Neuroimaging Association Scores: reliability and validity of aggregate measures of brain structural features linked to mental disorders in youth.

In genetics, aggregation of many loci with small effect sizes into a single score improved prediction. Nevertheless, studies applying easily replicable weighted scores to neuroimaging data are lacking. Our aim was to assess the reliability and validity of the Neuroimaging Association Score (NAS), which combines information from structural brain features previously linked to mental disorders. Participants were 726 youth (aged 6-14) from two cities in Brazil who underwent MRI and psychopathology assessment at baseline and 387 at 3-year follow-up. Results were replicated in two samples: IMAGEN (n = 1627) and the Healthy Brain Network (n = 843). NAS were derived by summing the product of each standardized brain feature by the effect size of the association of that brain feature with seven psychiatric disorders documented by previous meta-analyses. NAS were calculated for surface area, cortical thickness and subcortical volumes using T1-weighted scans. NAS reliability, temporal stability and psychopathology and cognition prediction were analyzed. NAS for surface area showed high internal consistency and 3-year stability and predicted general psychopathology and cognition with higher replicability than specific symptomatic domains for all samples. They also predicted general psychopathology with higher replicability than single structures alone, accounting for 1-3% of the variance, but without directionality. The NAS for cortical thickness and subcortical volumes showed lower internal consistency and less replicable associations with behavioural phenotypes. These findings indicate the NAS based on surface area might be replicable markers of general psychopathology, but these links are unlikely to be causal or clinically useful yet.

Do early difficult temperament and harsh parenting differentially predict reactive and proactive aggression?

The goal of this study was to examine the links between difficult temperament (i.e., negative emotionality) and harsh parental discipline during toddlerhood, and reactive and proactive aggression in kindergarten. These links were assessed on a longitudinal population-based study of 1516 boys and girls followed longitudinally from the age of 17 months through the age of 72 months. Two possible models were tested to examine the interplay between negative emotionality and harsh parenting in predicting later reactive aggression compared to proactive aggression. The first was an additive model where both aspects make unique contributions in predicting later reactive aggression. The second model was an interactive model where harsh parenting exacerbates the link between negative emotionality and reactive aggression. Results showed a specific contribution of negative emotionality to reactive aggression. The results relative to harsh parenting are more mixed but nonetheless in line with developmental models stressing different pathways to reactive and proactive aggression.

Natural history of suicidal behaviors in a population-based sample of young adults.

BACKGROUND: Suicidal behaviors in young individuals represent an important public health problem. Understanding their natural history and relationships would therefore be of clinical and research value. In this study, we examined the natural histories of several suicidal behaviors and investigated two conceptual models of suicidality (dimensional and categorical) in the context of adolescent and adult-onset suicide attempts. METHOD: Participants were members of a prospectively studied, representative, population-based school cohort followed since age 6 (n = 3017) through mid-adolescence (n = 1715) to their early twenties (n = 1684). Outcome measures included suicidal ideation, attempts and completions. RESULTS: Approximately one in 500 individuals died by suicide. About 33% had suicidal ideas and 9.3% made at least one suicide attempt. Over half (4.9%) of the self-reported attempters made their first attempt before age 18. With the exception of current suicidal ideas, non-fatal suicidal behaviors were more prevalent in females. In general, parental and cross-sectional self-reports underestimated suicidality rates. Aikaike (AIC) and Bayesian (BIC) information criteria suggested the ordinal model, and dimensional conceptualization of suicide attempts of different onset age, to be more optimal than its multinomial/categorical counterpart (ordinal: AIC 567.55, BIC 635.67; multinomial: AIC 616.59, BIC 723.83). Both models, nevertheless, identified five common factors of relevance to suicidal diathesis: gender, disruptive disorders, childhood anxiousness and abuse, and suicidal thoughts. CONCLUSIONS: Non-fatal suicidal behaviors in adolescents and young adults are more common than suggested by cross-sectional studies and parental reports. The dimensional model may be more useful in explaining the relationship of suicide attempts of different age of onset.