A new study has shown that major depression more than doubles the risk of dementia among adults with diabetes.

Dementia is the progressive decline of thinking and reasoning abilities. These can include memory loss, difficulty with basic math, wandering, living in the past, personality changes, and not recognizing familiar people.

"Diabetes alone has shown to be a risk factor for dementia, as has major depression by itself," said the lead author of the study, Dr Wayne Katon, University of Washington (UW) professor of psychiatry and behavioral sciences.

The study team also included researchers from the Group Health Research Institute in Seattle and the Veterans Affairs (VA) Puget Sound Health Care System, as well as UW researchers in medicine and in epidemiology.