What are zombie cells? What could cure Alzheimer’s disease?

Miranda Orr, an assistant professor at Wake Forest University School of Medicine, believes older, malfunctioning cells called senescent cells play a significant role in Alzheimer’s disease. That’s why she’s conducting human trials that involve eradicating these so-called “zombie cells” with senolytic drugs, according to National Geographic.

“In a placebo-controlled study of 48 patients, Orr is testing her theory that senolytics can protect a brain in the early stages of Alzheimer’s from getting ravaged,” the article said.

Alzheimer’s disease slowly destroys an individual’s memory to the point of debilitation, per the National Institute on Aging. Its name comes from Dr. Alois Alzheimer, who studied the brain tissue of a woman experiencing memory loss, difficulty communicating and “unpredictable behavior.”

Dr. Alzheimer found amyloid plaque and neurofibrillary in the woman’s brain after she died. These two issues, as well as a loss of connection between neurons, are currently considered the main features of Alzheimer’s disease, which is primarily caused by old age, according to the National Institute on Aging.

Most doctors looking for Alzheimer’s cures have focused on reducing brain plaque. But this method, though proven capable of slowing Alzheimer’s disease, cannot cure patients and has painful complications. The University of Rochester Medical Center reports that roughly 12.5% of participants in one study involving plaque-clearing drugs “showed evidence of mild to moderate localized brain swelling.”

Orr is trying to cure Alzheimer’s not through plaque clearance, but by targeting cells that have ceased to divide. These senescent or “zombie” cells are usually triggered by types of stress such as DNA damage, oxidative stress, or oncogene activation, according to the NIH. 

Although senescent cells prevent cancer development by limiting the rapid division rate of damaged cells, they contribute to aging and chronic diseases by secreting inflammatory and harmful molecules, affecting normal cells, per research from the University of California, San Francisco.

Senolytics are a class of drugs that destroy senescent cells while preserving healthy cells, according to National Geographic. Studies using senolytics on mice show a successful increase in age and health. 

In her 48-patient study, Orr is testing if senolytics can prevent further brain damage in early-stage Alzheimer’s patients.

Currently, Alzheimer’s disease affects 6.7 million Americans and kills more seniors than breast cancer and prostate cancer combined, according to the Alzheimer’s Association. There’s still much unknown about the disease, and in hopes of discovering a cure, Orr is trailblazing new ways of learning more about this illness.