Two sisters with close mid-Norfolk ties are joining a mass ascent of Ben Nevis this weekend as a touching memorial to their father and with a mission to help other families to cope with dementia.

Sally Mortimer and Suzanne Horobin watched with increasing dismay as their dad, Eddie Livock, a former painter and decorator from Mattishall, suffered the effects of Pick's disease, a progressive destruction of nerve cells in the brain. He died in 2007, aged 66.

On Saturday, they will join more than 80 other walkers on a challenge to scale the 1,344m (4,409ft) Scottish peak to raise money for the Alzheimer's Society. The group had together already totted up nearly �45,000 in sponsorship, said Sally, 38.

Mr Lovick had worked for Norwich-based Building Services (Easton). As the illness took hold, it changed the behaviour of the 'wonderful' father the sisters knew and loved.

Sally, who lives now in Cheshire and works for Waitrose, said: 'Suzanne and I are doing it because we want to stop anyone going through what we went through as a family. Dad would have been 70 next Wednesday, and we want to raise money to continue the society's work.'

Six years ago, Sally raised just over �5,000 by going on the Inca Trail in South America. Her 40-year-old sister, who lives in Rutland and works for the National Health Service, has run half-marathons in aid of the cause. Their mother Margaret, who still lives at Mattishall, does voluntary work for the Alzheimer's charity.

Sally and Suzanne hope people who knew them during their time at Neatherd High School, Dereham, or who remember their dad will add to their personal fundraising efforts.

To sponsor Sally visit www.justgiving.com/sally-mortimer; to add to Suzanne's sponsorship, visit www.justgiving.com/suzanne-Horobin0