HealthNotes

• By Suzanne Dixon, MPH, MS, RD

Exercise Gives the Brain a Boost

In the United States, the population of people 65 and older has increased by about 16% since 1990, while the “oldest old,” those 85 and up, has increased by an incredible 42%. About 10% of people 65 and older are affected by Alzheimer’s disease and up to half of those 85 and up have the disease.

The intersection of these trends means that many millions of people will struggle with thinking (cognitive) decline in the coming years. Anything that can be done to lessen this burden of disease is welcome news. It turns out exercise may be just the ticket.

We all need to exercise regularly for optimum health, but physical activity may be particularly beneficial for the aging female brain

Women benefit greatly

To study the effects of exercise on cognitive function, researchers randomly selected 33 senior men and women (average age 70) to complete a six-month exercise program. Study subjects participated in four supervised weekly sessions of either high-intensity aerobic activity or a stretching program.

Blood samples were collected and analyzed for various markers of health, such as insulin, the “stress hormone” cortisol, and blood sugar (glucose) levels. Aspects of cognitive and higher brain (“executive”) function, such as memory, verbal fluency, and the ability to learn a list were measured.

After six months, the researchers found that:

• Men and women in the aerobic exercise group had similar gains in cardiovascular and respiratory (cardiorespiratory) fitness and body fat reduction.
• Women in the aerobic exercise group improved performance on multiple tests of executive function, improved their body’s ability to manage glucose, and reduced blood levels of insulin, cortisol, and another measure of decline in cognitive function (brain-derived neurotrophic factor).
• Men in the aerobic exercise group did not show improvement in most blood markers or on all but one of the tests of cognitive function.

The researchers noted that the aerobic exercise benefits were greatest for women in the preclinical stages of Alzheimer’s disease, when cognitive impairment is mild.

Putting it into practice

We all need to exercise regularly for optimum health, but physical activity may be particularly beneficial for the aging female brain. To stay sharp, keep the following points in mind:

• Participants in this study exercised at 75% to 85% of heart rate reserve for 45 to 60 minutes, four times per week.
• Heart rate reserve is the difference between your maximum heart rate and your resting heart rate.
• To calculate your maximum heart rate, subtract your age from 220. Your resting heart rate is your pulse (heart beats per minute), taken when you are at rest.
• To get 75% to 85% of your heart rate reserve, multiple your heart rate reserve by 0.75 and by 0.85. The resulting two numbers give you a range for how many beats per minute your heart should be beating during exercise.
• If math is not your thing, ask your doctor to help you figure out an appropriate exercise level for you. You can ask about this when you are checking in with your doctor to make sure it is safe for you to begin an exercise program.

(Arch Neurol 2010;67:71–9)