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Past studies have suggested depression and other neuropsychiatric symptoms may be predictors of Alzheimer’s progression during its “preclinical” phase—a period marked by the accumulation of brain deposits of fibrillar amyloid and pathological tau in a patient’s brain.
In the current study, Nancy J. Donovan, M.D., of Brigham and Women’s Hospital and colleagues examined the association between brain amyloid beta and depression symptoms over time in cognitively normal, older adults.
A total of 270 participants aged 62 to 90 underwent baseline positron emission tomography (PET) scans to measure cortical aggregate amyloid beta and annual depression assessments with the 30-item Geriatric Depression Scale (GDS). The team calculated total GDS scores as well as scores for three GDS item clusters: apathy-anhedonia, dysphoria, and anxiety-concentration. These scores were examined over a span of five years.
“Rather than just looking at depression as a total score, we looked at specific symptoms such as anxiety,” Donovan said in a press release. “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.”
“These results suggest a direct or indirect association of elevated amyloid beta levels with worsening anxious-depressive symptoms and provide support for the hypothesis that emerging neuropsychiatric symptoms represent an early manifestation of preclinical Alzheimer’s disease,” the researchers wrote. “Further longitudinal follow-up is necessary to determine whether these escalating depressive symptoms give rise to clinical depression and/or MCI and dementia stages of Alzheimer’s disease over an extended period.”
For related information, see the Psychiatric News article “Alzheimer’s-Associated Protein Might Help Brain Fight Infections.”
(Image: iStock/fzant)