Scientists are the first compelling evidence in people that cognitive training can boost levels of a brain chemical that typically declines with age.
A 10-week study of people 65 or older found that doing rigorous mental exercises for 30 minutes a day increased levels of the chemical messenger by 2.3% in a brain area involved in attention and memory.
The increase "is not huge," says , a neurologist at McGill University in Montreal. "But it's significant, considering that you get a 2.5% decrease per decade normally just with aging."
So, at least in this brain area, cognitive training appeared to turn back the clock by about 10 years.
The chemical change observed after intensive brain training is persuasive, says , director of the Center for Systems Neuroscience at Boston University, who was not involved in the study.
"It was compelling enough that I thought, 'Maybe I need to be doing this,'" he says.
The result backs earlier in animals showing that environments that stimulate the brain can increase levels of certain neurotransmitters. Studies of people have suggested that cognitive training can .
Never skip brain day
The study, funded by the National Institutes of Health, comes amid a proliferation of online brain-training programs, including Lumosity, Elevate, Peak, CogniFit and BrainHQ.
But it has been hard to know whether these programs really work, says de Villers-Sidani, who directs the cognitive disorders clinic at McGill's Montreal Neurological Institute.
"They had a positive impact on some cognitive measures," he says, "but then the question was, how much is it changing the brain and how is it changing the brain?"
So de Villers-Sidani and a team of researchers decided to see whether mental exercise could increase levels of acetylcholine, a neurotransmitter that's closely associated with cognitive performance.
Acetylcholine levels typically begin a gradual decline around middle age. The levels drop sharply, though, in people with Alzheimer's disease.
The team studied 92 healthy people who were 65 or older.
Half the participants spent 30 minutes a day playing computer games like solitaire and Candy Crush.
The others spent the same amount of time each day doing cognitive exercises that are part of the scientifically tested program BrainHQ. The program challenges users to remember the type and location of items that appear and disappear with increasing speed.
"It's really targeted at attention and speed of processing, and it kind of pushes you to the limit," de Villers-Sidani says.
The researchers used a to detect changes in acetylcholine levels in the anterior cingulate cortex, a brain region that's important for making decisions and detecting errors.
"I was not sure we would find anything, to be honest," de Villers-Sidani says.
But they did. In people who played games like solitaire, acetylcholine levels were unchanged. But in people who did cognitive training, there was a significant increase.
Acetylcholine levels also increased in other brain areas, including the hippocampus, which plays a key role in memory.
Even modest changes are meaningful, Hasselmo says, because acetylcholine does more than carry messages in the brain. It also modulates the behavior of neurons in ways that affect learning, memory and attention.
So when a person takes, say, a high dose of the motion sickness drug scopolamine — which blocks the effects of acetylcholine — things start to go awry.
"If you block the neuromodulator function in the brain, a person can't even think," Hasselmo says. "You go into a delirious state."
On the other hand, even small increases in acetylcholine can have a "profound and notable effect" on memory and thinking in older people.
Hasselmo notes that the reduced symptoms by increasing levels of acetylcholine. Now, he says, intensive brain training has the potential to achieve similar gains and stave off cognitive decline.
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