Different Drummer LINDA RONSTADT’s cocaine use during the 1970s may  have caused the Parkinson’s disease that’s taken away her ability to sing!

A medical expert tells The ENQUIRER that heavy use of the drug dramatically increases the risk of developing the disease – and 67-year-old Linda has admitted that she once snorted cocaine regularly.

A study conducted by Dr. Deborah Mash, a neuro­scientist at the University of Miami who has not treated Ronstadt, revealed that the brain tissue of cocaine addicts contained abnormal amounts of a protein that is “a classic hallmark of Parkinson’s.”

Dr. Mash told The ENQUIRER: “We also found that cocaine abuse increased dopamine-stimulated neurons. Dopamine overload damages the cells much like Parkinson’s disease. That’s why more and more younger people are developing  Parkinson’s disease and Parkinson’s-like symptoms.”

Linda – an 11-time Grammy winner famous for the rock ballads “You’re No Good” and “When Will I Be Loved” – told “Rolling Stone” magazine in 1975 that her nose was cauterized twice due to her heavy cocaine use, and that she’d tried heroin, marijuana and methedrine (speed).

Meanwhile, Linda said that she probably suffered from Parkinson’s unknowingly for more than eight years, and attributed her symp­toms to a tick-borne disease.

“I was struggling to sing for so many years,” she confessed. “I knew there was something dramatically, systematically wrong.”

ACCORDING to the Mayo Clinic, several other issues may be determining factors in the onset of Parkinson’s including genetic predisposition as well as environmental conditions.

As The ENQUIRER has reported, Linda – who last sang publicly in 2009 – recently reached out to fellow Parkinson’s sufferer Michael J. Fox for advice.

But a pal said: “If Linda could go back in time, she’d never have started doing drugs.

“Now, it may be too late.”