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Introduction: Numerous life, peer, and school-related factors have been found to be associated with non-suicidal self-injury (NSSI) among adolescents; however, most studies have not explored the possible reciprocal nature of these associations. The aim of the current study was to examine bidirectional and longitudinal associations between NSSI and several life, peer, and school-related factors (i.e., stressful life events, peer relationships, academic achievement, and attitudes towards school). Method: Community-based adolescents completed questionnaires assessing the variables of interest at three time points; age 12 (T1; 55.09% girls), age 13 (T2; 56.95% girls), and ages 14-15 (T3; 57.41% girls). In total, 529 adolescents provided complete data across all three-time points. Results: Analyses showed a bidirectional association between NSSI and both attitudes towards school and stressful life events. Speciically, stressful life events at T2 predicted engagement in NSSI at T3, and NSSI at T2 predicted increased risk of stressful life events at T3. Similarly, having negative attitudes towards school predicted NSSI at T2, which, in turn, predicted negative attitudes towards school at T3. Further, academic achievement at T1 was negatively associated with NSSI at T2. Peer relationships were neither a predictor nor a consequence of NSSI. Conclusions: Our results suggest that NSSI can be both a predictor and a consequence of various life, and school factors. Focus on these factors in prevention and intervention efforts for NSSI among adolescents may be warranted.

The cognitive predictors of mathematical abilities and disabilities/disorders (MD) were investigated. An overview is given of the prediction by early numeracy skills such as Piagetian logical thinking, counting, and number comparison skills. In addition, studies of relationships between language and numeracy in kindergarten and grade 1 are discussed. Moreover, the chapter sought out to extend our knowledge regarding the relationship between motor, visual and visuomotor skills and mathematical abilities and disabilities. Furthermore, the chapter discusses studies of working memory, inhibition, naming speed and inference control as cognitive predictors for mathematical abilities and MD. Finally findings about the sensitivity of number sense for MD are provided.

This paper presents an overview of two studies in which the co-morbidity of clinical disorders in mathematical learning disabilities (MLD) in elementary school children has been examined. MLD were reported in children with different levels of intelligence. About 54% did not meet the discrepancy-criterion. The proportions of reading (32%), spelling (21%), visuo-spatial (11%) and language disabilities (10%) were higher than that found in the general population. The proportion of ADHD (42%) was also higher than that found in the general proportion. Comorbid heterotypic depression and anxiety rates were 8% and 6% respectively. Furthermore a proportion of motor problems (15%) and ODD problems (5%) were reported. This study indicates that co-morbidity with clinical disorders is more a rule than exception in children with MLD. In addition, there may be different patterns of symptoms between genders. Girls more often had an averageintelligent but non-discrepant intelligence profile with less co-morbid problems.