"We are all walking around with a life-ordeath system in our heads,” says Professor Tim Dalgleish, describing the affective system of emotions and moods – the way we feel – that has evolved with humans over millions of years.

“Feeling is enormously potent, so the question is, why do we have it? Why don’t we just solve problems in our lives using the fantastic, cognitive part of the brain?”

The answer, he says, is that the affective system is almost like a survival signal. “It’s telling you, far quicker than we can rationalise, how good you are at the business of staying alive.”

And as the inaugural Dawson Professor of Young People’s Mental Health, Dalgleish knows just how important that is to tackling the current sharp increase in mental health diagnoses, particularly among younger age groups.

It’s a challenge that shouldn’t be underestimated: the number of young people in the UK with a mental health condition has risen from one in eight in 2017 to one in five today. There are fundamental principles to be addressed. When considering what’s necessary for survival, for instance, we’d likely list such essentials as water, food, shelter, protection from danger and access to mates.

But as Dalgleish says, these are more easily achieved in a social group than in isolation – and easier still, the higher your status within that group. “In evolutionary terms, the pressure is not: ‘How good can I get at finding water?’ It’s: ‘How good am I at affiliating with others?’ And: ‘How good am I at maintaining the highest possible social status given my capabilities?’

The affective system can act as a signal that those things are going wrong.” Falling status, or failure to affiliate with others, puts you at risk of being ostracised from the group – which for most of human existence would be a death sentence.

Why do these very ancient pressures affect the young people Dalgleish works with today, who range from University of Cambridge students to children as young as three treated in the Cambridgeshire and Peterborough NHS district for PTSD, anxiety and other mood disorders? It’s because, he says, our affective system is completely mismatched to the 21st century, where most things are not matters of life and death.

“You might be working with a young person who’s not been invited to a party. In evolutionary terms, that’s signalling your affiliation and social status is in danger, which previously could have had life or death consequences.

But in 21st-century terms, you simply didn’t get to go to the party.” The point is that it feels just the same. “I believe there’s a considerable amount of mental health distress that comes from carrying around a very ancient system in the modern world, as we experience challenges that press the same life-or-death buttons, even though they’re no longer dangerous.”

Coverage of the rising incidence of reported mental health problems in the UK, especially in the young, is generally coupled with speculation about whether those problems are being overdiagnosed.

Last December, then Health Secretary Wes Streeting launched an independent review into rising demand for mental health, ADHD and autism services in England. Earlier that year, Streeting had told one interviewer that “definitely there’s an overdiagnosis.”

But the rise in diagnosis is complex, says Dalgleish. It does include overmedicalisation, and some people seeking diagnosis privately despite, in reality, being below the clinical threshold. But more straightforwardly, there’s also increased awareness.

“When I was at school in the 1970s there was supposedly no one who was LGBTQ, or with mental health problems, or with autism or ADHD. We know now that just can’t have been true.”

Critically, randomised epidemiological studies suggest formal diagnosis is, if anything, below the true level of occurrence in the population. 

Dalgleish’s job – now turbocharged by his new post based at St Catharine’s and the Department of Psychology – is to ensure this rising need is met. Doing that will require innovation.

“The clinical interventions we’ve got now have almost reached the limit of their capacity,” he says.

“So we need a paradigm shift to move things forward. And the untapped wealth of knowledge from discovery science – the analysis of large-scale experimental data – seems to me the most fruitful thing to leverage.”

This involves translating and applying research insights, not only to develop new interventions and preventions, but also to improve existing interventions.

“That’s my priority,” he says. “Joining these two worlds together.”

There are three principal ways of approaching this, says Dalgleish.

“The first is to use discovery science to identify some mechanisms you think are really important, then try and build an intervention around them.

The second is to take an existing clinical intervention that works for some, but not all, people back into the lab, and what’s not so good – then refine the intervention based on those insights and take it back into the clinic.

Thirdly, there’s reverse translation, when a complicated existing intervention is analysed for active ingredients and then a new intervention is built focused on those effective elements.”

Dalgleish currently oversees examples of all three approaches, including research on how we use memory for emotional information – specifically, how we remember upsetting things that have happened to us.

“Discovery science work found that the way upsetting memories are remembered is really quite different in people with mental health problems compared to those without,” he says.

“This has led to the development of a simple intervention that flexibly trains people to selectively remember positive things, over and over again.”

Another approach has guided work on cognitive therapy for post-traumatic stress disorders, which can severely disrupt the schooling, education and social life of young people. Here, the exposure therapy model used in adults – pioneered in the 1980s treating service personnel who had returned from the Vietnam War – was deemed not fit for purpose for young people, because they haven’t yet consolidated the adult belief that everything is going to be OK.

Therefore, the whole cognitive behavioural therapy intervention was refined, and is now in the NICE (National Institute for Health and Care Excellence) guidance as the treatment of choice for PTSD in young people.

A new trial is underway with three to six-year-olds, where rather than providing verbal therapy, clay, drawing and toys are used. Finally, for reverse translation, Dalgleish’s team have investigated why mindfulness interventions that work really well for adults don’t work at all for people of school age.

The result, after a lot of lab work and due diligence, was an entirely new intervention that trains young people to ‘decentre’ – to step back and see the bigger picture.

Crucially, all three of these new or reformulated interventions make use of technologies that meet young people where they are: YouTube videos, Spotify podcasts, texts, WhatsApp exchanges or 10-minute video calls with therapists.

“These are much more appealing to young people,” says Dalgleish, “because it’s little and often.”