A new study finds that adults over 65 that are diagnosed with depression are twice as likely to be diagnosed with dementia later in life as their peers who are not depressed.  Although the mechanism behind this link has yet to be determined or understood, the findings support a growing theory that mood disorders and mild cognitive impairment speed up brain aging. 

Depression and Cognitive Impairment After 65 Linked to Faster Brain Aging“People, who suffer from depression and mild cognitive impairment after the age of 65, are more likely to have biological and brain imaging markers reflecting a greater vulnerability for accelerated brain aging, researchers at the University of Pittsburgh School of Medicine reveal.

According to senior investigator Meryl A Butters, older adults with severe depression have a two-fold increased risk of developing dementia later in life as compared to those who have no mood disorders. But not much is known on the underlying mechanism that links depression to an increased risk of dementia – a chronic progressive brain disease. Till date, studies have focused on just one or two biomarkers.

“Our study represents a significant advance because it provides a more comprehensive and integrated view of the neurobiological changes related to mild cognitive impairment in late-life,” she said. “Better understanding of the neurobiology of cognitive impairment in depression can provide new targets for developing more specific treatments, not only for its prevention and treatment, but also for its down-stream negative outcomes, including the development of dementia and related disorders.”

To proceed with the finding, researchers collected blood samples from 80 older adults in remission after they were treated for major depression. Out of the total subjects, 36 had MCI and 44 had normal cognitive function. They looked for 242 proteins in blood samples. The proteins were involved in biologic pathways linked with cancer, cardiovascular diseases, and metabolic disorders as psychiatric and neurodegenerative disorders.

Apart from this PET and MRI scans were done on the participants to identify indicators of cerebrovascular disease, brain atrophy or shrinkage and beta-amyloid – the protein that makes up brain plaques linked with Alzheimer’s.

They noticed that the MCI group showed more differences in 24 protein’s biological activity that is involved in controlling immune and inflammatory pathways, protein and lipid balance. MCI group had a greater tendency for cerebrovascular diseases, as revealed by brain scans.

“If you take these results altogether, they suggest that people with depression and cognitive impairment may be more vulnerable to accelerated brain aging, which in turn puts them at risk for developing dementia,” Dr. Butters said. “Ultimately, if we can understand what happens in the brain when people are depressed and suffer cognitive impairment, we can then develop strategies to slow or perhaps stop the impairment from progressing to dementia.”

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