The study — which followed more than 2,800 older adults for a decade — reveals how the brain-training intervention known as "speed-of-processing training" reduced participants' risk of dementia by 29 percent.
The intervention was developed by Dr. Karlene Ball, of the University of Alabama at Birmingham, and Dr. Dan Roenker, of Western Kentucky University in Bowling Green, and the study results were recently published in the journal Alzheimer's & Dementia: Translational Research & Clinical Interventions.
Dementia is an umbrella term for a decline in cognitive functions — such as learning, memory, and reasoning — that impairs a person's ability to perform day-to-day tasks.
It is estimated that dementia affects around 47 million people worldwide. By 2030, this number is projected to soar to 75 million.
A wealth of research has indicated that people may protect themselves against cognitive decline and dementia through brain training.
Scientists now know that the brain can adapt to change at any age, and that such adjustments can be either beneficial or harmful. This process is known as "neuroplasticity." Brain training aims to strengthen neural connections in a way that maintains or increases cognitive functioning.
To investigate this association further, Drs. Ball, Roenker, and colleagues launched The Advanced Cognitive Training in Vital Elderly (ACTIVE) Study, which is the largest study of cognitive training to date.
The ACTIVE Study
Part-funded by the National Institutes of Health (NIH), the study included a total of 2,802 adults from the United States with an average age of 74.
Participants were randomized to one of three brain-training groups or to a control group, members of which did not receive cognitive training.
The first group was given instructions on strategies to help boost memory, the second received instructions on strategies to improve reasoning skills, and the third group received individual speed-of-processing training, which was developed by the researchers.
The speed-of-processing training is a task that aims to improve a user's visual attention — that is, the speed and accuracy with which a person can identify and remember objects in front of them.
The speed-of-processing training involves a computer game called "Double Decision," wherein the user is asked to spot an object, such as a car, in the center of their gaze, while also identifying an object in their peripheral vision, such as a road sign. As the game goes on, the user is given less time to spot each object, and distractors are added to the screen to make it more challenging.
During the first 6 weeks of the study, each brain-training group received 10 training sessions, each of which lasted for around 60–75 minutes. At 11 and 35 months, subsets of each brain-training group also received up to four "booster" training sessions.
All study groups underwent cognitive and functional assessments after the first 6 weeks, as well as at 1, 2, 3, 5, and 10 years. The incidence of dementia among the subjects over the 10-year follow-up was also assessed.
Dementia risk reduced by 29 percent
The researchers found that the incidence of dementia was highest among the control group, at 10.8 percent.
Among participants who completed at least 15 sessions of the memory and reasoning training, dementia incidence was 9.7 percent and 10.1 percent, respectively.
But subjects who completed the speed-of-processing training were found to have a significantly lower incidence of dementia, at 5.9 percent.
The team calculated that the speed-of-processing training resulted in a 29 percent reduced risk of dementia over 10 years, and that each additional training session was associated with a 10 percent lower dementia risk.
"When we examined the dose-response," notes lead study author Jerri Edwards, Ph.D., of the University of South Florida in Tampa, "we found that those who trained more received more protective benefit."
The researchers explain that speed-of-processing training has demonstrated significant benefits for cognitive function in 18 clinical trials to date. Combined with their latest results, the researchers are confident that this form of brain training can reduce the risk of dementia. The team says:
"We have shown that a specific form of cognitive training, speed-of-processing, reduced the risk of dementia in initially well-functioning older adults followed up to 10 years. This is the first report of an intervention significantly reducing dementia risk."
That being said, the researchers stress that further studies are needed to determine why speed-of-processing training is effective for cognitive functioning, while other forms of brain training are not.
"We also need to investigate what is the appropriate amount of training to get the best results. The timing of intervention is also important," adds Edwards.
"Existing data," he adds, "indicate speed training is effective among older adults with and without mild cognitive impairment, but it is important to understand this is preventative to lower risk of dementia and is not a treatment for dementia."
"Our ongoing research is examining this intervention among persons with Parkinson's disease as well as other types of cognitive interventions," Edwards concludes.