For some reason, adjectives indicating mental instability have always been a key marker of difference between American and British English. We have crazy and insane; they have mad and daft. Does the New York Times article above indicate a meeting of the minds on mad, or merely that headline writers really like short words? Only time will tell.
Moving on to nouns, I’ve always felt the U.K. nutter is more expressive than our nut, and in recent years have wondered what U.K. visitors to Philadelphia (near which I live) think when they discover that it’s governed by a Mayor Nutter. Predictably, I enjoyed this quote from a recent Reuters article on the Murdoch scandals:
“We used to talk to career criminals all the time. They were our sources,” says another former reporter from the paper who also worked for Murdoch’s daily tabloid, the Sun. “It was a macho thing: ‘My contact is scummier than your contact.’ It was a case of: ‘Mine’s a murderer!’ On the plus side, we always had a resident pet nutter around in case anything went wrong.”
My pulse quickened some months ago when the PBS program “Frontline” posted Wikileaks leaker Bradley Manning’s Facebook status updates, including this from September 4, 2009: “Thinks Cambridge, Massachusetts is full of crazy (but fun) nutters.” But it turns out that Manning’s mother is from Wales and he spent much of his adolescence in that country.
However, I haven’t given up hope on the nutter front and was very pleased to read this yesterday in John Nichols’ blog at The Nation:
But it is becoming all too clear that the “right-wing nutter” fantasy that the debt-ceiling debate could be gamed for political points is crashing into the prospect of a “crunching global recession.”
So far, no sightings of daft.
notoneoffbritishisms.com 
Hi, I’m English and I just want to say that daft isn’t the same as mad/insane over here. Daft is more like silly; do americans have silly? Wacky, then? Also you could say daft to mean stupid or foolish, but the stupidity/foolishness would have to have been amusing in some way.
There are a lot of Nutters in East Lancashire in North West England. A Mrs Nutter lives behind my parents and one Alice Nutter was hanged as a witch in the 17th Century.
There are many more Nutters in Lancashire.
I have heard of Alice Nutter, and, from what I’ve read, her prophecies were nice and accurate.
Here is Philadelphia we have a real Nutter for mayor. (har, har)
Nut and nutter are not necessarily the same in BrE.
You can say ‘he’s a sports nut’ meaning he’s mad about sport, or you might say ‘he’s nutty about sport’ (that’s a bit old-fashioned though), but you wouldn’t say ‘he’s a sports nutter’. In a way, ‘nutter’ is quite a serious word, really only used when you think someone is actually disturbed. For example, if someone threatens you with violence in the queue at the Post Office, you’d say he was a ‘nutter’. In a British gangster film (if you can bear to watch one), you will find Ray Winstone approvingly calling someone a ‘nutter’ meaning he’s a borderline insane and probably actually enjoys killing people.
If someone said they were going to tight-rope-walk across Niagora Falls, you’d say he was nuts. Being a ‘nutter’ I think implies some fell intent. However, there’s probably quite a lot of variation in the use of these words in the UK.
To avoid any potential confusion I’d like to point out that “crazy” and “insane” are perfectly valid words in British English but they are more “official” or “standard” use, whereas “daft” and “mad” are colloquialisms.
‘Nut’ is often used as a verb in Scotland (and I think northern England) to mean ‘headbutt’, but only occurs in a few constructions.
A nutter is usually someone violent, fanatical or wont to cause trouble. That friend-of-a-friend who starts a fight outside of the pub, punches a policeman, and ends up in jail for the evening is a nutter. A person who owns a suspicious number of knives and a gas mask is a nutter. I suspect ‘psycho’ carries the same meaning in American English.
Can also be used, like any good British insult, in a friendly sense. Your mate who jumps out of planes for fun is a nutter; as is that guy you know who always tries to drink everyone else under the table.
I always got the impression that ‘nut’ in the U.S. leans more towards suggesting an eccentric (like a conspiracy theorist), or someone with a mental illness.
One point of interest: you almost never hear the word applied to women, unless we’re talking about a proper ‘bunny-boiler’.
Mad is still only angry here in Canada. Nutcase we use, nutter we don’t.
I use nutter, and have used nutcase, nutty, and nuts (English East Midlands).
I agree with ‘nut’ as a verb meaning ‘to headbutt’, it’s used here in Northants too; so nutting – ‘he thought about nutting him’ – and of course nutted – ‘he got nutted’. Nutting in the sense of ‘Here we go gathering nuts in May’ seems to be as dead as the activity.
Daft does not mean crazy or insane; more foolish, silly, empty headed, and so on. It’s gentle; calling someone a muppet (mentioned elsewhere on this site) is far stronger. Has anyone mentioned ‘daft as a brush’?
I seldom use daft. I asked a friend half my age, and he agrees with all the usages above.