Child mental health is at the forefront of current UK government policy, and awareness of the impact of childhood depression is booming, and rightly so.

Depression is the leading contributor to the global burden of disease in young people aged 25 and under (Gore et al., 2011). Although rare during early childhood, the prevalence of depression rises steeply throughout adolescence and into adulthood (Vizard et al., 2018). We know that adolescent depression is highly impairing and is associated with poor functioning in school, family and social contexts. Onset of depression during childhood or adolescence is associated with greater impairment in a range of domains compared to adult-onset disorder (Zisook et al., 2007).

Previous studies have shown that adolescent depression increases the risk of depression and suicidal ideation in later life (Copeland et al., 2013; Fergusson et al., 2005). This study aimed to systematically review the evidence for the odds of depression, anxiety and suicidality (suicide thoughts and/or attempts) during adulthood (aged 21 years and older), following depression in adolescence (aged 10-19 years).

Methods

The paper did not provide a link to a study protocol, but I did find a record of it on PROSPERO, which is a database of systematic review protocols.

Inclusion criteria

Studies were eligible if they met the following criteria:

• Involved a community sample
• Participants were screened for depression during adolescence (ages 10-19) using a validated measure and based on criteria in the Diagnostic and Statistical Manual of Mental Disorders (DSM)
• Psychopathology (depression, anxiety and/or suicidality) was re-assessed in adulthood (≥21 years)

Analysis

The researchers made appropriate use of synthesis methods by using meta-analysis where it was considered reasonable to do so, e.g. where studies investigated similar outcomes and used unique cohorts. Results that could not be combined in meta-analyses were described narratively.

Risk of bias

The researchers assessed the risk of bias of the included studies using the Newcastle Ottawa Scale, which is a tool commonly used for assessing the quality of observational studies. Two researchers independently conducted risk of bias assessment and discrepancies between reviewers were addressed, with third party consultation sought if necessary.

Characteristics of included studies

Twenty articles from 15 different cohorts were included in the review. Sample sizes ranged from 128 to 15,563 participants. Studies were conducted in Canada, Finland, New Zealand, Sweden and the United States. Adolescents were aged between 11-19 years, and adult depression, anxiety and suicidality were assessed between the ages of 21-35. Follow-up periods ranged from 4 to 20 years. Studies used either structured diagnostic interviews or rating scales to assess depression, anxiety and suicidality. The authors report that there was no difference in the strength of results for studies that used diagnostic interviews versus rating scales. The overall prevalence of depression at baseline (i.e. during adolescence) ranged from 5.6% to 44.0%. It is worth noting that this range is greater than the estimated worldwide prevalence of depression in adolescents (2.6% – (Polanczyk et al., 2015)).

Results

Depression

• Eighteen articles reported on the association between adolescent depression and adult depression. All but one found a positive and statistically significant relationship.
• Eleven studies were included in a meta-analysis, which produced a pooled odds ratio of 2.78 (95% confidence interval 1.97 to 3.93).
• This suggests that the odds of depression in adulthood is nearly three times greater for individuals who experienced depression during adolescence.

Anxiety

• Eight articles reported the relationship between adolescent depression and adult anxiety.
• No meta-analysis was performed due to heterogeneity, i.e. the studies were not considered to be similar enough for it to make sense to pool the results statistically.
• Overall, studies reported positive and statistically significant relationships between adolescent depression and adult anxiety. Odds ratios ranged from 1.4 to 8.14, with a lower confidence bound of 1.20 and an upper bound of 15.59.
• Only one study did not find a significant association for anxiety overall, but that study did report an association for social anxiety specifically.
• The authors of the systematic review have not reported results for any other individual anxiety disorders, so we do not know if the studies included in the review reported this.

Suicidality (thoughts and/or attempts)

• Five articles reported the association between adolescent depression and adult suicidality. Three reported both suicidal thoughts and attempts; one reported only attempts; and the fifth pooled thoughts and attempts into one measure.
• Meta-analysis was not performed due to variation in the ways in which outcomes were assessed, so results were discussed narratively instead.
• Three studies showed statistically significant associations between adolescent depression and adult suicide attempts.
• Two studies found evidence for an association between adolescent depression and adult suicidal thoughts.

Conclusions

Johnson and colleagues conclude that:

• There is strong evidence that adolescent depression increases the risk for depression in adulthood.
• There is also evidence that adolescent depression increases the risk of adult anxiety disorders.
• The evidence in relation to adult suicidality is less clear. The authors caution that since suicidal thoughts and attempts are rare outcomes, sample sizes were too small to reliably detect an association.

Strengths and limitations

Strengths

• The study used rigorous systematic review methods to reduce bias and therefore increase confidence in the robustness of the findings.
• Studies had to assess depression, anxiety and suicidality using diagnostic interviews or validated scales.
• The review only included studies carried out in general community samples, leading to greater generalisability of findings.

Limitations

• The authors highlight that the extent to which included studies controlled for confounding was variable, and often poorly reported.
• The level of heterogeneity between studies meant that meta-analysis was not possible in many cases, and limited the researchers’ ability to synthesise the evidence. Heterogeneity also prevented any investigation of subgroup effects.
• Studies included in this systematic review assessed adult outcomes between the ages of 21-35, so it can’t tell us anything about how adolescent depression affects mental health beyond the age of 35.
• Most studies reported the outcome of any anxiety disorder, so we can’t break down relationships for individual anxiety disorders. The one study that did do this found a relationship only for social anxiety, so it is possible that adolescent depression increases the risk of some types of anxiety but not others.

Implications for practice

These findings provide support for the hypothesis that depression during adolescence increases the risk of poor emotional health during adulthood. This is particularly concerning given that adolescent depression appears to be on the rise (Vizard et al., 2018), and highlights the importance of early identification and intervention for adolescent depression. Such intervention may not only reduce immediate distress and impairment for the young person, but may also improve their mental health outcomes in later life.

Conflicts of interest

None.

Links

Primary paper

Johnson D, Dupuis G, Piche J, Clayborne Z & Colman I. (2018). Adult mental health outcomes of adolescent depression: A systematic review. Depression and Anxiety. [PubMed abstract]

Other references

Copeland WE, Adair CE, Smetanin P, Stiff D, Briante C, Colman I, Fergusson D, Horwood J, Poulton R, Costello E & Angold A (2013). Diagnostic transitions from childhood to adolescence to early adulthood. Journal of Child Psychology and Psychiatry, 54, 791-9. https://doi.org/10.1111/jcpp.12062

Fergusson DM, Horwood L, Ridder EM & Beautrais AL. (2005). Subthreshold depression in adolescence and mental health outcomes in adulthood. Archives of General Psychiatry, 62, 66-72. https://doi.org/10.1001/archpsyc.62.1.66

Gore FM, Bloem PJN, Patton GC, Ferguson J, Joseph V, Coffey C, Sawyer SM & Mathers CD. (2011). Global burden of disease in young people aged 10-24 years: a systematic analysis. The Lancet, 377, 2093-2102. https://doi.org/10.1016/S0140-6736(11)60512-6

Polanczyk GV, Salum GA, Sugaya LS, Caye A & Rohde LA. (2015). Annual Research Review: A meta analysis of the worldwide prevalence of mental disorders in children and adolescents. Journal of Child Psychology and Psychiatry, 56, 345-365. https://doi.org/10.1111/jcpp.12381

Vizard T, Pearce N, Davis J, Sadler K, Ford T, Goodman A, Goodman R & McManus S. (2018). Mental Health of Children and Young People in England, 2017: Emotional disorders. Mental Health of Children and Young People in England, 2017. Health and Social Care Information Centre; NHS Digital. Available at: https://digital.nhs.uk/data-and-information/publications/statistical/mental-health-of-children-and-young-people-in-england/2017/2017

Zisook S, Lesser I, Stewart JW, Wisniewski SR, Balasubramani GK, Fava M, Gilmer WS, Dresselhaus TR, Thase ME, Nierenberg AA, Trivedi MH & Rush AJ. (2007). Effect of age at onset on the course of major depressive disorder. American Journal of Psychiatry, 164, 1539-46. https://doi.org/10.1176/appi.ajp.2007.06101757

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