Warning signs of ALS can be found in teeth long before symptoms appear, study finds
New research shows that teeth can reveal what toxic metals a person was exposed to since birth — an important biomarker that links early metal exposure to the development of ALS long before symptoms appear.
It is the first study to use teeth to show that from birth, patients with amyotrophic lateral sclerosis process metals in higher concentrations and do so differently than healthy individuals, bringing scientists closer to understanding what causes the debilitating disease.
The paper was published Thursday in the journal Annals of Clinical and Translational Neurology.
“How do I go back in time to figure out what I was exposed to at birth or the first 10 years of life? Now we have a way to read those archives,” Dr. Manish Arora, senior author of the study and vice chair of environmental medicine and public health at the Icahn School of Medicine at Mount Sinai in New York, told McClatchy News.
“It’s like taking a blood test every week on these participants … and we were able to do it with a single sample,” he said.
ALS, also called Lou Gehrig’s disease, usually appears in patients around 40 to 70 years old. It affects nerve cells in the brain and spinal cord, according to The ALS Association.
In Greek, ALS stands for “no muscle nourishment,” because the disease largely affects voluntary movement like speaking, walking, eating and even breathing, the group said.
The researchers collected 36 teeth from ALS patients during autopsy, and another 31 from healthy individuals during routine dental extractions at the University of Michigan School of Dentistry, according to the study.
Each tooth was scanned with a laser beam at over 5,000 locations that mapped out the growth rings — similar to those in trees — that form daily since birth. The metal deposits in each tooth were then counted using a mass spectrometer.
“Essential nutrient elements and toxic metals that enter the blood circulation after exposure or as part of normal metabolism are captured in these chronological rings,” and are stable enough to study even when a person has died, the study said.
The team detected 11 metals in the teeth growth rings from birth to about 10 years of age, including chromium, manganese, nickel, tin and zinc, “all of which have been associated with ALS after diagnosis,” the study said.
Some of the results showed that zinc, for example, was metabolized 2.46 times more than healthy individuals and nickel was processed 1.65 times more in ALS patients.
A follow-up model showed that mice with an ALS gene also metabolized metals differently after researchers looked at their brains, Dr. Arora told McClatchy News.
Only about 10% of ALS patients inherit a mutated gene that likely leads to their diagnosis, but the remaining 90% occur without this family history, according to The ALS Association.
In addition to metals, other environmental factors have been suspected to cause ALS, such as pesticides, some viruses, radiation and even warfare, the group said, adding that military veterans are about twice as likely to develop the disease than the average person.
It’s known that deficiencies and excess of toxic metals in the body can lead to ALS symptoms, but when this exposure and special processing begins has been a mystery until now.
At any given time, at least 16,000 Americans have the disease, The ALS Association said. And “every 90 minutes, someone is diagnosed with the disease and someone passes away from it.”
Arora hopes the study inspires therapeutic treatments for the disease and suggests testing should continue to protect future generations of children from toxic metal exposure.
Future research should include larger sample sizes from several different locations and consider how racial and ethnic differences affect metal processing in the body, Arora said. The role of a lifetime of smoking should also be studied.
“We hope in the long term, after validation of this work in larger studies, that this will lead to preventive strategies,” Arora said in a press release. “What’s exciting about this work is that we are looking at biological pathways that we could potentially modify with drug development.”
This story was originally published May 21, 2020 at 12:29 PM with the headline "Warning signs of ALS can be found in teeth long before symptoms appear, study finds."
