(PARIS) -- Call them senior moments, mental glitches or simple forgetfulness -- many people have experienced the mental slowdown that can come with age.
New research finds that these cognitive slips can begin as early as age 45. But whether they are the result of dementia, cardiovascular disease or simply getting older is not clear.
Researchers studied a group of nearly 7,500 British government employees between the ages of 45 and 70, periodically testing their memories, reasoning, vocabulary and comprehension skills for 10 years.
Overall, the 45- to 49-year-olds showed a decline of nearly 4 percent on average in their cognitive capabilities over 10 years.
That amount of decline is probably not enough to cause impairment in daily life, said study author Archana Singh-Manoux, research director of the Center for Research in Epidemiology and Population Health at Hopital Paul Brousse near Paris -- but it could be an important red flag for future problems.
"This might well be part of the normal aging process," Singh-Manoux said. "However, other studies have shown that small differences in cognition might translate to greater differences in risk of dementia at older ages."
The study participants' cognition slipped even further as they got older. By age 65, men's cognitive performance declined by almost 10 percent, and women's dropped by 7.5 percent.
According to Singh-Manoux, this study, published Friday in the British Medical Journal, is the first to document cognitive declines at such a young age.
"The understanding of cognitive aging so far was of no cognitive decline until age 60," she said. "Our study shows that this is not the case. Cognitive function begins to decline earlier."
But how much that mental drop-off indicates a slide into more debilitating dementia is unclear. The current study didn't measure how many of the participants went on to develop dementia.
Copyright 2012 ABC News Radio