Ina Lewis, 73, had been initially admitted to Denbighshire's Glan Clwyd Hospital after being found wandering on Colwyn Bay promenade.
She was then transferred to The Priory in Bristol, 200 miles away.
Health officials said sometimes they had to provide care outside north Wales when care beds were unavailable.
But Mrs Lewis's son has criticised the decision, and said his mother had been taken on an "eight-day magical mystery tour" of hospitals.
"One of the main things about dementia is to keep everything the same, and familiar for the patients," said Stephen Lewis.
"What they've ended up doing is 100% what they're not supposed to do.
"It just seems to me there are not enough beds at all, and I don't think we're being given the full picture about just how bad the beds situation is at the three north Wales hospitals."
Mrs Lewis was originally admitted to the emergency unit at Glan Clwyd on 8 May.
A decision was then taken to transfer her to another hospital three days later.
"They said she was going to be transferred to either Bangor or Wrexham hospitals - either one would have been fine. But, lo and behold, she was transferred to Bristol on the Wednesday," said Mr Lewis.
"They didn't even tell us which hospital they'd taken her to. We had to ring round to find where she was, and discovered they'd actually taken her to The Priory in Bristol."
Three days later she was brought back to north Wales, and finally on Monday was transferred to the Bryn Hesketh Hospital nearer her home in Colwyn Bay.
A Betsi Cadwaladr University Health Board spokesman said: "Although we cannot comment on this specific case, it is sometimes necessary to arrange for patients needing specialist care to be admitted to units that are outside of the local area if an appropriate bed is not currently available within north Wales."
The family of a dementia patient say they cannot believe their mother was sent from north Wales to a private clinic four hours away.