Researchers from the University of California, San Francisco, studied more than 15,000 participants, at different stages of life. They found that those with depressive symptoms in their 20s were 75% more likely to have complete cognitive decline in old age.
“Overall, we found that the higher the symptoms of depression, the lower the cognition and the faster the rates of decline,” said first author of the study, Dr. Willa Brenowitz, of the University of California, San Francisco’s Department of Psychiatry and Behavioral Sciences, in a news release.
It is estimated that older adults have moderate or high depressive symptoms early in adulthood, and have been found to have cognitive decline over 10 years.
During the new study, published Wednesday, September 29, in the journal Alzheimer’s Disease, the team recruited nearly 15,000 volunteers aged between 20 and 89.
The participants were divided into three age groups, young (aged 20-49), middle-aged (aged 50-69) and older (aged 70-89), and all were screened for depression.
Next, the researchers developed a statistical model to predict the mean course of depressive symptoms. This pathway helps the team make an estimate of the mental health status of older adults with dementia when they were younger.
The model was then applied to 6,000 older study participants who had a history of cognitive decline.
The results revealed that young adults with depression were 73 percent more likely to experience cognitive decline later in their lives. This depression in early adulthood was also associated with decreased cognition 10 years after symptoms began.
There was also a later risk of dementia for those who developed depression in middle age or older, but the risk was not as high at 43%.
The researchers hypothesized that people with depression have a large number of stress hormones, which can destroy the ability to form new memories.
“Several mechanisms explain how depression can increase the risk of dementia,” Prinotiz said, among them that hyperactivity in the central stress response system increases production of glucocorticoid stress hormones, resulting in damage to the hippocampus, a part of the brain essential for forming, regulating and storing memories. new”.
The researchers say that with 20% of Americans suffering from depression, clinicians should be sure to look for cognitive decline in their patients.
“Future work will be needed to confirm these findings, but in the meantime, we must examine and treat depression for many causes,” said lead researcher Dr. Kristin Yaffe, from the Departments of Psychiatry, Behavioral Sciences, Epidemiology and Biostatistics at UCSF.