Burden of bullying: enduring effects of early victimisation on depression in adulthood

What is already known on this topic?

Depression is one of the most common mental health problems, the risk for which is particularly high during adolescence. Adolescent depression tends to rebound, and preventing the development of depression is preferred over treatment.1 To reduce the risk for depression early-on, factors predisposing to its development must be understood. Bowes and colleagues deal with this important topic and assesses the impact of victimisation on depression.

Peer relationships play an important developmental role, and adolescents spend a majority of their time with peers.2 In adolescents thus, the effects of peer difficulties on mental-health outcomes are likely to be high. It is known that victimisation is associated with the risk for anxious-depressed symptoms, low self-esteem and loneliness.3 Most studies, however, have examined the concurrent effects of victimisation on depression and it remains to be seen if victimisation affects mental health in adulthood.4 Bowes and colleagues’ study is a commendable attempt in this direction and examines effects of early adolescent victimisation on depression in young adulthood.

Methods of the study

This study is based on the well-known Avon Longitudinal Study of Parents and Children cohort (a UK community based birth cohort—http://www.alspac.bris.ac.uk) and follows 6719 participants from age 13 to 18 years. Peer victimisation was assessed at age 13 years with self-reports on the ‘modified bullying and friendship interview schedule’, and included measures of both overt and relational victimisation. A three-level ordinal variable for victimisation (none, occasional, frequent) was created to assess if differences in intensity of victimisation had an effect on depression. Assessments of depressive symptoms at age 18 years were made with the ‘clinical interview schedule’ (according to International Classification of Diseases (ICD) 10 criteria). In addition, participants were asked to report on feelings of sadness and loss of interest in the preceding weeks, months and years. Logistic regressions were used to analyse the effect of victimisation on depressive outcomes. Depression and bullying behaviours at age 13 years as well as a number of family-related factors (parental education and occupational levels, parental depression and history of childhood maltreatment) were included in the analytical models as covariates.

What does this paper add?

• Peer victimisation at early adolescence was associated with a high risk for onset and persistence of depression at adulthood, irrespective of a past or parental history of depression (OR 2.58, 95% CI 1.81 to 3.67).

• A notable aspect of this study was the inclusion—in the analyses—of several confounding variables that influence both victimisation and depression. Despite controlling for confounders, a strong association was found between early adolescent victimisation and later-life depression (OR 2.32, 95% CI 1.49 to 3.63). About one-third of all young adults with depression had faced peer victimisation in early adolescence. This shows that effects of victimisation on depression are particularly tenacious.

• Another important finding to emerge was that the frequency of victimisation moderated the risk for depression. Frequently victimised adolescents showed an almost twice greater risk for depression than those not victimised (OR 1.87, 95% CI 1.29 to 2.72).

Limitations

• ICD-10 was used to assess depressive symptoms, which, as opposed to the Diagnostic and Statistical Manual of Mental Disorders (DSM), does not consider irritability as a core diagnostic criterion. As irritability is a common occurrence among depressed adolescents, the use of ICD-10 may have underestimated depressive symptomatology in the sample.

• Self-reports, which were used to assess victimisation and bullying, provide poor estimates of bullying perpetration.

• Poor peer networks, friendship difficulties, low self-esteem and emotion regulation problems increase the risk for victimisation as well as depression. Effects of these factors were not taken into account while assessing the victimisation–depression relationship.

What next in research?

• The risk for depression is high among victimised adolescents, but not all victims develop depression. Future research can determine factors that facilitate/impede the development of depression in victimised individuals—genetic variations, environmental stressors and complex interactions between these two factors may induce resilience or susceptibility to the depressogenic effects of victimisation.

• Boys and girls differ in the coping strategies used against victimisation. It would be interesting to assess if processes leading from victimisation to depression also show sex differences.

Do these results change your practices and why?

These results are important in clinical practice for the following reasons. First, early detection of victimisation is important to prevent adulthood depression and its associated health burdens. Second, the risk for victimisation is known to be high among children and adolescents with pre-existing physical/mental health problems. The consequent development of depression in this group may further impair prognosis. Thus, adolescents with pre-existing health problems may need extra attention towards averting victimisation in adolescence.