Jay Leno is thankful his wife hasn't forgotten him.

The 75-year-old broadcaster was granted conservatorship over his spouse Mavis, 29, last year after she was diagnosed with advanced dementia - which causes a decline in thinking, memory, and reasoning skills - and while caring for her can be tough, he still enjoys their time together.

Speaking on Today, Jay said: "I understand what it is, so you can't blame someone...

"She's not forgetting me. That hasn't happened yet. She seems extremely comfortable now. And she seems happy, and she seems contented. It's actually okay. It's good. I enjoy taking care of her...

"I enjoy her company, like if I'm working on a car, she'd sit over there with a book and read.

"It was just very -- well, it still is, very comfortable. Before she had this, I would always go home after the Tonight Show, cook dinner for her, and we'd watch TV. The only difference is now you just can't really talk about a lot of things...

"You know, I can see the smile. I can tell when she's happy. And when she looks at me and smiles and says she loves me, I mean, I melt."

The "toughest part" of Mavis' condition was her repeated realisation that her mother had passed away because she could never remember being told the news before.

He said: "Probably the toughest part was every day she'd wake up and realise someone had called today to tell her her mother had passed away. And her mother died every day for, like, three years.

"Not just crying, I mean, you're learning for the first time. And that was really tricky. Yeah, that makes it hard."

The former Tonight Show host loves to dance with his wife.

He said: "You know, when I'm carrying her -- you know, carry her, like, to the bathroom -- we do this and I call it Jay and Mavis at the prom, you know, in high school, you know. So, we're just, like, back and forth. And she thinks that's funny."

Jay noted Mavis will often "point to something and say something that doesn't quite make sense" but he just offers her reassurance.

He said: "I'll go, 'No, it's good, honey. It's all right.' I sense she wants to be reassured that everything's okay.

"Now she really needs me and I like that. And I can tell she appreciates it. The idea that you get married, you take these vows, nobody ever thinks they'll be called upon to act on them. You know that part -- for better or worse. Even the worse isn't that bad."