Anxiety and depression: When should we intervene?

Written by: Dr Stephanie Thornton | Published:
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An estimated one in 10 teenagers have mental health problems and there is a high prevalence of anxiety and depression. In this five-article series, Dr Stephanie Thornton advises schools and teachers. In part three, she asks when are these conditions severe enough to warrant treatment or intervention

It is widely believed that anxiety and depression are increasingly common in our teenagers. Exactly how frequent these problems are in UK schools is hard to say: there has been no large-scale survey since 2004.

However, what we do know for sure is that at least 1 in 10 teenagers suffer some sort of mental health problem, and that the most common mental health problems are anxiety and depression (Beesdo et al, 2009), which may affect as many as one in six teenagers. Girls are more likely to suffer than boys (Craske et al, 2003).

And NHS figures show that 12.8 per cent – roughly one in eight – five to 19-year-olds had at least one mental health disorder when assessed in 2017. This figure rises to 16.9 per cent of 17 to 19-year-olds. Furthermore, of these, emotional disorders were the most common, affecting 8.1 per cent of five to 19-year-olds in 2017. And of these, anxiety-related disorders were the most common – 7.2 per cent (see SecEd, 2018a).

Depression and anxiety are intrinsically distressing. Beyond the immediate misery, these problems create a range of adverse developmental outcomes. School work is undermined, as are social relationships, and there is a markedly increased risk of substance abuse, self-harm, suicidal behaviour and other adverse developmental outcomes (Woodward & Fergusson, 2001). These mental health problems often become chronic, lasting not only through adolescence but through adult life (Gregory et al, 2007).

Anxiety and depression: A five-part series by Dr Stephanie Thornton

Part 1: Anxiety and depression: The new normal? March 2020:
Part 2: Anxiety and depression: Are they co-morbid? April 2020:
Part 3: Anxiety and depression: When should we intervene: May 2020:
Part 4: Anxiety and depression: Managing anxiety in the classroom: June 2020:
Part 5: Anxiety and depression: Managing depression in the classroom: July 2020:

As a consequence, finding effective interventions to reduce anxiety and depression in the teenage years is a priority for mental health services. But how can we address such widespread problems, and when should we try?

Anxiety and depression can be triggered in many different ways. All sorts of life events can be stressful, and stresses either at home or in school, or between peers – even reports of terrible events in the media (Whalley & Brewin, 2007) – may trigger anxiety and depression.

Intriguing new research that suggests that some individuals are far more vulnerable to such stressful life events than others (Lionetti et al, 2018): faced with the same stressors, Lionetti et al use plant analogies to illustrate how some survive, the way a dandelion survives in the least favourable circumstances, whereas others suffer, as a delicate orchid would suffer – and in between these extremes are the average “tulips”.

Orchids become anxious and depressed, dandelions breeze right on. Why these differences in sensitivity occur is not yet well understood. Is there a genetic component, or some learned strategy?

Anxiety and depression run in families: the children of anxious or depressed parents are more likely themselves to suffer these problems, suggesting the probability of both a genetic component, and also a contribution from parental role models and strategies.

But when should we intervene to treat anxiety and depression in the young? There are two issues here. First, how to identify when anxiety or depression constitute a problem worth treating. And then, when is the optimal moment to intervene?

Every normal human being will experience moments of worry, moments of sadness. Indeed, these reactions are often appropriate and even protective. A child who was never worried by any sort of challenge, never upset when sad things happen would be a cause for serious concern.

However, exactly where the borderline lies between normal, healthy worry or sadness, and a concerning anxiety or depression is very hard to define.

Obviously, a child or teenager whose anxiety or depression is disrupting ordinary life has a problem that is easy to identify as pathological and needing referral for expert intervention. But how many more who are presently managing their distress fairly effectively and so appear “okay” are actually damaged by anxiety or depression, and would benefit from supportive intervention?

Teenagers typically do not talk about these problems, and are often adept at hiding their feelings, so it is likely that many milder levels of suffering go unnoticed. Historically, it has been only the more severe levels of anxiety or depression that have led to referrals for treatment.

That is still often the case: CAMHS services are massively overstretched, reporting waiting lists of up to 18 months in some areas and research has shown that a quarter of referrals are rejected (see SecEd, 2018b). So referral to the mental health services for anything but the most serious problems may seem pointless.

As a result, the burden of both identifying who needs help with anxiety or depression and providing that help is falling increasingly on schools. This, despite the fact that expert opinion is increasingly arguing that the time to intervene in these problems is as early as possible – preferably before the problem starts getting out of hand, and certainly before it has become serious or chronic.

Mental health issues are often only identified in the teenage years. However, there is strong evidence that these problems have often begun much earlier, in childhood or even infancy (Kessler et al, 2007).

There has long been an argument that in an ideal world we would provide interventions to very young children who are at risk of such disorders, even before there are signs of the problem (Hirshfeld-Becker & Biederman, 2002).

But resources for such interventions are thin. Most “at-risk” infants and young children will not receive such support. And so, teenagers will continue to arrive in our schools with anxiety and depression of some degree.

Extrapolating from work with infants, many experts believe that the best time to offer interventions to counter anxiety and depression is before these things have got out of hand, and ideally, before they even arise. We certainly should not wait until a teenager is crippled by these feelings. No level of distress from these sources is too slight to justify supportive intervention. But what practical implications does this have, in our schools?

Every normal teenager will experience episodes of worry or sadness. The “dandelion” will cope better with this than the “orchid”. But how well either cope will depend, in part, on how effectively he or she has been taught to recognise these emotions and manage them, how much he or she has the self-confidence to cope.

Good parenting teaches these things. But many teenagers arrive in our schools having been offered no parental (or other) guidance in these matters. If we are genuinely committed to trying to reduce the burden of mental health problems in the young, there is a strong case for providing guidance and support in these areas to all of the young: nipping problems in the bud for some, offering useful advice to those already managing some degree of anxiety or depression – and advertising a welcoming, safe and confidential space for those with more severe issues to talk about their situation, and find support.

How formal should what we offer in schools in this context be? Some experts have advocated intervention programmes with a variety of structures, many including group cognitive behavoural therapy, delivered, for example, by teachers or school nurses. However, such relatively formal interventions are costly in time and resources, and of unclear benefit.

Initially, there seemed to be evidence that such interventions could be effective. However, a major meta-analysis of many studies (Caldwell et al, 2019) has recently concluded that many such studies had design faults, and that there is little evidence that school-based interventions of this kind offer much benefit.

Would lower key, less resource-demanding activities – even simple classroom discussions of strong emotions such as worry/anxiety and sadness/depression – be equally effective? We yet do not have the research to answer that question; it is surely worth exploring this possibility.

  • Dr Stephanie Thornton is a chartered psychologist and former lecturer in psychology and child development. To read Dr Thornton’s previous articles in SecEd, including in this series, go to

Further information & research

  • Beesdo, Knappe & Pine: Anxiety disorders in children and adolescents: developmental issues and implications for DSM-V, The Psychiatric Clinics of North America, 2009:
  • Caldwell et al: School based interventions to prevent anxiety and depression in children and young people: a systematic review, The Lancet Psychiatry, November 2019:
  • Craske: Origins of phobias and anxiety disorders: Why more women than men? Elsevier, 2003.
  • Gregory, Caspi, Moffitt et al: Juvenile mental health histories of adults with anxiety disorders, American Journal of Psychiatry, February 2007.
  • Hirshfeld-Becker & Biederman: Rationale and principles for early intervention with young children at risk for anxiety disorders, Clinical Child and Family Psychology Review, September, 2002.
  • Kessler et al: Age of onset of mental disorders: A review of recent literature, Current Opinion in Psychiatry, 2007:
  • Lionetti et al: Dandelions, tulips and orchids: Evidence for the existence of low-senstive, medium-sensitive and high-sensitive individuals, Nature, January 2018:
  • SecEd: One in eight students have a mental health disorder, official NHS figures confirm, November 2018a:
  • SecEd: A quarter of CAMHS referrals are rejected, October 2018b:
  • Whalley & Brewin: Mental health following terrorist attacks, British Journal of Psychiatry, February 2007.
  • Woodward & Fergusson: Life course outcomes of young people with anxiety disorders in adolescence, Journal of the American Academy of Child and Adolescent Psychiatry, September 2001.


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