PHILADELPHIA — The National Institutes of Health have awarded an epidemiology professor at the University of Pennsylvania $11 million to study the link between chemical exposures and dementia.
The project will test blood and urine samples from thousands of people, looking for traces of environmental chemicals such as pesticides and metals, and seeing which are found more frequently in people who eventually develop Alzheimer’s and similar disorders.
The goal is “to understand more about environmental potential contributors to cognitive decline and Alzheimer’s,” said lead author Aimin Chen, a senior environmental epidemiologist at Penn.
The researchers will study samples collected from people who have been followed since the 1980s as part of a long-term study about the risks of coronary artery disease. The participants joined the study when they were an average of 25 years old, so they are soon to be in their 60s, when the signs of cognitive decline can start to appear.
Having exposure data over decades is crucial, said Chen, because the physical hallmarks of Alzheimer’s can appear in the brain a decade or more before people are diagnosed with memory loss. By testing study participants’ blood and urine for exposures to chemicals in early adulthood and middle age, “we can probably get a better understanding of the original trigger and causes” of dementia, he noted.
Another benefit of the patient group is that it includes roughly equal numbers of white and Black people. This is important, said Chen, because Black people are more likely to develop Alzheimer’s, but are often underrepresented in studies of the disease.
What researchers are looking for
Along with pesticides and metals, the researchers will comb the samples for traces of polychlorinated biphenyls, which are chemicals that used to be found in glues and plastics, among other sources. They will also test for polybrominated diphenyl ethers, which have been used in flame retardant materials found in furniture and rugs.
The participants have also shared information about their education and socio-economic backgrounds, which Chen and his team can use to determine how these so-called social determinants of health impact future risk of dementia.
The researchers will even consider the potential role of unidentified chemicals in dementia risk.
Using an analysis tool known as mass spectrometry, they can identify unknown chemicals in participant samples. If one type of unknown chemical or compound appears more frequently in the samples from people who eventually develop cognitive decline, the researchers can then study the unknown substance in more detail — determining if it comes from the environment, a prescription drug, or the diet, for instance.