Conversation:

I'm not sure if this term is used outside of Ireland. When someone is "up to high doh" then then they are completely stressed or frazzled.

Also in Scotland, esp. Glasgow: George McDonald Fraser cites it as part of the lexicon of the mainly Glaswegian Gordon Highlanders he commanded shortly after WW2 (1946-47).

Interesting! It goes to show again that there's little new under the sun.

Thanks AgProv.