"She could well have been almost Tourette's, where she would just shout things out," Janis, 60, told People in an interview to promote her book, Loving Amy: A Mother's Story. "We just do not know."
It was when she was looking back through the numerous notebooks Amy kept, filled with writings, song lyrics and obsessive lists, that Janis wondered if her daughter may have suffered from the neurological disorder, which is characterised by physical and vocal tics.
"She was a singer, a superstar, an addict and a young woman who hurtled towards an untimely death. To me, though, she is simply Amy. She was my daughter and my friend, and she will be with me forever," Janis writes.
Amy's problems began in childhood, Janis revealed. At the age of 9 she had a "lattice of scars on her arms" from cutting herself. At 10 she was caught shoplifting and pierced her lip in the back of a classroom. By 12 years old she was smoking in the garden and three years later downing Southern Comfort and lemonade.
When Amy's parents divorced her problems at school escalated — Janis says she became more "unmanageable, loud, intimidating and a bully."
"I knew in my heart that Amy was angel and devil rolled into one," says Janis. "Loving Amy became a relentless cycle of thinking I would lose her, then not losing her, waiting to lose her."
Janis also reveals that she and Amy would hold hands until Amy left home at 18 and that her daughter continued to call her Mummy for the rest of her life.
On Amy's battles with addiction, Janis says drugs eventually defined her. At one point, after refusing to go to rehab, Amy began a home detox — by lighting up a crack pipe. She embarked upon a two-day binge of alcohol and drugs, cut her arms and her face, put out a cigarette on her cheek and punched a mirror, causing serious cuts to her hand.
Drugs and alcohol ravaged Amy's body. She had a tooth missing, the bones were sticking out of her knees, she suffered from seizures, had an underactive thyroid, emphysema from smoking a crack pipe and hadn't had a period for several years.
But even when she was at her lowest point, Janis and her ex-husband Mitch Winehouse were unable to take the step of "sectioning" their daughter under the Mental Health Act (keeping her in a hospital against her will).
A few months before she died Amy was drinking 30 times more than the safe limit, was still suffering from bulimia and eating little more than scrambled eggs (which were easy to purge).
On July 23, 2011 Amy Winehouse died alone at the age of 27, face down in her bed in her Camden home — having fallen off the wagon after weeks of sobriety.
Loving Amy: A Mother's Story is available to preorder from Amazon.co.uk.
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