MedicalResearch.com Interview with: Dimitry S. Davydow, MD, MPH Associate Professor Department of Psychiatry and Behavioral Sciences University of Washington School of Medicine Seattle, WA 98195 Dr, Davydow wishes to acknowledge Dr. Wayne Katon, the lead investigator of the study, who passed away on March 1, 2015. Medical Research: What is the background for this study? Dr. Davydow: The medical and public health communities have known for quite a while that diabetes and depression are both potential risk factors for developing dementia later in life. Dr. Wayne Katon previously published two articles detailing the results of two studies of relatively large groups of patients (one with nearly 4,000 patients and the other with 29,000 patients) with diabetes showing that those with diabetes and co-existing depression had a greater risk of developing dementia later in life than those patients with just diabetes. These initial studies were important since patients with diabetes are 3 to 4-times more likely to suffer from depression compared to the general population. However, it remained unclear when comparing to a population without either diabetes or depression, to what extent each independently raised the risk of developing dementia, and then to what extent having both conditions increased an individual’s subsequent risk of dementia. We sought to answer these questions with this study. In addition, with the growing obesity epidemic, which carries with it higher burdens of both diabetes and depression, there is reason to be concerned that the risk of dementia could be higher at even younger ages. To address this issue, we also wanted to see if there was a differential impact of the combination of diabetes and co-existing depression on dementia risk among those younger than 65 compared to individuals 65 or older. We were fortunate to be able to examine health data from all Danish citizens 50 or older over a 6 year period, a population numbering nearly 2.5 million people to be able to answer these questions. Medical Research: What are the main findings? Dr. Davydow: We found that compared to individuals without diabetes or depression, those with diabetes alone had about a 15% greater risk of developing dementia, those with depression alone had about an 83% greater risk of developing dementia, and those with both diabetes and co-existing depression had a 107% greater risk of developing dementia compared to those without either condition. We also found that of all of the cases of dementia diagnosed in Denmark among individuals 50 or older between 2007 through 2013, 6% were potentially due to combination of having both diabetes and depression. This was also true for those 65 or older, where 6% of all diagnosed dementia was potentially attributable to the combination of both diabetes and depression. However, among individuals under age 65, we found that 25% of all cases of dementia may have been directly attributable to the combination of diabetes and co-existing depression. (more…)