With more than 5.3 million Americans living with dementia – a number that escalates annually — there’s a very real fear that the disease will rob the golden years of their glow. There is hope, though. Recent studies suggest that the most common form, Alzheimer’s, can be slowed by exercise.

This year, a new study from the Rush University Medical Center in Chicago showed that high levels of the gene called brain-derived neurotrophic factor (BDNF). may be key to slowing development of Alzheimer’s. Dr. Aron Buchman’s team studied 535 people (average age 81) for an average of six years, testing their cognitive functions (thought processes and memory) each year. After their deaths, the researchers took note of the BDNF levels in the brain.

The study, published in Journal of Neurology, showed that exercise boosted BDNF levels. For subjects with the highest BDNF levels, there was a 50 percent slower loss of cognitive functions compared with persons with the lowest BDNF levels.

Still other papers and studies have made a connection between water exercise and a slowing of Alzheimer’s progression. For example, “Exercise and Dementia” (2015) by Stan Reents, PharmD, cited a study by University of Washington that followed 2,288 patients age 65 and older for six years. UW researchers found that individuals who exercised three times a week for at least 15 minutes developed dementia at a lower rate than those who exercised less. Swimming and water aerobics were among the beneficial exercises named.

An Australian study involving 10 adults (average age 88) living in a nursing home showed that a twice-weekly, 12-week aquatic exercise program was beneficial for participants with moderate to severe dementia. Elsevier Inc.’s findings were published online in 2014 and showed that the subjects’ balance and physical movement increased in small to moderate amounts after water activity.

Finally, there’s the case of the 89-year-old man with advanced Alzheimer’s disease who showed remarkable improvement following aquatic therapy. The report, published in Annals of Long-Term Care in 2013, was the work of Kent Myers, MD; Dina Capek, RN; Holly Shill, MD; and Marwan Sabbagh, MD. Regular physical therapy had been tried for six weeks, and failed. Then the subject started aquatic therapy twice weekly for 30-minute sessions for three months. He went from being expressionless and exhibiting poor communication skills to smiling, speaking in sentences and following directions. The report stated that exercise has been shown to improve the physical functioning of elders with Alzheimer’s and to slow the rate of decline in the daily living activities of long-term care residents with dementia.