Groundbreaking methodology of analyzing teeth discovers environmental exposures and helps identify early markers of disease
Patients with amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, metabolize metals and essential nutrients differently from people without the disease, as evidenced in their teeth as early as the first ten years of life, according to a study published in March by Manish Arora, BDS, MPH, PhD, FICD, the Edith J. Baerwald Professor and Vice Chairman of the Department of Environmental Medicine and Public Health at the Icahn School of Medicine at Mount Sinai.
An often-fatal disease characterized by motor neuron death that leads to lost function in limbs and trouble breathing, ALS typically strikes people after age 50 and has no effective treatment.
“If we can find a signature five decades before a person has symptoms, that gives time to scientists and doctors to perhaps alter the trajectory,” says Dr. Arora. “They might never develop severe symptoms. At least we have a tool and some data to get us there.”
The breakthrough methodology of analyzing teeth to discover environmental exposures to help identify early markers of disease holds enormous promise, to potentially help prevent and better treat disease. Researchers of other diseases, including Irritable Bowel Disease (IBD), are already applying the method to advance their fields.
“If we can find a signature five decades before a person has symptoms, that gives time to scientists and doctors to perhaps alter the trajectory”
Dr. Manish Arora
“My hope is once we identify these biochemical pathways we can work with specialists in clinical management of the disease to start to repurpose existing drugs to modify those pathways,” says Dr. Arora, who first used tooth analysis to help discover the etiology of autism. In a widely cited study in 2018, he found that the shed baby teeth of children with autism contained different levels of the essential nutrients zinc, copper and toxic elements such as arsenic cadmium, compared with typically developing children. The abnormalities were apparent even before birth, in the third trimester of gestation. Baby teeth cannot be analyzed until age 5 or 6, when they are shed. But the findings could help alert pediatric doctors what to look for in blood and urine samples collected at birth, to identify vulnerable children and start treatment earlier.
Human teeth grow in a similar way to trees, with a new ‘ring’ developing every day, starting in early life. Certain environmental exposures are encoded in the rings.
“Fora long time, we suspected that ALS is driven by the environment from way back, maybe from the person was a child or baby,” says Dr. Arora, whose study was published in May 2020 in The Annals of clinical and translational neurology journal. “Less than ten percent of ALS is genetically driven. Ninety percent is non-genetic, or an interaction between the environment and genetics. But how do we figure out what we were exposed to as a baby? Was a parent a smoker? Which pesticide, how much? It sounds impossible. It’s expecting time travel. Yet we discovered we can use teeth for answers.”
Similar to patients with autism, ALS patients’ teeth exhibit systemic elemental dysregulation. The study, a collaboration with University of Michigan researchers, examined the adult teeth of 36 cases and 31 controls. Dr. Arora and his colleagues developed a decade-long trajectory of each subject’s exposures on a week-by-week resolution.
“Over ten years, I would have to collect 500 blood samples from each patient to get the same data that we got from a single sample, 50 years after the fact,” Dr. Arora says.
The study concluded that tooth analysis predicted an ALS diagnosis with 80 percent accuracy. Next, Dr. Arora plans to replicate the study in different geographic populations, increase the sample size and examine both adult and baby teeth.
“We wanted to make sure this work has broad reach and can help others studying early life programming for late-life diseases,” he says.