Depression and type 2 diabetes can increase a person’s chances of developing dementia, according to a new study.

While the risks were high for those who had either depression or type 2 diabetes, it went up even more for people who had both conditions.

Researchers concluded that people who only had diabetes had a 20 percent greater risk of developing dementia. Those who only had depression had an 83 percent greater risk for later having dementia.

The risk was highest in those who had both depression and diabetes. In that population, people had a 117 percent greater risk of developing dementia.

The study was published in JAMA Psychiatry.

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Dr. Dimitry Davydow at the University of Washington School of Medicine in Seattle and his colleagues conducted the study. They looked at data from 2007 to 2013 for more than 2.4 million Danish citizens who were over the age of 50.

Of the participants, 19 percent had been diagnosed with depression and 9 percent had diabetes. Overall, about 4 percent had diabetes and depression. The rest had neither condition.

The average age for diagnosis of type 2 diabetes was 63 years while the average age for depression diagnosis was 58 years. 

Davydow said they chose Denmark because it has healthcare records for all citizens. This allowed the team to analyze health data from a large population.

According to the research, 2.4 percent of the participants were diagnosed with dementia. The average age of diagnosis was about 81 years. Of those with dementia, 26 percent had depression, almost 11 percent had diabetes, and slightly less than 7 percent had both conditions.

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Doomed to Dementia?

“Individuals with diabetes and/or depression are most certainly not powerless to avoid dementia in later life,” Davydow said. 

He said the healthcare system needs to do better at early diagnosis of diabetes and depression and offer patients evidence-based treatments for these conditions. The system also needs to better educate patients on self-care.

“I think it is important to point out that arguably the best treatment available for dementia is to prevent it from developing since we don't have any treatments currently that either greatly improve quality of life for patients with dementia or reverse the course of the disease,” he said.

Aging and genetic risk factors that lead to dementia cannot be prevented, but “diabetes and depression are things that we can do something about.”

Davydow said the researchers want to look into additional questions raised by the study’s results. First, they want to understand why diabetes and depression increase the risk of dementia, particularly the combination of having both conditions. 

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