Jacob and Pete James have had their roles reversed. The 11-year-old now helps his 60-year-old father, who lives with dementia.

Flame-haired and freckle-faced, Jacob James is a ball of energy. One moment he's standing next to you, the next he's shooting hoops or rolling down the sloped lawn in his family's garden, gathering flecks of dry grass on his school uniform.

"He's certainly not shy. Do you want to take him?" his dad Pete jokes.

The signs of dementia emerged three years ago when Pete began to forget things. He was diagnosed with younger onset dementia late last year.

"It's just a tiny bit different," Jacob says.

"The way I think about and the way I feel about Dad will never change. He'll always be my dad. He'll always be there to give me hugs and kisses."

Younger onset dementia is a less common form of brain disorder that affects about 26,000 Australians under the age of 65. Some have been diagnosed as early as their 30s.

"All the stuff I used to be able to do without thinking, now I've got to get help," Pete says. "Keep smiling. That's about all you can do."

Taking one step at a time. Jacob James with his mother Cathy, older brothers Josh and Ben and his father Pete, who lives with dementia. ( ABC Life: Jason Om )

The James family lives on Sydney's outskirts, where the suburbs give way to paddocks and the flood-prone banks of the Hawkesbury River.

Pete is a draftsman by trade and, thanks to an understanding employer, continues to work.

He's married to Cathy James who, along with the rest of the family, has thrown herself into charity work to raise awareness around dementia.

"We've been together for 33 years. When I see him walk in a room I still get butterflies," Cathy says.

"I always make sure I give him a hug, tell him we love him and that everything will be okay. Because at the end of the day, nothing is ever, ever that bad that it is worth him being upset."

Gentle reminders get them through the day

Cathy says the way her son Jacob soothes his dad's frustrations "blows her away". ( ABC Life: Jason Om )

Daily routines now require more attention.

"It's one step at a time," Cathy says. "We've just got to do one thing, have that finished and do the next. It's no use talking about what's happening tomorrow or what's happening in an hour. It's just what's happening now."

Advice from Dementia Australia's executive director Susan McCarthy: Maintain intimacy and connection. "A person with dementia may not recall exactly what happened but they still have feelings. Intimacy, touch and relationships are really important," Ms McCarthy says.

"A person with dementia may not recall exactly what happened but they still have feelings. Intimacy, touch and relationships are really important," Ms McCarthy says. Continue meaningful activities. "Maintain what connected you before. For example, walking on the beach or sitting on the couch holding hands."

"Maintain what connected you before. For example, walking on the beach or sitting on the couch holding hands." Seek support if you need it. "You're not alone. Reach out for support because people can help you understand and come up with strategies."

"You're not alone. Reach out for support because people can help you understand and come up with strategies." Talk to the National Dementia Helpline 1800 100 500

Pete's reminders begin in the morning.

Jacob organises his dad's breakfast and the family lunches for the day. He makes sure Pete remembers to go to work before 8 o'clock. At the end of the day, he helps out with dinner and sets the table.

"Jake has always been a really old soul," says Cathy. "He has a way of making us feel extremely special. Giving us cuddles when we need it. He just seems to be able to cheer us up at the right time."

Jacob has become a soothing antidote to his dad's small frustrations. The wrong cup of tea is not a big deal. They can just make another one.

"He's having to say now, to his own dad, 'Dad, it's okay. Don't worry about it'. Some days it blows me away how a little boy can do that," Cathy says.

It's been a rapid adjustment for Jacob, who initially found his dad's diagnosis difficult to accept.

"I used to get cranky with Dad because he was forgetting everything," he says. "I had no idea about dementia at all.

"When I finally figured it out I was like, 'I'm so sorry Dad for all the times I yelled at you'."

Jacob has learnt to be patient when he's out with his dad. Walking down the street. At the dentist. At the shops.

"If he goes to say something again, I'll just nudge him on the shoulder and say, 'You already said this'."

Music creates a meaningful connection

Jacob says his love for his dad won't change. ( ABC Life: Jason Om )

Jacob loves music from the decades before he was born, having grown up with his dad's favourite songs.

Both of them listen to tracks from the '70s, '80s and '90s (on a Bluetooth speaker shaped like the poo emoji) in Jacob's bedroom.

"Pink Floyd, Skyhooks, Eagles, Guns N' Roses, ACDC. It's the best music ever," Jacob says, sitting on a cherry red shagpile rug.

Among stuffed and plastic toys, they enjoy a ritual that links Pete to the past. It's also the type of meaningful activity dementia advocates encourage families to do to maintain intimacy and connection.

Their favourite song is Sweet Dreams by the Eurythmics.

Jacob sings to his dad: "Everybody's looking for something…"

"I'm looking for a cure for dementia," he says. "So that Dad nor anyone else will have to go through this."

"Jacob's an amazing young man," Pete says. "He's my crutch, for want of a better term. If I get lost, if I lose my phone, if I lose my keys, he's always there."

"We don't know the answer some days," Cathy says. "But we're always together. Each day is extremely precious."

Some days it's sitting on the couch and cuddling. And for her family, she says, that's enough.

Jacob's thank you letter to his father

Jacob says his dad Pete "will always be his best mate". ( ABC Life: Jason Om )

As part of our video series on gratitude, Thanks, Jacob chose to write a letter to his dad. Here it is in full:

Dad, today we are doing a story for the ABC, and part of the story is me being able to thank you for being my dad, my best mate.

I know I tell you every day how much I love you and how much you mean to me. But today I want to say an extra big thank you for all that you have taught me and are still teaching me as we take each day one step at a time.

Dad, thank you for making me me, for the love of music we share, which means so much more to me now as it's our special time to chill and just hang out together.

One of our favourites… "Sweet dreams are made of these, who am I to disagree, travel the world and the seven seas, everybody's looking for something". Looking for a cure for dementia, Dad, so that you nor anyone else will have to go through this.

Our passion for the Sydney Swans sitting on the lounge cheering for the red and the white (a bit louder cheering coming from your side of the lounge). For teaching me how to ride a push bike, how to kick a soccer ball. I love the time we have at the park kicking to each other, and of course your horrible dad jokes that always makes me laugh watching you laugh at your own joke.

Dad, I'm watching you change daily and seeing you so upset, upsets me too. I always promise to give you lots of big hugs anytime you need one and to let you know I'm there for you.

Our roles are now just swapping sooner than we thought. But I'm here to help you now be your rock, like you have been to me. You are teaching me to have patience, understanding, and a good sense of humour. I love seeing you smile.

I'm learning, Dad, that no matter how many times you may ask me the same question, I will always keep giving you the same answer and not say 'I've told you that'. Please know you never have to say sorry to me as there is nothing to say sorry for.

You can do anything just in your own way now, and that's okay with me. When I'm with you nothing else matters. I love you, Dad.