Researchers found that increasing symptoms of anxiety were linked to higher levels of beta-amyloid, which is a protein associated with Alzheimer's disease, in the brains of older people with normal cognitive functioning.
First study author Dr. Nancy Donovan, who is a geriatric psychiatrist at Brigham and Women's Hospital in Boston, MA, and team say that the results suggest that a rise in the sypmtoms of anxiety could be an early sign of Alzheimer's.
The findings were recently published in The American Journal of Psychiatry.
Alzheimer's disease is a form of dementia characterized by problems with memory and thinking, as well as changes in behavior.
It is estimated that around 5.5 million people in the U.S. are living with Alzheimer's, of whom around 5.4 million are over the age of 65.
The precise causes of Alzheimer's disease remain unclear, but scientists believe that beta-amyloid plays a key role. This is a protein that can form "plaques," which have been found to block nerve cell communication in the brains of people with Alzheimer's.
These plaques are considered to be a hallmark of the disease, and research has suggested that an increase in beta-amyloid levels can occur up to 10 years before the onset of Alzheimer's symptoms.
According to the new study, anxiety could play a significant role in increased beta-amyloid levels among older adults.
Targeting anxiety may slow Alzheimer's
For their study, Dr. Donovan and colleagues sought to determine whether or not beta-amyloid might play a role in this association.
The research included 270 adults between age 62 and 90, with normal cognitive functioning, all of whom underwent positron emission tomography at study baseline and annually during 5 years of follow-up, in order to determine levels of beta-amyloid in their brains.
Symptoms of anxiety and depression among the adults were assessed using the 30-item Geriatric Depression Scale.
It was found that adults who showed an increase in anxiety symptoms over 5 years of follow-up also had higher levels of beta-amyloid in their brains. The researchers say that this indicates that worsening anxiety might be an early sign of Alzheimer's disease.
"If further research substantiates anxiety as an early indicator, it would be important for not only identifying people early on with the disease, but also, treating it and potentially slowing or preventing the disease process early on."
Dr. Nancy Donovan
The scientists point out that follow-up studies are required to determine whether older adults who experience an increase in anxiety symptoms actually go on to develop Alzheimer's.