Genetic and Environmental Causes of Variation in Trait Resilience in Young People

The aim of this multi-informant twin study was to determine the relative role of genetic and environmental factors in explaining variation in trait resilience in adolescents. Participants were consenting families (N = 2,638 twins in 1,394 families), from seven national cohorts (age 12–18 years, both sexes) of monozygotic and dizygotic twins reared together. Questionnaire data on the adolescents’ Ego-resilience (ER89) was collected from mothers, fathers and twins, and analysed by means of multivariate genetic modelling. Variance in trait resilience was best represented in an ADE common pathways model with sex limitation. Variance in the latent psychometric resilience factor was largely explained by additive genetic factors (77% in boys, 70% in girls), with the remaining variance (23 and 30%) attributable to non-shared environmental factors. Additive genetic sources explained more than 50% of the informant specific variation in mothers and fathers scores. In twins, additive and non-additive genetic factors together explained 40% and non-shared environmental factor the remaining 60% of variation. In the mothers’ scores, the additive genetic effect was larger for boys than for girls. The non-additive genetic factor found in the twins’ self ratings was larger in boys than in girls. The remaining sex differences in the specific factors were small. Trait resilience is largely genetically determined. Estimates based on several informants rather than single informants approaches are recommended

Associations between delusion proneness and personality structure in non-clinical participants: Comparison between young and elderly samples

Background: Few studies have explored the prevalence of delusions in the non-clinical, elderly population. In addition, the association between personality structure and delusions remains poorly investigated. The aims of the present study were, first, to explore the relation between age and the prevalence of delusion proneness and, second, to examine the association between personality and delusion proneness in young and elderly participants. Sampling and Methods: A sample of young (n = 343; aged 18-30 years) and elderly (n = 183; aged 60-75 years) non-clinical participants completed the 21-item version of the Peters et al. Delusions Inventory (PDI-21), an elaborated and validated version of the Launay-Slade Hallucinations Scale, and the revised version of the NEO Personality Inventory (NEO-PI-R). Results: Mean scores on the PDI-21 for the young and elderly participants were compared. An independent t test revealed that the total mean scores were significantly higher for young participants compared to elderly participants. PDI-21 items were then re-grouped into previously validated factors. Independent t tests revealed that young participants had significantly higher scores for items related to suspiciousness and persecutory ideas, thought disturbances and jealousy, grandiose ideas, paranormal beliefs and apocalyptic ideas. In contrast, elderly participants scored significantly higher than young participants on the religious ideation factor. Associations between scores on the NEO-PI-R and the PDI-21 were then examined for the two groups. For the young sample, correlational analyses revealed a significant relationship between the total score on the PDI-21 and scores on the openness, neuroticism and agreeability facets of the NEO-PI-R. For the elderly sample, correlational analyses revealed a significant relationship between the total score on the PDI-21 and the openness facet of the NEO-PI-R. Discussion: Results from the study reveal that delusional ideation is a relatively common experience for both young and elderly non-clinical participants. In addition, findings are in line with studies suggesting that neuroticism and aspects related to neuroticism increase the risk for the development of psychotic symptoms such as delusions. However, it is important to mention that, because the present study includes non-clinical subjects and is a cross-sectional study, more research is needed. Copyright (c) 2006 S. Karger AG, Basel