Depression may be early sign of Alzheimer's disease

A new study suggests that in some people, new-onset depression may stem from the buildup of toxic plaque in the brain that has long been associated with Alzheimer's disease.

"Our findings provide additional support for depressive symptoms as an early feature of preclinical Alzheimer's disease," wrote the team, led by Catherine Munro, MD, MD, of Brigham and Women's Hospital in Boston, USA. Neuropsychologist.

Dr. Marc Gordon, another expert who was not involved in the study, explained: “It’s not that depression causes Alzheimer’s, it’s that the pathology of Alzheimer’s affects this part of the brain. In part, this leads to depressive symptoms early in the course of the disease.”

He is chief of neurology at Northwell Zucker Hillside Hospital in Great Neck, New York.

As the Boston researchers note, "Neuropsychiatric symptoms, particularly depression, are common in Alzheimer's disease." But the exact link between depression and Alzheimer's disease is unclear.

In the new study, Munro and colleagues tracked the incidence of depressive symptoms in 154 people participating in the ongoing Harvard Brain Aging Study.

None of the participants in the study were mentally impaired, and the data was collected between 2010 and 2022. The data include results from PET scans of each patient's brain every two to three years, for an average of just under nine years.

These scans look for the buildup of amyloid plaques in brain tissue - a known hallmark of Alzheimer's disease.

Munro's team reports that among people who entered the study with mild or no symptoms of depression, "increased depressive symptoms were associated with early amyloid accumulation in brain regions involved in emotion control."

They note that this link between depression and amyloid buildup occurs regardless of whether memory or thinking problems have begun.

Gordon said the new data could help clear up some confusion about the link between depression and Alzheimer's disease.

"I think in the past this might have sometimes been misunderstood as what's called 'pseudo-depression' - where people with cognitive impairment seem to have depression-like symptoms," he explains. "But I think it's clear that depression can be an early manifestation of the disease."

In other words, people don't always become depressed because they have the mental difficulties associated with Alzheimer's disease—their depression may be related to the same underlying amyloid buildup associated with Alzheimer's disease.

"I think this paper shows that actual neuropathology of disease in certain parts of the brain may be responsible for the relatively early onset of depressive symptoms, independent of cognitive symptoms," Gordon said.

According to Munro's team, these insights could identify depression as a potential symptom of Alzheimer's disease in people at higher risk - symptoms that precede cognitive difficulties.

They note that early detection of Alzheimer's disease is increasingly important in an era when newly approved drugs can help slow the disease.

These amyloid-targeting drugs may even have the potential to curb cognitive decline and any mood/behavioral problems, such as depression, Gordon said.

However, he stressed that all of this research is in its early stages, so "we don't know yet," that's for sure.

Boston researchers agree that symptoms of depression may one day become part of the checklist for diagnosing Alzheimer's disease.

They said the findings "underscore the importance of monitoring for new and increasing affective [mood] symptoms in addition to cognitive changes in older adults presenting to psychiatric clinics and when screening for Alzheimer's disease."

(Compiled by: Wang Jimin)

(Editor: Jiang Qiming)

(Source of the article: Compiled and published by New Sancai)