Ph.D. student explores new link between insecticide and Alzheimer’s disease

Ferass Sammoura first crossed paths with insecticides while playing soccer with his friends in the city streets of Lebanon.

“I remember seeing big trucks with tanks spray a fog of insecticides throughout the streets,” Sammoura says. “When they finished, they told us it was OK to continue playing. So, we would wait for the fog to disappear and go back out to play.”

For Sammoura, it was an introduction to what would later become his focus of study in the United States.

“Knowing what I know now, I would’ve told myself to stay inside or far away from the fog. Unfortunately, for a lot of kids, these things are unavoidable and an afterthought,” Sammoura says. “The reality is that pesticides have a practical use and are needed to control pests, but the understanding behind their potential harms toward us in the long-term is not well understood.”

Today, Sammoura is a Ph.D. student focusing on brain, behavior and the environment at FIU's Robert Stempel College of Public Health & Social Work. When he’s not running community and student engagement activities as the vice president of the Environmental Health Student Association, he’s in Professor and Stempel's Associate Dean for Research Jason Richardson’s lab conducting research around the environmental impacts of insecticides— research that will soon get some exposure.

Last month, Sammoura won a travel award to present his abstract titled DDT and its metabolite DDE increase levels of Amyloid Precursor Protein and secretion of Amyloid Beta at the Society of Toxicology’s Annual Meeting and ToxExpo in March 2022.

DDT is a synthetic insecticide that was extensively used through the 40s and 60s to combat insect-borne diseases like malaria and treat crop and livestock production. In 1972, the Environmental Protection Agency banned its general use in the United States due to its harmful environmental effects. Since then, the public health community has taken a closer look at DDT’s impacts on people and the environment. In 2014, Richardson published a study in Jama Neurology while he was at Rutgers University that presented evidence linking exposure to DDT with Alzheimer’s disease.

As a graduate assistant in Richardson’s lab, Sammoura has access to resources that help him further explore the links between the insecticide and the disease. “It’s a dynamic, critical-thinking type of lab. Richardson is very collaborative and likes to get input from everyone,” Sammoura says.

Under Richardson’s mentorship, Sammoura’s research explores how DDE — the substance produced when DDT metabolizes — impacts the amyloid pathway, a hallmark of Alzheimer’s disease.

“DDE has long been thought to be inactive and not to harm people,” Sammoura says. “What we’re finding is that at the very same, very low concentrations it can induce the same effects that DDT is doing.”

Using mouse and cell models, Sammoura has found that DDE increases the levels of the Amyloid Precursor Protein, a protein found in healthy brains. When broken down, the protein can form amyloid-beta peptides which at abnormal amounts can turn into plaques that are associated with Alzheimer’s disease. These plaques in the brain are a global hallmark of the condition. “It’s just one piece of a very complicated puzzle,” he says.

Sammoura hopes that his research will help scientists better understand the effects of DDT and DDE exposure, and how they impact different populations and genotypes. “It’s complex but the basics of what I’m doing is propelling us to that step.”