Here’s what a new Harvard University study shows, based on brain scans of a group of volunteers.
Depression, which first appears after the age of 65, may be caused by the accumulation of the same pathological proteins that cause Alzheimer’s disease, US scientists say.
This finding suggests that mental illness may be an early manifestation of dementia and not always a consequence of it.
Relevant research Published in the medical journal JAMA Network Open. Neuropsychiatric symptoms, especially depression, are common in Alzheimer’s patients, the researchers wrote. However, the exact relationship between the two has not been fully elucidated.
To investigate the issue, scientists included 154 volunteers in their study. 61% were women. They were 65 or older at the start of the study. The data was collected between 2010 and 2022.
The researchers followed each of their volunteers for about 9 years. They assessed depressive symptoms and cognitive abilities annually. In addition, they had a positron emission tomography (PET scan) every 2-3 years to check for beta-amyloid deposits in their brains.
Beta-amyloid is a protein that accumulates in the brains of Alzheimer’s patients and forms toxic plaques.
Findings
Many of the volunteers had mild or no depression at the start of the study. Their increase in symptoms during the study “was associated with early accumulation of β-amyloid in brain regions associated with emotion regulation,” they note in their paper.
But crucially, the protein’s association with depression was independent of whether the volunteers already started to exhibit memory or thinking problems.
«Our findings support the idea that depressive symptoms in old age may be an early indicator of preclinical Alzheimer’s disease.“, scientists from Harvard University and other US academic centers write.
What do they mean?
In the past, many scientists believed that Alzheimer’s patients exhibited symptoms that mimicked depression. Now it turns out that “Depression can be a very early manifestation of Alzheimer’s disease“, he said Dr. Marc Gordon, Professor of Neurology and Psychiatry at Hofstra University, New York.
In other words, patients are not always depressed because of cognitive difficulties caused by Alzheimer’s disease. Their symptoms of depression may be related to pathology leads to disease.
«A new study shows that the neuropathology of the disease in certain parts of the brain causes these symptoms to start relatively early.explained Dr. Gordon, who was not involved in the study.
The researchers, in turn, speculate that depression may be an early indicator of dementia in high-risk individuals. This can lead to early diagnosis and initiation of treatment.
This is important because existing medications can slow its progression if given early in the course. In addition, they can and do slow the worsening of depression, Dr. Gordon. However, this has not yet been confirmed as the entire investigation is still at an early stage,” he added.
In any case, depressive symptoms that first appear after the age of 65 should not be ignored, they should be monitored. The researchers concluded that this is even more important in the context of screening for the development of dementia and Alzheimer’s disease.