Mental Decline Can Start at 45 British study surprises researchers By John Johnson, Newser Staff Posted Jan 6, 2012 1:23 PM CST 18 comments Comments Brain function can start declining in your 40s. (Shutterstock) (Newser) – A comprehensive new study has depressing news for people in their 40s: Memory loss and a general decline in brain function can start much earlier than thought, say about age 45, report Reuters and USA Today. The study of 7,000 office workers in Britain refutes the generally held notion that such decline doesn't begin until age 60 or so. "We were expecting to see no decline, based on past research," says one of the researchers, but no such luck. The findings could have a profound effect on dementia research, along with when drugs used to treat it are administered. The good news is that about a third of participants showed no decline at all between the ages 45 and 70, so everyone can tell themselves they're in that camp.