30/01/2017 12:49 GMT | Updated 31/01/2018 05:12 GMT

From An Enlightenment King To Enlightened Princes: Mental illness And The Royal Family

Most people only know two things about George III. He lost us America and he went mad, although those with a degree in Advanced King George Studies might have heard that he wasn't actually mad, but suffering from a metabolic disorder called porphyria. A new BBC documentary, showcasing the Georgian Papers Programme, an academic partnership between Royal Archives and King's College London, made possible by personal permission of the Queen herself, challenges all this.

I shall stick to psychiatry, and leave "how we lost America" to others, except to say that there may be some Americans currently wondering if King George wasn't such a bad leader after all.

Making retrospective psychiatric diagnoses of historical figures is fraught with difficulty. There usually aren't medical notes, and even if there are, the meaning of the words used have usually changed over time. The disorders themselves may also have changed - psychiatric disorders are not set in stone, but complex amalgams of biology, society and culture. If these change, so can the disorder itself.

However, one advantage of being a monarch is that there is plenty of material to study, especially as now we can read the letters he wrote whilst ill and when well. Even then, caution is needed. The illness of a King was a delicate matter - one of his doctors resorted to hiding the unpalatable truth behind Latin even in his private diary, writing that "Rex noster insanit" - Our King is mad.

The most likely diagnosis is that he was suffering episodes of mania, a severe version of what we now label "bipolar disorder". The over excitement, pressure of speech, sexual disinhibition, excessive disorganised activity, sleep problems and so on are characteristic. Contemporary students are taught to look out for grandiose delusions - such as believing one is, or is related to royalty, as another feature of mania. This doesn't work so well when the patient is a genuine King, but the records give plenty of other evidence of delusional thinking common in mania.

But what about the porphyria? Everyone who has seen "The Madness of George III", with the King so brilliantly played on stage and screen by Nigel Hawthorne, will remember that the film concludes by informing the audience that the King wasn't mad at all, but had a rare metabolic disorder that only looked like madness. The script suggests that the pompous doctors, played as comic turns, overlooked this, and it was only his servants who noted that the King's urine returned to its normal colour as his mind returned - a classic sign of an episode of porphyria.

It was two psychiatrists, the mother and son team of Ida MacAlpine and Richard Hunter, who first proposed this diagnosis in 1968. True, there were symptoms that might have suggested porphyria, a genetic disorder which has been found in some members of the Royal Houses of Europe. But later critics highlighted serious mistakes and inconsistencies in the sources, and that mania was more likely. The question resurfaced ten years ago in the Lancet. Scientists analysed a lock of the King's hair, hoping this would prove that he had genetic evidence of porphyria, but this remained unresolved because they couldn't extract any DNA.

So why did the theory of porphyria gain such traction over the years? MacAlpine and Hunter were disillusioned. They were fed up with psycho analysis, and instead believed that most mental disorders were caused by either known (such as porphyria) or as yet unknown organic physical conditions. Diagnosing an organic metabolic disorder in one of the most famous "madmen" in history would be a wake up call to modern psychiatry, and also remove the stigma or taint of mental illness from the Royal Family.

Are there any lessons here for modern psychiatry? MacAlpine and Hunter's wish to remove the stigma associated with mental illness remains a noble cause. But instead of directly combating that stigma, their preferred method was to say that he wasn't really mad at all, but had an organic and hence legitimate disorder. They were probably mistaken in their preferred diagnosis, but that misses the point. It is wrong to go looking into the urine, even if Royal, solely to prove that this is a real disorder, as opposed to unreal mental illness. There is nothing wrong with devoting one's career, as many of my colleagues do, to using neuroscience to better understand bipolar disorder, and to develop better treatments. And I am pleased to say things have moved on since poor King George was over dosed with emetic tartar whose only result was that when a lock of his hair was analysed in 2005 it contained seriously toxic levels of arsenic, the chief constituent of the "medication". But we do not need good science to know that bipolar disorder is a real and serious illness, which, irrespective of the results of the research, cannot be abolished with the stroke of a pen as MacAlpine and Hunter tried.

Now let's fast forward to King George's descendants to see how much times have changed. On Wednesday I hosted a private dinner at the Royal College of Psychiatrists attended by Prince Harry on how we can improve the mental health of our current serving and ex serving personnel. These things are off record, but I can say that his passion and commitment to making things better was extraordinary, and impressed even the old lags like me around the table. The Heads Together campaign which the younger Royals lead is directly challenging the old assumptions that there is a hierarchy of illness, in which physical illness is placed above mental illness. King George would have approved.

Professor Sir Simon Wessely, Regius Chair of Psychiatry, King's College London and President of the Royal College of Psychiatrists

George III - The Genius of the Mad King is being shown at 21.00, Monday Jan 30th on BBC 2