Depression can more than double the risk of developing dementia among diabetics, says a new study.
“Diabetes alone has shown to be a risk factor for dementia, as has major depression by itself,” Dr Wayne Katon of University of Washington, who led the study, published in the ‘Journal of General Internal Medicine’ said.
According to researchers, various other population studies have shown that the risk of Alzheimer’s, vascular dementia, and other types of dementia is from 40 per cent to 100 per cent higher in people with diabetes, compared to people without diabetes.
“We wanted to determine the effects of both conditions — diabetes and major depression — occurring together. Our analysis suggests that major depression more than doubles the risk of dementia in adults with diabetes,” Katon said.
For the study, the researchers tracked the outcomes of adults from the Group Health Cooperative’s diabetes registry who agreed to participate. They were patients from nine Puget Sound area primary-care clinics in western Washington state.
The clinics were chosen for their socioeconomic and racial and ethnic diversity and were demographically similar to the area’s population. Initial enrollment of patients took place between 2000 and 2002, and the patients were studied for five years. Patients already diagnosed with dementia were excluded from the study.
Over the five-year period, 36 of 455, or 7.9 per cent, of the diabetes patients with major depression were diagnosed with dementia. Among the 3,382 patients with diabetes alone, 163 or 4.8 per cent developed dementia.
The researchers calculated that major depression with diabetes was associated with a 2.7-fold increase of dementia, compared to diabetes alone.
Because the onset of dementia can sometimes be marked by depression, the researchers also adjusted their hazard model to exclude patients who developed dementia in the first two years after their depression diagnosis.
In the study, patients with both diabetes and major depression were more likely to be female, single, smokers, physically inactive, and treated with insulin. They also had more diabetes complications and a higher body mass index, a ratio calculated from height and weight.
However, these differences were controlled for in the analysis and depression remained an important risk factor.
“It seems prudent for clinicians to add effective screening and treatment for depression to other preventive measures such as exercise, weight control, and blood sugar control to protect against the development of cognitive deficits in patients with diabetes,” the researchers said.