Mark Salter is a consultant psychiatrist based in London’s East End, specialising in risk, untowardness and media portrayals of mental distress. Here, he outlines the five key systems for human emotion and explains why bipolar disorder is but a construct that helps us make sense of Stephen Fry television programmes.

Does bipolar disorder exist?

An interesting thing happened to me six or seven years ago. I made a television programme with Stephen Fry called The Secret Life of the Manic Depressive. I invited him to my psychiatric hospital and showed him around, and over the two or three days we were filming I got to know him. I was struck that this man was making a programme about his own experiences of suffering from a mood disorder, and while he was using the term bipolar disorder to describe himself, I was using it to describe my patients who have lives so unimaginably different from Stephen Fry’s it was hard to believe they’ve got the same thing. It's interesting, though, the idea of mood and mood disorder and that someone like Stephen Fry and some of my patients who've spent their lives in psychiatric hospitals can have the same condition.

Should we consider that the two conditions are separate because they’re different in severity?

Let’s look at it another way. Let’s take poisonous animals. Let’s say we want to classify not disturbances of mood but our relationship with an animal. Is there any value or use in distinguishing between bees and hornets? Yes, because the hornet sting will cause swelling and possible death, whereas the bee will leave you with a nasty sting. But what about an ant – a tiny little bite from an ant? These things can all cause harm in varying degrees, and as you classify what happens when you’re bit by a bee or a hornet or an ant or a snake or any other creature, knowing something about it is very helpful if it can allow us to make meaningful decisions about how best to deal with it.

If it’s a bee sting, rub it and it will go away. If it’s an adder, it will feel unpleasant but as long as you’re not old or young you’ll get over it in a day or two without medical intervention. If it’s a purple octopus, however, you’ve got problems. Knowing what the problem is allows you to do something about it.

Similarly, when the brain or the mind go wrong, or the body goes wrong, knowing what the diagnosis is allows you to do something about it. For example, if you’re a heavy smoker and you’ve got asthma, I’ll tell you not to smoke. My knowledge as an expert of what happens in the lung is very valuable in that it allows me to make an intervention which can, as a result, make you better.

But what about when things get complicated? And we’re not talking about a jellyfish or an adder or a lung or anything – we’re talking about the human mind. And what is the mind? The mind is a function of the brain. Can we recognise patterns in the way that the brain goes wrong? Can we tell a mental adder from a mental rattlesnake? Can we identify and reliably classify mental, for want of a better word, diseases in such a way as to make interventions? Or are there other factors that come into the equation that make mental diagnoses harder, if not impossible, compared to physical diagnoses?

Do you have an idea of what mood is?

Definitely, but I have an even clearer idea of what mood isn’t. It’s very interesting if you speak to people, particularly in western civilisation, they have this fascinating idea that mood is a wild, dark irrational thing. Notice how in our culture we pride people on their ability to be rational. To say you’re “cool, calm and collected” is a compliment. But the truth is that to say someone is cool, calm and collected is to say they are exactly that. It’s not because they are intellectual or rational, but rather that we value them because they have control over their emotion.

If we define emotion, we define it as something reactive: it’s beyond your conscious control, it’s as much to do with your body as your mind. Notice that if I have an idea, I point to my head. If I have a feeling, I point to my chest or my stomach. I say I’m green with envy, my heart is in my throat, I’m boiling with rage. Our language reflects the total somatic, bodily quality of emotion. So whatever the search for emotion is, it has to start in our bodies as much as our minds, as well as in our language.

If you want to know what emotion really means, the words we give to our emotions (joy, love, happiness, sadness and so on) are detours: they’re red herrings in the search for what emotion truly means. That’s not my phrase but neuroscientist Joseph LeDoux’s. We deceive ourselves when we try to think of emotion as being about love, hate and so on. The truth is those are just fancy words that the linguistic part of our brain, which is very non-emotional, does to sooth ourselves in to the idea of it being a false certainty.

So there’s no actual division between emotions?

No. We can categorise emotion usefully, and we can do it anatomically. We like to think of emotion as being something we have a lot of – mania for example, or sadness – in contrast to feeling flat. But if you look at the brain we have different systems, and those systems will tell us that we’ve got fear, anger, sadness, joy or disgust. Anger, joy, fear, sadness and disgust is the main vocabulary of the five key emotions. So it’s not a spectrum, it’s not a bipolar thing. Bipolar is an artificial construct, something we need to make sense of Stephen Fry programmes.

There’s only one positive emotion in there – what impact do you think that makes on human life?

That’s an interesting point. You might alloy contentment. You might also say anger is a positive emotion if it’s doing what it’s intended to, which is to stop other people eating your babies.

It doesn’t make you feel positive though, does it?

No, it’s unpleasant at the time because it’s associated with intent over arousal. If you look at a person who’s angry and a person who’s delighted and both are standing at the arrivals gate of Heathrow airport, the physiology of both people are the same. It’s just the name you give to it, and the context in which it occurs.

But you said they were different areas of the brain.

They are indeed. But the overall physiology is driven by those different areas of the brain, and sometimes they’re the same and sometimes tantalisingly different.

It’s a very good point that joy is a positive emotion. But is it really? People who are deliriously cheerful tend to make very bad decisions. Being sad increases caution, it improves the quality of judgements.

But is there a point in making good judgements that don’t lead to happiness. Is a sad, long-lived life necessarily better than a short happy one?

I’d leave that to the individual to decide. A good or a bad thing is an externally imposed value judgement. Socrates said the unexamined life wasn’t worth living. If you do examine it you often end up being quite frightened or a bit depressed by what you might find. So maybe depression is a bit better for us than we might think.