The NHS's drug watchdog has rejected an appeal from campaigners and charities to widen access to certain Alzheimer's drugs.
John lost his ability to make a cup tea when he came off the drug
The National Institute for health and Clinical Excellence said the drugs should not be used to treat early stage disease, as campaigners wanted.
When Valerie's husband John - now 77 - started developing memory problems, doctors decided he could benefit from one of the disputed drugs, Aricept (donepezil).
In February this year, after two years on the medication, doctors suggested John take part in a trial of a newer drug, which it was hoped might reverse rather than slow the decline of his condition.
But when he stopped taking Aricept, his wife saw a rapid deterioration.
"In just a couple of weeks after coming off the drug, he absolutely fell to pieces.
"He had been able to do most things; make a cup of tea, dress himself.
"But he was totally dependent within the fortnight.
"He couldn't dress himself, he started to wander and to fall. He didn't even know where our bedroom was."
The couple, who live in Surrey, decided that John would not take part in the research and should go back on to Aricept.
"We had had two years of a really happy and good life on it.
"It had slowed his decline. I felt I still had my husband.
"When he went back on it, he picked up and was back to about 95% of where he was before he came off the drug.
"He could find his way around the house again, and I could leave him alone again while I went to the shops."
Valerie, 69, said she was grateful John had been able to get Aricept when his disease was at an early stage.
"It was so effective in his case
"It seems so unfair that won't be the case for people now. I don't understand it.
"These drugs can transform two people's lives - the patient's and their carer's."