A new study suggests a link between elevated amyloid beta levels and the worsening of anxiety symptoms.
According to researchers at Brigham and Women’s Hospital, the findings support the hypothesis that neuropsychiatric symptoms could represent the early manifestation of Alzheimer’s disease in older adults.
Past studies have suggested depression and other neuropsychiatric symptoms may be predictors of Alzheimer’s progression during its “preclinical” phase. In this phase, brain deposits of fibrillar amyloid and pathological tau accumulate in a patient’s brain. This phase can occur more than a decade before a patient’s onset of mild cognitive impairment.
For the new study, researchers examined the association of brain amyloid beta and longitudinal measures of depression and depressive symptoms in cognitively normal, older adults.
Their findings, published in The American Journal of Psychiatry, suggest that higher levels of amyloid beta may be associated with increasing symptoms of anxiety. The results support the theory that neuropsychiatric symptoms could be an early indicator of Alzheimer’s, according to the researchers.
“Rather than just looking at depression as a total score, we looked at specific symptoms, such as anxiety. When compared to other symptoms of depression, such as sadness or loss of interest, anxiety symptoms increased over time in those with higher amyloid beta levels in the brain,” said first author Nancy Donovan, M.D., a geriatric psychiatrist at Brigham and Women’s Hospital.
“This suggests that anxiety symptoms could be a manifestation of Alzheimer’s disease prior to the onset of cognitive impairment.”
“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,” she continued.
As anxiety is common in older people, rising anxiety symptoms may prove to be most useful as a risk marker in older adults with other genetic, biological, or clinical indicators of high AD risk, researchers point out.
For the study, researchers derived data from the Harvard Aging Brain Study, an observational study of older adults aimed at defining neurobiological and clinical changes in early Alzheimer’s disease.
The participants included 270 cognitively normal men and women, between 62 and 90 years old, with no active psychiatric disorders.
They underwent baseline imaging scans commonly used in studies of Alzheimer’s disease, and annual assessments with the 30-item Geriatric Depression Scale (GDS), an assessment used to detect depression in older adults, the researchers reported.
The researchers calculated total GDS scores, as well as scores for three clusters symptoms of depression: Apathy-anhedonia, dysphoria, and anxiety. These scores were looked at over a span of five years, according to the scientists.
The research team found that higher brain amyloid beta burden was associated with increasing anxiety symptoms over time in cognitively normal older adults.
The results suggest that worsening anxious-depressive symptoms may be an early predictor of elevated amyloid beta levels and, in turn, Alzheimer’s. The study’s findings also provide support for the hypothesis that emerging neuropsychiatric symptoms represent an early manifestation of preclinical Alzheimer’s disease, the researchers said.
Donovan notes further follow-up is needed to determine whether these escalating depressive symptoms give rise to clinical depression and the dementia stages of Alzheimer’s over time.
Source: Brigham and Women’s Hospital