Behavioural problems (BPs), such as stealing, fighting, and temper tantrums, are common across childhood and there is increasing evidence that they can impact on multiple adverse outcomes in adulthood including poor well-being, criminal behaviour, and unemployment. However, there is little evidence regarding possible explanations for the strong associations observed. Additionally, less is known about the long-term consequences of BPs in low- and middle-income countries.

I will test three competing explanations for the associations observed between childhood BPs and adverse outcomes in adulthood (including mental health problems, criminal behaviour, and unemployment) using:
1) A UK population-based dataset (ALSPAC).
2) A dataset in a middle-income country (Brazil) with high levels of BPs and violent crime (1993 Pelotas birth cohort).

Hypothesised explanations include: i) exposure to ongoing adversity across the life-course (e.g. financial hardship, exposure to crime, family instability); ii) shared genetic and early-life environmental risk factors (e.g. childhood adversity, impaired cognitive and emotional processing); iii) potential “snares” (e.g. the consequences of BPs, such as substance use, curtailed education or gang membership, that may trap young people into experiencing persisting problems). Clarifying pathways is important as different explanations would have different clinical implications, specifically when and what to target. For example, evidence supporting ‘potential snares’ highlights the importance of either treating childhood BPs directly or targeting the ‘snares’. In contrast, evidence supporting ‘ongoing adversity’ points to targeting the stressors experienced across the life-course.