I was interested as well so went looking. He is probably referencing this. It was the first article I could find on it. You have to read below the fold to get a decent sense of what happened. A key paragraph is included below. https://www.bbc.com/news/world-europe-49660525

"After being diagnosed with Alzheimer's four years before she died, the patient wrote a statement saying that she wanted to be euthanized before entering a care home - but that she wanted to decide when the time was right.

Before she was taken into care, a doctor decided that assisted suicide should be administered based on her prior statement. This was confirmed by two separate doctors independently and a date was set.

When the day came to end the woman's life, a sedative was put in her coffee and she lost consciousness.

But the woman then woke up and had to be held down by her daughter and husband while the process was finished."

I spent about 10 seconds googling for you: https://www.bbc.com/news/world-europe-49660525