Jan. 29 update: Famed environmental activist Erin Brokovich met resistance as her team tried to test the area around an upstate New York school for clues to a case involving more than a dozen teens plagued by mysterious Tourette's-like symptoms and seizures.

At the request of local parents, Brokovich sent a team to LeRoy High School Saturday to investigate possible environmental causes for the  illness that has caused a group of girls to develop tics and involuntary verbal outbursts. One neurologist who has seen most of the affected girls has diagnosed their illness as psychological in origin, but some parents and members of the community have disputed that diagnosis.

The State Health Department has tested the school and ruled out environmental factors. But Brockovich plans to do more testing near the school in LeRoy, N.Y.

Brockovich told USA TODAY Friday that she is looking into a 1970 train accident that spilled cyanide and an industrial solvent called trichloroethene close to the site of the school.

Bob Bowcock, a member of Brokovich's team, came to LeRoy from California, NBC News reported. 

Bowcock looked at ground water and soil at a nearby park for anything out of the ordinary. "I'm just looking at the environment. I'm trying to see where things drain to. What types of soils they are," Bowcock told NBC News.

However, the school placed locks on all the entrances to the sports field, NBC's Rochester, NY, station reported Saturday. Local police and a school security guard initially refused to allow the Brokovich crew on school grounds until the school superintendent and a district spokesman arrived. Officials agreed to let parents, Bowcock and his team walk the grounds, without media, as long as they didn't take any samples.

Originally published Jan. 26: The mystery surrounding the strange illness that has struck a group of teenage girls in upstate New York deepened this week as more teens developed the same Tourette’s-like symptoms.

Dr. Laszlo Mechtler, the neurologist who has seen and is treating 10 of the 12 girls originally struck by the puzzling illness, told NBC’s Amy Robach that more girls had recently reached out to him.

One of those girls, Chelsey Dummars, told Robach how those symptoms have changed her life.

“I was doing things,” Dummars said, her words punctuated by tics and grunts. “I was going places a lot before this happened. Now I don’t feel like even going to stores because I feel like people look at me and judge me.”

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Dummars said she’s now being home-schooled because she doesn’t want to go out in public with her symptoms.

Like many of the parents of the affected girls, Dummars’s dad is distraught.

“To see her sit there and be broken to tears because she can’t handle it anymore … it rips your heart out,” said Dave Watson.

The mystery illness surfaced several months ago when 12 girls who had been attending the Le Roy high school began to display tics and involuntary verbal outbursts. Both the state and the local school district did extensive testing of the school grounds to see if there might be any signs of an infectious disease or some toxin the girls might have come in contact with. All those tests came back negative.

Mechtler has diagnosed the girls as having a rare condition called mass psychogenic illness, more familiarly known as mass hysteria. It doesn’t mean that their symptoms aren’t real, and painful – merely that they’re psychological in origin.

“This is a subconscious effect that occurs in patients who may be prone to anxiety or mood disorders,” Mechtler told TODAY’s Matt Lauer. “But these are definitely real symptoms.”

Mass psychogenic illness is a kind of conversion disorder, Robach reported. Conversion disorders occur when psychological stresses start to be expressed as physical symptoms.

The National Institute of Neurological Disorders and Stroke, NINDS, is currently conducting research on conversion disorders and is running a clinical trial to investigate uncontrollable shaking in people who have no known underlying brain or medical disorder.

The Le Roy students would be eligible to enroll in the trial, but officials can’t say whether any of them have signed up.

Regardless, not all the girls have accepted the diagnosis of mass psychogenic illness.

One of the original 12, Thera Sanchez, told TODAY, “I’m frustrated. No one’s giving us answers.” 

NBC's WHEC contributed to this report

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