Carly Simon has Parkinson's disease.

The 83-year-old singer has explained she stepped out of the spotlight in recent years because of her condition - a degenerative brain disease that can impact on movement - and also due to feeling self-conscious after having skin cancer removed from her face, though she insisted that doesn't mean she has "stopped living".

She said in a lengthy statement: "So many people have written to me, kindly wondering about my relative silence, asking how I am and what I have been doing. The truth is, I've been learning how to live with Parkinson's disease.

"It has taken me some time to understand the diagnosis, to adjust to it, and to decide how much I wanted to say about it publicly. Parkinson's is different for everyone, and it can be unpredictable. Some days I'm so tired I can't get the day moving at all. On others, it gives me a little more room to move, think, work, and feel like myself...

"I was also treated for basal cell carcinoma on my face. The cancer was removed, but the surgery affected my appearance and made me more self-conscious about being seen in public. I have always been more critical of my appearance than anyone else could possibly imagine (check out the irony of having written You're So Vain.), and this gave my inner critic quite a lot of new material.

"Between my mobility issues, the Parkinson's diagnosis, the surgery, and the emotional effects of it all, withdrawing from public view was the most palatable reaction. If a person is allowed to hibernate during both winter and summer, then I have become an all-season bear.

"But I have not stopped living, and I have not stopped working."

The Your So Vain singer initially thought her struggles with walking were an "unfortunate and rather ironic part of the recovery process" after having both knee and one hip joint replaced due to arthritis, but as her condition began to deteriorate, she sought medical advice from the prestitious Mayo Clinic.

She said: "I had trouble standing up from low chairs and deep couches without someone offering me an arm. Overstuffed furniture became my enemy. Once seated, I could feel as though I had been swallowed by the chair and might remain there permanently, like a guest who had badly overstayed her welcome.

"Eventually, there were periods when I could not walk without considerable help. My family and I knew that something more was going on. After an extensive evaluation at the Mayo Clinic, I was diagnosed with Parkinson's."

While Carly noted most people are aware of the physical impact of Parkinson's disease, it has also caused her problems in other ways.

She said: "I began treatment, including taking medication to help with stiffness and other symptoms. There is no tidy or predictable schedule to the illness. It does not consult my calendar before deciding what kind of day I am going to have.

"Parkinson's is usually associated with movement, tremors, and balance, but it can affect much more than the body. It can bring anxiety, depression, exhaustion, and apathy. The apathy is particularly strange. You can find yourself lying there like a starfish drying in the sun, arms pointing in all directions, while nothing inside is telling you to get up, read, watch, write, sing, call someone, or do much of anything at all.

"That has been one of the hardest things to explain. It is not simply sadness or laziness. It is as though the part of the brain that sends out invitations to participate in life has temporarily misplaced the guest list."

The Nobody Does It Better hitmaker - who has Sally, 52, and Ben, 49, with her first husband, musicianJames Taylor - is preparing to release her first full-length original album since 2008 and she's grateful the record, Comes in Waves, gave her purpose at such a difficult time.

She said: "In the middle of all this, I began recording a new album, Comes in Waves. That still feels mysterious to me. Music has always known when to arrive. It has rescued me more times that I can count. It is like a cat or dog that quietly appears beside you when it senses you are not quite yourself.

"The album includes songs and fragments of songs that had been waiting for me, some for years. There were melodies, verses, and ideas written down and tucked away for some unknown future when I would have the time and attention to finish them.

"Apparently, that future is now.

"Working on the music gave shape to days that did not always have much shape. It gave me somewhere to go without having to leave the room. It reminded me that illness can change your life without becoming the whole of your life.

"I do not consider Parkinson's a gift or a blessing. It is neither. It is difficult, frustrating, and sometimes frightening. I am still learning how to live with it and how to accept it without feeling that I have surrendered something essential.

"I am still writing, singing, imagining, laughing, worrying, remembering, and occasionally getting trapped in an overstuffed chair."