TUESDAY, May 29 (HealthDay News) -- Healthy brain nerve connections as you age may be a key to retaining intelligence later in life, according to a new study.

Researchers at the University of Edinburgh in Scotland found that older people with robust brain wiring (white matter, or nerve fibers that connect different, distant brain areas) processed information quickly, a sign of intelligence.

The study of 420 people who were born in 1936 and have been followed since they were 11 years old also found that those with brain wiring in poor condition had slower processing speeds, which also can impact thinking abilities.

The study suggests that deterioration of white matter with age is likely a significant cause of age-related mental decline, and that intelligence is not found in a single part of the brain, researchers said.

"Our results suggest a first plausible way how brain structure differences lead to higher intelligence," study author Lars Penke said in a university news release. "The results are exciting for our understanding of human intelligence differences at all ages."

In the study, researchers measured seniors' performance on timed tests and how much water is in brain tissue, which they say is a window into the condition of the white matter.

"This research is very exciting, as it could have a real impact on tackling mental decline in later life, including dementia," James Goodwin, head of research at the charity Age UK, said in the news release. "With new understanding of how the brain functions, we can work out why mental faculties decline with age in some people and not others, and look at what can be done to improve our minds' chances of aging better."

Age UK funded the study, which was published in the journal Molecular Psychiatry.

More information

The Society for Neuroscience has more about healthy brain aging.