Depression Doubles Risk of Dementia But doctors aren't sure why By Kevin Spak, Newser Staff Posted Jul 6, 2010 2:49 PM CDT 5 comments Comments Depressed people are much more likely to develop dementia. (Shutterstock) (Newser) – Depression sufferers are nearly twice as likely to develop dementia later in life, according to a pair of new studies. Doctors aren’t entirely sure why that is, and stress that they can’t prove that one causes the other. But they theorize that the brain inflammation that accompanies depression might have something to do with it, the BBC reports. Depression also increases the levels of certain potentially risky proteins. One study followed 949 elderly people for 17 years, and showed that dementia often followed depressive episodes; the other followed 1,239 people, and concluded that the more often a person was depressed, the more likely they were to develop dementia. The studies, one Alzheimer researcher says, indicate that “there may be profound connections” between the conditions.