Image copyright Cormac Neeson Image caption Cormac Neeson with Dabhog, who is now five

The Northern Irish rock musician Cormac Neeson says having a child with Down's syndrome has changed his life in a "joyful and positive" way.

In 2014 Neeson was, in many ways, living the rock 'n' roll dream. His band, The Answer, had sold hundreds of thousands of records and had toured the globe with the likes of The Rolling Stones, The Who and AC/DC.

But the singer's world was shaken to the core when his wife, Louise, gave birth to a very premature baby at just 27 weeks.

"It was an unbelievably dark and troubled time," says Neeson.

Their son, Dabhog, was born weighing just 1lb 12ozs (0.8 kg) and was immediately taken into intensive care. He stayed in hospital in Belfast for the next four months.

"For a large portion of that time we weren't sure on a daily basis whether he was going to make it through," Neeson adds.

Two weeks into that time they had to deal with the news that Dabhog had Down's syndrome - a genetic condition that typically affects a person's learning abilities.

"That was something else that just added to the whole very intense experience."

Image copyright Cormac Neeson Image caption Dabhog underwent heart surgery aged one

Around that time The Answer were releasing an album.

"I would have to take myself away from the incubator for 20 or 30 minutes and do interviews to promote the album.

"I had to pretty much pretend I was in a place where I was comfortable releasing good time rock 'n' roll music. It was a complete collision course with where my head was actually at," Neeson says.

Dabhog did survive and was discharged from hospital, although he had to have surgery aged one to fix a hole in his heart.

The experiences have had a profound effect on Neeson's outlook on life and his music.

"Whenever the dust settled and Dabhog was home and his health started to turn and life settled down a bit I realised that creatively I was not in a place where I could genuinely write the kind of music we had spent the last 10 years writing," he says.

He went to Nashville where he worked with American songwriters and musicians to put together a new album. "The result was really a collection of songs that was so introspective and intense and so truthful that they really could only be part of a solo project.

"It's a world away from the stuff that I had spent my career making up till that point."

Image copyright Helena Neeson Image caption The title of Neeson's solo album, White Feather, came from an event during his wife's pregnancy

One of the songs, Broken Wing, is a tribute to Dabhog.

"It's a good opportunity to talk about Down's syndrome and normalise what Down's syndrome is, but also to celebrate my son for being the individual that he is," Neeson says.

He says he wanted to get over in the song that raising a child with a learning disability has a unique set of challenges, but "it's unique in a really great and powerful way".

Neeson says he also wrote the song to help new parents of children with Down's syndrome.

"I was kind of placing myself back in the hospital whenever we were told that Dabhog had Down's syndrome and I was thinking that if I'd heard this song back then I might have taken some comfort from it.

"If your child has Down's syndrome that is not what defines your child. Your child is unique and amazing like every other child. I've never met a person like my son, Dabhog.

"The joy that he brings into our lives is something that I could not have anticipated when we were just worrying day to day about his health and getting him out of that hospital alive."

Image copyright Cormac Neeson Image caption Neeson has chromosome 21 tattooed on his arm. The most common form of Down's syndrome is Trisomy 21, when there are three copies of that chromosome instead of two

The album's title, White Feather, is a reference to an incident early in Louise's pregnancy with Dabhog.

At around three weeks they were told it was as an ectopic pregnancy, when a fertilised egg is implanted outside the womb, often in a fallopian tube. The egg cannot then develop into a baby and the pregnancy has to be terminated due to the risk to the mother's health.

After taking Louise into surgery the doctors realised it was not an ectopic pregnancy, but said they would have to wait another two weeks before being able to scan for a heartbeat and confirm if the baby was still alive.

The night before the scan, Neeson went for a walk by himself in the hills near his hometown of Newcastle, County Down.

"A lot of soul searching went on. I said out loud, 'I need a sign'. At that point I was stopped dead in my tracks."

He had spotted a white feather in the trees. "In Ireland a white feather represents life," Neeson says.

The next day the scan revealed a "gigantic" heartbeat.

Image copyright Shona Cutt Image caption Neeson's band The Answer have released six studio albums

Dabhog is now five and in September started school, where Neeson says he has made friends and won certificates for being pupil of the week.

"Just to be able to experience our little boy thriving like that and being so communicative and being such a life-affirming character and for him to bring so much joy into our lives, it's a massively positive experience for us and we're thankful for that," Neeson says.

Dabhog now has a younger brother and Neeson has become an ambassador for the learning disability charity Mencap in Northern Ireland. Dabhog attended a Mencap centre in Belfast for specialist learning and early intervention support.

"Before my wife became pregnant with Dabhog I suppose my sole focus in life was essentially myself and I think you become much less selfish when you have a child," he says.

Looking back to 2014, he adds: "There are moments in your life when you don't know how you're going to get past these obstacles that are set, but you do.

"Whenever you come out the other side there's a real sense of victory and that's where we are at now."

Follow us on Facebook, or on Twitter @BBCNewsEnts. If you have a story suggestion email entertainment.news@bbc.co.uk.