''It is very frustrating for her. It's hard for her to be let down by her memory. It's hard for us to watch as well,'' son Simon Holst said yesterday.
''But to see her out of the kitchen, it makes me the saddest. I never thought I'd see that.''
Dunedin born and raised, Dame Alison (77), New Zealand's first celebrity chef, officially hung up her apron last year and her final column ran in her local Orewa newspaper last month.
She first appeared on television screens in 1965, and has since written more than 100 recipe books aimed at everyday cooking for Kiwis.
Mr Holst, who has been working alongside his mother for the past 20 years, said it was a difficult time for the family as the illness took hold.
''Dementia is nothing to be ashamed of or embarrassed about,'' he said.
''But it's hard watching someone you love slipping away, watching her world shrinking. She can't do some of the things she used to do. You know, she was such a great traveller.''
Dame Alison was being looked after at home in Orewa by her husband, Peter, and Mr Holst said his dad was doing an ''impressive job''.
''There are good days and bad days. We are trying to avoid situations that get her confused, things like deadlines,'' he said.
''She is happy most of the time. Alison is still Alison but just slightly different.''
Mr Holst said he had been humbled by the support since it was made public yesterday that his mother was ill.
''We have had some lovely messages. And I ... know she would be grateful for those messages.''
He said being named among New Zealand's most trusted people had been an honour for Dame Alison. She loved being involved in people's lives and felt fortunate to have been able to spend 50 years pursuing her passion for cooking.
''She likes to think she helped people,'' he said.
Prolific career
• Dame Alison has published more than 100 books, defining her ''everyday cooking'', selling more than 3 million copies.
• Her career began as a home science lecturer at the University of Otago.
• She first appeared on television screens in 1965, a few months after the introduction of television to New Zealand.
• In 2011, she was made a Dame Companion of the New Zealand Order of Merit.
