Use it or lose it: Doing brain-stimulating activities from childhood -- like reading books, writing letters and solving everyday problems -- through old age may help prevent clinical signs of dementia such as memory loss, a new study finds.
"Certain things increase or decrease your vulnerability to cognitive [mental] decline," said Robert Wilson, the study's lead author.
Keeping your brain active seems to help certain brain circuits operate effectively, even if a gradual buildup of brain disease is already occurring, said Wilson, a professor of neurological and behavioral sciences at Rush University Medical Center, in Chicago.
People who engaged in frequent mental activity in later life had a rate of mental decline that was 32 percent lower than those with average activity. Meanwhile, those with infrequent mental activity experienced a decline in mental abilities that was 48 percent faster.
The research, published online July 3 in the journal Neurology, helps explain why one-third of people die in old age with little or no signs of problems with thinking, learning or memory, yet when brain autopsies are done, they actually have clear evidence of Alzheimer's disease, Wilson said.
"They [technically] have the disease, but it's not expressed clinically," he said.
That idea that the brain somehow creates a "work-around" to avoid showing signs of Alzheimer's or other dementia is often referred to as the "cognitive reserve hypothesis," Wilson said. That concept suggests that people with greater thinking, learning and memory abilities are somehow able to delay symptoms of Alzheimer's. But proving the hypothesis has been challenging for scientists.
"There's been this long-term debate in the field about how cognitive activities preserve cognition," said Prashanthi Vemuri, an assistant professor of radiology at the Mayo Clinic in Rochester, Minn., who wrote an editorial accompanying the study. The question has essentially been: Which comes first, the chicken or the egg?
"Does engagement in cognitive activities slow cognitive decline, or are people less interested in doing cognitive activities because they have problems with dementia?" Vemuri said.
She thinks the study breaks new ground. "It confirms that whatever is happening in the brain is happening, but the cognitively stimulating activities a person does independently slow down the progression of the disease."
How do intellectually challenging activities help support brain function?
The brain tries to constantly adapt to the challenges it's asked to do, Wilson explained.
"The brain is experience dependent," he said. "Activities that are sustained are going to impact its structure and function. And cognitive circuits that are elaborately structured and functioning very well are able to adapt when the inevitable onslaught of aging occurs."
The researchers conducted long-term follow-up and actually performed autopsies of the participants' brains after death to confirm the absence or presence of disease, Vemuri said.
The scientists began back in 1997, asking 294 participants -- all older than 55 -- to report on their lifetime and recent thinking-related activities, from childhood to young adulthood, middle age and the present. They tested participants' memory and thinking ability regularly, and did annual neurological exams. The participants were about 68 percent women, had 14 years of education and 37 percent had mild thinking impairment when they started in the study.
After each participant died, examiners who had no knowledge of the clinical evaluation data did an independent inspection of the brain, looking for established signs of dementia, called plaques, tangles, infarcts and Lewy bodies.
The researchers then compared those brain findings to the data they had collected, and found that current mental activity slowed the rate of mental decline years before death.
Wilson pointed out that the research doesn't prove cause and effect. A clinical trial would be needed for that -- which involves randomly assigning people to one set of behaviors or another -- and that would be unethical and inordinately expensive, he said. But he's now doing neuroimaging studies to better understand what it is about a cognitively stimulating lifestyle that helps protect the brain.
As for how to best protect your brain, Wilson recommended finding real-world activities -- rather than just crossword puzzles or Sudoku games -- that include a combination of challenges and the need to focus and concentrate. "Find a hobby that is sustainable: quilting, photography, acting in the theater, even learning Morse code," he suggested. "Physical activity is also important."
Vemuri encouraged people to start developing their thinking and memory skills as young as possible. "Parents should know that reading programs at a young age will help their kids have a good old age," she said.