We all know that politicians believe their own myth, but it's only recently that scientists have been able to prove it (and publish their results). All that posturing, narcissism and limelight-hogging is now considered a psychiatric disorder worthy of recognition. Hubris Syndrome is not necessarily something we're born with but, like a fatty diet, it quickly bloats us. The theory is that the closer we get to power, the more our brain starts to feed on it. Soon, we're like heroin addicts, needing ever more of it or we fall apart. Symptoms include: seeing the world as an ersatz stage on which to exercise power; a messianic manner; excessive belief in one's own talent; and feeling accountable only to God (so why worry what shareholders or voters think?). Sufferers can be impulsive, restless, reckless and isolated from friends. The syndrome is most dangerous where checks and balances are few. A sceptical spouse or confident friends can curb tendencies, but the more severe the affliction, the less does one seek other opinions. By making it a fully fledged medical disorder, psychiatrists hope to protect the world from power-crazy politicians like President Sarkozy. But hubris can double as charm. It's not until they're ordering rose petals to be cast in front of them as they walk that we realise we screwed up.