Visual hallucinations affect up to 75 percent of Parkinson's patients.

It causes them to see people and animals that aren't there, but now medication that targets these hallucinations is changing that.

Adrian Mireles was diagnosed with Parkinson's in his early 40s.

"What people don't understand, with Parkinson's, it affects a lot of you. People think, 'oh, it makes you shake.' The shaking is the least of your problems," Mireles said.

He struggled to follow conversations, and most unsettling of all, when he drove to work, he began seeing things like a bobcat on the road.

"And the first couple times, I slammed my brakes, you know, to not hit it, and then got there, and it wasn't there," Mireles said.

According to the Parkinson's Foundation, up to 70 percent of patients suffer hallucinations.

"Hallucinations can be present during the day, at night, and can be very disruptive for the day-to-day of these patients. There is always this risk of them losing contact with their reality," Movement Disorder Neurologist Juan Ramirez-Castaneda said.

The doctor prescribed an atypical anti-psychotic drug called Pimavanserin, trade name Nuplazid, which targets serotonin receptors.

"Activating these receptors can help tailor the psychosis or hyperactivity that happens in the brain," Ramirez-Castaneda said. 

It's the first antipsychotic that works on the neurotransmitter serotonin, and not dopamine, known to be a cause of Parkinson's.

Antipsychotics carry strong warning labels, and Parkinson's patients should always check with their doctors to see if the risks outweigh the benefits.