Doctors thought Andrew Carnegie, 12, of Edmonton in Alberta, Canada, was too young to have Parkinson’s disease.

But sure enough, Andrew, who suffered for two years with headaches, sweating and muscular difficulties, was diagnosed with Parkinsonism, which is caused by Parkinson’s disease, Canada.com reported Sunday.

But thanks to the drug Sinemet, which is often given to patients with the neurodegenerative disorder, Andrew is no longer like the “decrepit old man” his mother once described him as.

Before the medication, eating was a chore, as the muscles along the left side of his body cramped easily. He often lost his balance, so walking was not easy.

Parkinson’s disease is caused by the death of the cells that produce dopamine, a chemical that carries signals between the nerve and the brain. Usually the disease affects adults ages 65 and older, although a small percentage of its patients are under the age of 50.

"The average age is about 56," said Ray Williams, executive director of the Parkinson's Society of Alberta, which has been providing support to the Carnegies since Andrew's diagnosis. "But 11 years old, and he has Parkinsonism - that's the youngest one that we're certainly dealing with here, for sure."

Parkinsonism, also known as Parkinson's syndrome or atypical Parkinson's, is a neurological syndrome characterized by tremor, hypokinesia, rigidity, and postural instability

Now, Andrew takes Sinemet, a dopamine substitute, five times a day, and it’s as if he doesn’t even have the disease. His fingers aren’t cramping, he is walking to school again, playing his favorite game – Guitar Hero – and plans to take part in September’s Parkinson’s Society SuperWalk.

“It was like this miracle drug,” said Deidre Carnegie, Andrew’s mom.

Click here to read the full story from Canada.com.