Study examines change in cognitive function following physical, mental activity in older adults

A randomized controlled trial finds that 12 weeks of physical plus mental activity in inactive older adults with cognitive complaints was associated with significant improvement in cognitive function but there was no difference between intervention and control groups, according to a report published Online First by JAMA Internal Medicine, a JAMA Network publication.

An epidemic of dementia worldwide is anticipated during the next 40 years because of longer life expectancies and demographic changes. Behavioral interventions are a potential strategy to prevent or delay dementia in asymptomatic individuals, but few randomized controlled trials have studied the effects of physical and mental activity together, according to the study background.

"We found that cognitive scores improved significantly over the course of 12 weeks, but there were no significant differences between the intervention and active control groups. These results may suggest that in this study population, the amount of activity is more important than the type of activity, because all groups participated in both mental activity and exercise for [60 minutes/per day, three days/per week] for 12 weeks. Alternatively, the cognitive improvements observed may be due to practice effects," the authors note.

The study by Deborah E. Barnes, Ph.D., M.P.H., of the University of California, San Francisco, and colleagues included 126 inactive, community-dwelling older adults with cognitive complaints. All the individuals engaged in home-based mental activity (1 hour/per day, 3 days/per week) plus class-based physical activity (1 hour/per day, 3 days/per week) for 12 weeks and were assigned to either mental activity intervention (MA-I, intensive computer work); or mental activity control (MA-C, educational DVDs) plus exercise intervention (EX-1, aerobic) or exercise control (EX-C, stretching and toning). The study design meant there were four groups: MA-I/EX-I, MA-I/EX-C, MA-C/EX-1 and MA-C/EX-C.

Global cognitive scores improved significantly over time but did not differ between groups in the comparison between MA-I and MA-C (ignoring exercise), the comparison between EX-I and EX-C (ignoring mental activity), or across all four randomization groups, according to the study results.

"The prevalence of cognitive impairment and dementia are projected to rise dramatically during the next 40 years, and strategies for maintaining cognitive function with age are critically needed. Physical or mental activity alone result in small, domain-specific improvements in cognitive function in older adults; combined interventions may have more global effects," the study concludes.

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Why Do We Blink So Frequently?

We all blink. A lot. The average person blinks some 15-20 times per minute—so frequently that our eyes are closed for roughly 10% of our waking hours overall.

Although some of this blinking has a clear purpose—mostly to lubricate the eyeballs, and occasionally protect them from dust or other debris—scientists say that we blink far more often than necessary for these functions alone. Thus, blinking is physiological riddle. Why do we do it so darn often? In a paper published in the Proceedings of the National Academy of Sciences, a group of scientists from Japan offers up a surprising new answer—that briefly closing our eyes might actually help us to gather our thoughts and focus attention on the world around us.

The researchers came to the hypothesis after noting an interesting fact revealed by previous research on blinking: that the exact moments when we blink aren’t actually random. Although seemingly spontaneous, studies have revealed that people tend to blink at predictable moments. For someone reading, blinking often occurs after each sentence is finished, while for a person listening to a speech, it frequently comes when the speaker pauses between statements. A group of people all watching the same video tend to blink around the same time, too, when action briefly lags.

As a result, the researchers guessed that we might subconsciously use blinks as a sort of mental resting point, to briefly shut off visual stimuli and allow us to focus our attention. To test the idea, they put 10 different volunteers in an fMRI machine and had them watch the TV show “Mr. Bean” (they had used the same show in their previous work on blinking, showing that it came at implicit break points in the video). They then monitored which areas of the brain showed increased or decreased activity when the study participants blinked.

Their analysis showed that when the Bean-watchers blinked, mental activity briefly spiked in areas related to the default network, areas of the brain that operate when the mind is in a state of wakeful rest, rather than focusing on the outside world. Momentary activation of this alternate network, they theorize, could serve as a mental break, allowing for increased attention capacity when the eyes are opened again.

To test whether this mental break was simply a result of the participants’ visual inputs being blocked, rather than a subconscious effort to clear their minds, the researchers also manually inserted “blackouts” into the video at random intervals that lasted roughly as long as a blink. In the fMRI data, though, the brain areas related to the default network weren’t similarly activated. Blinking is something more than temporarily not seeing anything.

It’s far from conclusive, but the research demonstrates that we do enter some sort of altered mental state when we blink—we’re not just doing it to lubricate our eyes. A blink could provide a momentary island of introspective calm in the ocean of visual stimuli that defines our lives.