A new study comparing risk factors for Alzheimer’s disease has found that having a high amount of beta amyloid plaques in the brain is associated with greater mental decline in healthy, older people than carrying a gene thought to increase people’s risk for the disease.

According to study author Yen Ying Lim, at the University of Melbourne in Victoria, Australia, prior research has shown that carrying the ‘Alzheimer’s gene,’ called the APOE ε4 allele, and plaques have both been associated with increased risk of cognitive decline and the eventual development of Alzheimer’s disease.  The gene also increases the risk of plaques.

Therefore, Lim and her colleagues originally thought that having both the gene and a high amount of plaques together would result in greater cognitive decline.  

However, “the data suggested that while both plaques and the gene were associated with decline in healthy people, the main driver of this decline was the amyloid plaque,” Lim told FoxNews.com.

In a study of 141 healthy people with an average age of 76, the researchers found people who had more plaques at the start of the study had up to 20 percent greater cognitive decline over the next year and a half than those who had fewer plaques.  

More On This...

While people who carried the Alzheimer’s gene also showed greater decline than people without the gene, the gene did not affect the decline in memory caused by the plaques.

Though the evidence indicates plaques may be a more important factor in determining Alzheimer’s risk or other brain-related diseases, there are challenges to scanning people for plaques rather than the APOE ε4 allele.  

“The main challenge is cost – scans are very expensive, and the number of scanners are very few,” Lim said. “Further, this is the first time such a relationship between amyloid and cognitive decline has been observed.”

If the results are replicated in future studies, Lim added, it could help direct future researchers on how to potentially treat or prevent Alzheimer’s disease.

“It provides us with a platform to begin to investigate whether in healthy people with high levels of plaques, pharmaceutical therapies designed to halt or alter plaque accumulation can prevent the disease from progressing to the more severe stages,” Lim said.

The study was published this week in the journal Neurology.