New research provides compelling evidence that maintaining physical fitness in older age is strongly linked to healthier brain aging and reduced risk of cognitive decline.
A study published December 10 in the British Journal of Sports Medicine demonstrates that better cardiorespiratory fitness is associated with improved cognitive performance in older adults, even among those with genetic predisposition to Alzheimer's disease.
Researchers led by Kirk Erickson, director of translational research at AdventHealth Research Institute, evaluated nearly 650 cognitively healthy seniors aged 65 to 80. Participants underwent comprehensive cardiorespiratory fitness testing using a graded treadmill protocol, along with extensive cognitive assessments conducted over two days.
"We found that cardiorespiratory fitness, which predicts the onset of numerous diseases and can be modified by regular exercise, was positively associated with cognitive performance across all domains assessed," the research team reported.
The cognitive tests measured five distinct areas of brain function: processing speed, short-term working memory, long-term episodic memory, planning and organizational skills, and visual-spatial interpretation abilities.
While performance in all cognitive domains declined with age as expected, individuals with superior cardiorespiratory fitness demonstrated better cognitive function across all areas compared to less fit counterparts, regardless of age or presence of the APOE4 gene—a known risk factor for Alzheimer's disease.
Gender and Educational Differences
Interestingly, the relationship between fitness and cognitive function was more pronounced in women than men, particularly in processing speed and planning abilities. The association was also stronger among participants with fewer years of formal education and those taking beta blockers for hypertension.
The researchers noted that the protective effect of cardiorespiratory fitness among those with less education is particularly significant, as lower educational attainment has previously been linked to greater risk of cognitive decline and dementia.
"These findings, if replicated, suggest that the presence of one protective factor [e.g., higher cardiorespiratory fitness] could attenuate the lack of another [e.g., few years of education]," the researchers wrote.
Muscle Preservation Also Critical for Brain Health
In a complementary study presented December 3 at the Radiological Society of North America's annual meeting, researchers from Johns Hopkins University School of Medicine found that maintaining muscle mass may also be crucial for preserving cognitive function.
"We found that older adults with smaller skeletal muscles are about 60% more likely to develop dementia when adjusted for other known risk factors," said study co-senior author Marilyn Albert, professor of neurology at Johns Hopkins.
The research team examined brain scans of 619 individuals with an average age of 77, focusing on the temporalis muscle, which helps move the jaw and serves as an indicator of overall skeletal muscle status throughout the body.
Participants with smaller temporalis muscles showed significantly higher rates of Alzheimer's disease diagnosis, memory issues, reduced functional activity, and decreased brain volume compared to those with larger muscles.
Potential Mechanisms and Implications
Scientists believe cardiorespiratory fitness may benefit brain health through multiple pathways, including improved cerebral blood flow, stimulation of neurogenesis, enhancement of neural connections, and optimization of brain chemical systems.
Additional factors associated with better fitness—such as improved mood, reduced fatigue, and better sleep quality—may further contribute to cognitive protection.
Dr. Shadpour Demehri, professor of radiology at Hopkins and co-senior author of the muscle study, emphasized that interventions like weight training and dietary modifications can help slow muscle loss.
"These interventions may help prevent or slow down muscle loss and subsequently reduce the risk of cognitive decline and dementia," Demehri noted.
A Comprehensive Approach to Brain Health
Taken together, these studies suggest that a comprehensive physical fitness regimen incorporating both aerobic exercise and strength training may provide optimal protection against age-related cognitive decline.
The researchers emphasized that cardiorespiratory fitness and muscle maintenance represent important modifiable health factors and potential therapeutic targets for preserving cognitive function in late adulthood.
As the global population ages and dementia rates continue to rise, these findings offer promising evidence that lifestyle interventions focused on physical fitness may play a crucial role in maintaining brain health throughout the lifespan.
