HARTFORD, Conn. — Researchers at the UConn Center on Aging have uncovered causal links between depression and Alzheimer’s disease and related dementia (ADRD), sparking hope for potential interventions to prevent the disease.

The Alzheimer’s Association found that more than 7 million people in the country live with ADRD.

Dr. Breno Diniz, associate professor of psychiatry at UConn Health and the Center of Aging found that the link between depression and ADRD is observed in the increase of inflammation of the brain and the lower efficiency to remove a toxic protein called amyloid-beta from the brain.

“We can try to develop more specific interventions to prevent Alzheimer’s disease in this population instead of going broadly without a focus,” Diniz said.

Diniz explained that since the 1980s researchers have established that any history of depression throughout the lifespan, even in your 20s, is one of the most important risk factors for future development of Alzheimer’s disease.

UConn Today reported that between 11.1% and 14.7% of ADRD cases affecting roughly one million people in the United States are attributable to major depressive disorder.

But Diniz’s study, which was published in Nature Mental Health with co-authors from UConn including Dr. George Kuchel and Dr. Chia-Ling Kuo, and Richard Fortinsky, strengthened the association between Alzheimer’s disease and depression because researchers were able to identify the causal link between ADRD and major depressive disorder.

“This is the first time we have a more direct proof and observation of this link,” said Diniz.

Diniz began doing research on the link between depression and ADRD 15 years ago.

Kuchel, the director of the UConn Older Americans Independence “Pepper Center,” said the goal of the center is to enhance independence in older adults by better understanding differences in how individuals age.

“This study offers important new insights into why some individuals with depression are more likely to progress to Alzheimer’s disease and therefore may help identify individuals more likely to benefit from antidepressants or therapies targeting biological processes that drive both conditions.”

Kuchel said that while aging represents a key risk factor for many chronic conditions including Alzheimer’s disease, most older adults do not develop the disease.

Diniz said it is critical people understand that depression is a silent killer and that it must be treated adequately.

“We know people with depression have a higher risk of dying from all causes,” he said. “Depression makes you more prone to develop chronic medical conditions.”

He said studies have shown that treating depression with antidepressants does not always reduce the risk of dementia, but still is the best hope.

That is why he said this study is integral in understanding the link between ADRD and depression so more interventions can be developed to target inflammation in the brain and the removal of amyloids.

Diniz analyzed ADRD outcomes among middle-aged adults with depression from the United Kingdom Biobank, which is a large population of studies from the United Kingdom.

Researchers used mendelian randomization, which according to the National Institutes of Health, is “a method of studying the causal effects of modifiable exposures on health, social and economic outcomes using genetic variants associated with the specific exposures of interest,” to analyze the data.

In analyzing the data, Diniz and his co-authors merged proteomics, the study of proteins created by cells in the body, and genomics, the study of someone’s entire set of DNA, according to UConn Today and Diniz.

Researchers then developed a Proteomic Risk Score, which can calculate the risk of dementia in an individual, Diniz said.

“We established why depression can increase the risk of dementia in an individual,” he said. “Depression is a disease beyond a low mood. It has long-term consequences.”

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