Like my grandmother, about 5.4 million Americans suffer from Alzheimer’s disease–a terrible illness that inflicts memory loss and dementia on people as their brains accumulate microscopic plaques and tangles of protein. Despite decades of research, we still don’t know what causes most cases of Alzheimer’s. However, American and Emirati researchers are using mice to investigate a potential cause: exposure during infancy to lead, a toxic element banned from gasoline since 1995. By better understanding how lead causes the microscopic tangles of protein in mouse brains, the researchers hope to identify future drug targets for treating Alzheimer’s disease.
To investigate the link between lead and Alzheimer’s, the researchers exposed mice to lead at different life stages. Some mice consumed lead during infancy, while others drank lead-contaminated water as adults. Still others were exposed as both infants and adults. Two years later, when the mice were elderly, the researchers compared the brains of the lead-exposed mice to others never exposed to lead. They found that the mice exposed in infancy had more of the tangled protein, tau, compared with the unexposed mice and those only exposed as adults. But there wasn’t simply more tau: a greater proportion of tau was attached to phosphate, an important chemical used by the body.
People with Alzheimer’s also have too much phosphate-covered tau–and the more phosphate-covered tau a person has, the worse their dementia. The researchers suggest that investigating how the body controls the amount of tau in the brain, and how much phosphate attaches to it, will be important for understanding Alzheimer’s and identifying new areas for drug development.
Although my grandmother died several years ago from Alzheimer’s, new research like this makes me hopeful for myself and others at risk of Alzheimer’s–and very, very glad that lead has been banned from gasoline in the United States.