants (AOSI), and from 18 months to 5-7 years using the Autism Diagnostic Observation Schedule (ADOS). Diagnostic outcomes for ASD at age 3 confirmed diagnosis for 137 children. We further analyzed the conditional probability of a switch from a trajectory measured with the AOSI to a trajectory measured with the ADOS as well as predictors from age 6 months. RESULTS: We derived three early trajectories of behavioral signs ("Low," "Intermediate," and "Increasing") from 6 to 18 months using the AOSI. We then derived three similar, distinct trajectories for the evolution of symptom severity between 18 and 60-84 months of age (Low, Intermediate, Increasing) using the ADOS. Globally, the Low trajectory included children showing fewer ASD signs or symptoms and the Increasing trajectory included children showing more severe symptoms. We also found that most children in the Low AOSI trajectory stayed in the corresponding ADOS trajectory, whereas children in an Increasing AOSI trajectory tended to transition to an Intermediate or Increasing ADOS trajectory. Developmental measures taken at 6 months (early signs of ASD, Fine Motor, and Visual Reception skills) were predictive of trajectory membership. CONCLUSIONS: Results confirm substantial heterogeneity in the early emergence of ASD signs in children at increased likelihood for ASD. Moreover, we showed that the way those early behavioral signs emerge in infants is predictive of later symptomatology. Results yield clear clinical implications, supporting the need to repeatedly assess infants at increased likelihood for ASD as this can be highly indicative of their later development and behavior.