Over the five-year period, 36 of 455, or 7.9 percent, of the diabetes patients with major depression were diagnosed with dementia. Among the 3,382 patients with diabetes alone, 163 or 4.8 percent 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.
The team's previous findings from earlier studies showed that depression increases the mortality rate among people with diabetes, as well as the rate of complications such as heart, blood vessel, kidney and vision problems.
The exact manner in which diabetes and depression interact to result in poorer outcomes is not certain. Some studies suggest that a genetic marker for dementia is associated with a faster cognitive decline. Depression may also raise the risk of dementia, the authors noted, because of biological abnormalities linked to this affective illness, including high levels of the stress hormone cortisol, poor regulation in the hypothalamus-pituitary system, or autonomic nervous system problems that can affect heart rate, blood clotting, and inflammatory responses.
Depression, they added, might also raise the risk of dementia because of behaviors common in the condition, such as smoking, over-eating, lack of exercise, and difficulty in adhering to medication and treatment regimens. In the current study, patients with both diabetes and major depression were more likely to be female, single, smokers, physically inactive, and treated with in
|Contact: Leila Gray|
University of Washington