A dementia sufferer's son said the disease "strips someone of their character", as Jeremy Hunt called on Britain to "raise our game" on the illness.
Pauline Murray-White's son filmed his mother's battle with the illness since she was first diagnosed in 2007 and captured the moment she struggled to recognise a picture of her late partner.
James Murray-White said the relationships of sufferers "eventually shatter."
He added: "Dementia just strips someone of their character, their personality, who they and what they knew."
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The Sherlock actor made the comment while he received an award for his humanitarian work.