Emmerdale star John Middleton has said filming his dementia scenes has been like "watching someone diminish".
Fans have watched his alter-ego vicar Ashley Thomas suffer from vascular dementia.
Next Tuesday, ITV is screening an entire, groundbreaking episode through the character's eyes.
The 63-year-old actor told The Sun: "It's watching someone diminish.
"Every aspect of this story is true and has come directly from someone we've spoken to who has experienced it."
He added: "It's an everyday story that most people don't see because it's hidden. We want to portray something people can identify with and think to themselves, 'We're not alone'."
Charlotte Bellamy, who plays his long-term love Laurel, 42, told the newspaper: "You're watching a character who has been in the show for 20 years and you feel like you know him so well, so to watch him deteriorate is very emotional. It's like it is in real life."
Next week's special has been filmed from Ashley's viewpoint and is billed as "an exceptionally moving piece of drama".