I have a friend whose second decade on this planet was defined entirely by anorexia nervosa. She spent her secondary school years in various in-patient units over in the USA. She is now in her thirties and pretty much recovered, but she requires ongoing support from time to time.

She went to see a psychiatrist here in London last week who told her: “I can see anorexia is far behind you. I don’t even have to put you on the scale.”

For a person with medical qualifications to have so little idea about what defines an eating disorder and what it is appropriate to say to someone with a history of mental illness defies belief. For, whilst my friend technically has a “healthy” body mass index, eating disorders happen in the mind. They cannot always be seen.

Why trying to spot mental illness is tricky

Over break I had lunch with my cousin, who works with children with autism and is one of the cleverest and most intuitive people I know. After I left college, while I was in the throes of my own eating disorder, I stayed with her for about six months.

“I didn’t know,” she told me. “You hid it so well. I knew something was wrong with you emotionally, but I wouldn’t have guessed it was bulimia.”

That’s the problem with trying to “symptom spot” mental illnesses using physical criteria. Self-harm is the same - the harming of oneself physically is a symptom, the cause lives in the mind. Furthermore, self-harm isn’t, contrary to popular belief, restricted to cutting: a recent investigation by the BBC found that an increasing number of young women were “self-poisoning” by, amongst other things, drinking huge quantities of alcohol with the intention of causing themselves physical damage.

One of the questions I am most commonly asked by parents and teachers is: “Where is the line between common-or-garden teenage angst and a mental health issue?” What they want to know is, “When should I start worrying?” That’s an incredibly difficult question to answer, because it can differ from person to person - after all, our mental health happens in the context of our unique circumstances and personality.

Thick skin or resentment?

Mental health is getting a lot of media attention at the moment, so I suppose a sort of backlash was inevitable (even if it does make my skin crawl because of the transparent lack of any kind of compassion, humanity or common sense). The newest generation of teenagers are being called snowflakes, spoiled and over-protected.

There are non-believers of mental health who will say, “I was bullied and it never did me any harm.” Such attitudes reveal the speaker to be someone who believes people in emotional distress are “faking it” and will one day be grateful for the adversity. These attitudes are also, I believe, often motivated by resentment caused by the misguided belief that today’s young people “have it better”.

Saying that, “One day you’ll look back on this time when you were slashing your thigh to ribbons, were bullied daily about your disability or you despised the sight of yourself, and be grateful that it helped you develop a thick skin,” isn’t a terribly useful argument either for young people enduring mental illness, or the teachers and parents who look after them.

Catch it early and head-on

The only sure-fire way to spot mental health issues when they are in their embryonic stages (and are therefore eminently more curable) is to make it acceptable and normal for everyone to talk about how they feel. Distress is a completely normal and healthy emotion (particularly, I might add, when the subject at hand is something as emotive as rape) and we shouldn’t shy away from allowing young people to express it.

If we exorcise our emotions at the time we feel them, we can move on. If we are told our behavior is “attention-seeking”, that we should think about people who have “real” problems or, worse still, that showing vulnerability makes us “feeble”, we will push our feelings to one side. However, emotions, like all energy, can never be destroyed. Ignoring them doesn’t make them go away. Instead, they fester and become toxic, until one day our stress bucket overflows.

There are early symptoms of mental illness and they include low self-esteem, dramatic mood changes, behaving in an anti-social way and obsessively comparing oneself with others. You’ll note, however, that this list also sounds a lot like “being a teenager” and I suppose that is also a valid critique of naysayers who don’t take teenaged mental health seriously.

The problem with this mindset that “teens will be teens” is how adults seem to get amnesia on their 21st birthday, forgetting what it was like to be a child or teenager and to experience these things first-hand. I, conversely, cannot help but reflect on how great it would have been if the full spectrum of human emotion had been normalized when I was young, so that I didn’t come to associate “strength” with stoicism and consequently develop the anxiety disorder I still struggle with today.

Often, the only true way to know if someone has a mental illness is to create an environment where they can tell you how they feel without fear of judgment. 

Natasha Devon is the former government mental health champion for schools in the UK and founder of the Body Gossip education program and the Self-Esteem Team. She tweets as @NatashaDevonMBE