Earliest Stage Of Alzheimer’s Disease May Be Brain Plaques, Which Can Appear 10 Years Before Symptoms

Plaque in the brain Interferes with Neuronal Functions

New research from the Keck School of Medicine at USC may have identified the earliest sign yet of Alzheimer’s disease. According to the new study, adults can develop elevated levels of amyloid plaque in the brain up to 10 years before they experience any of the cognitive decline associated with Alzheimer’s. Discovering these plaques so early could help certain patients take better preventive measures.

The appearance of plaques suggests that the brain destruction associated with Alzheimer’s disease can begin years before any symptoms are detected, but it also means that treatment can begin earlier, too.

“This study is trying to support the concept that the disease starts before symptoms, which lays the groundwork for conducting early interventions,” said Michael Donohue, lead author of the study, in a statement.“We’ve learned that intervening before the heart attack is a much more powerful approach to treating the problem.”  The same holds true for Alzheimer's, he says. 

For the study, the team measured the amount of amyloid plaque in the brains of 445 cognitively normal people for up to 10 years. Results showed that after 4 years, 32 percent of the individuals with elevated amyloid had developed symptoms of early-stage Alzheimers, compared to only 15 percent of participants with normal levels of amyloid. 10 years later,  88 percent of people with elevated amyloid showed a significant decline on cognitive tests, compared to only 29 percent of people with normal amyloid, IFL Science.

The team hope that removing this amyloid buildup at the very earliest signs could help to slow down or even prevent Alzheimer’s disease.

“We need more studies looking at people before they have Alzheimer’s symptoms,” said senior author Paul Aisen in a statement. “The reason many promising drug treatments have failed to date is because they intervened at the end-stage of the disease when it’s too late. The time to intervene is when the brain is still functioning well — when people are asymptomatic.”

While the study suggests that early plaque buildup in the brain could be the earliest sign of the onset of Alzheimer’s disease, it may not be a definitive harbinger of the disease. According to Aisen, one in three people over the age of 65 have elevated amyloid in the brain.

Today, over 5 million Americans have Alzheimer's disease and this number could rise to 16 million by 2050. The disease is the 6th leading cause of death in the U.S., killing more than breast cancer and prostate cancer combined. Figuring out a way to stop the disease at its very earliest signs could be life changing for countless individuals.

Source: Donohue MC, Sperling RA, Peterson R, et al. Association Between Elevated Brain Amyloid and Subsequent Cognitive Decline Among Cognitively Normal Persons. JAMA . 2017