This month brought a few studies showing some interesting connections between our everyday habits and cognition—dehydration, digital devices, and (potentially) neckties may all apparently sap cognitive bandwidth. The good news is that these habits are easily fixable (although device use may be trickier), which points to how delicate, and how responsive to its surroundings, the human brain can be. The three new studies are outlined below, along with four longer-term habits that may also deplete or replenish brain power. Again, some are easier to address than others, but the ones that take a little more commitment are definitely worth it, considering what’s at stake.
As mentioned, a study earlier this month found that being just a bit dehydrated can affect cognition. The researchers analyzed previous studies, arriving at a final pool of 33 that looked at how being dehydrated at various levels can affect cognitive performance. Generally, the team found that people started making some errors during attentional tasks earlier during dehydration, and the errors became more pronounced the more significant the dehydration. In addition to the more innocuous initial errors, higher-level capacities like math and logic also fell off with dehydration over 2% of one’s body mass (which could occur after working out for a few hours without drinking).
“The simplest reaction time tasks were least impacted, even as dehydration got worse, but tasks that require attention were quite impacted,” said study author Mindy Millard-Stafford in a statement. Being dehydrated could well affect the kinds of attention and executive functions that’s required in work, school, or leisure. “Maintaining focus in a long meeting, driving a car, a monotonous job in a hot factory that requires you to stay alert are some of them,” said Millard-Stafford.
People working in hot places who need to make technical decisions would probably by the most affected—but for people who are feeling a little groggy, thinking back on whether you’ve gone a big chunk of the day without hydrating may be wise.
Another study this month found that wearing a necktie can cut off the circulation to your brain—not fully, of course, but by about 7%. The team, wishing to study “socially desirable strangulation,” had men don neckties or go without, and then undergo MRI scans to measure cerebral blood flow. Men whose ties were tightened had a significant loss of the blood flow to their brains compared to others.
Whether this loss of blood flow would be enough to affect cognition isn’t totally clear. But for men who are concerned about the possibility, it may not be the worst idea to wear your tie a bit looser.
Devices in the classroom
Cell phones are likely the bane of many teachers’ existence these days, and now they have a true scientific study to support banning them. Researchers at Rutgers University allowed half of the study’s participants—funnily enough, 118 Rutgers cognitive psychology students—to use cell phones, tablets, and laptops in the classroom, and banned their use for the other half. The team correlated the students’ grades throughout the semester with their use of devices, and found that the kids for whom devices were banned had final grades that were about half a grade (or 5%) higher than the kids who got to use them.
“These findings should alert the many dedicated students and instructors that dividing attention is having an insidious effect that is impairing their exam performance and final grade,” said Arnold Glass. “To help manage the use of devices in the classroom, teachers should explain to students the damaging effect of distractions on retention – not only for themselves, but for the whole class.”
Others have suggested that gadgets are “making us dumb” for a variety of reasons, but this is the first to show a causal connection between their use and academic performance. The same connection is very likely true for devices in the office—and at home, when you’re trying to have some quality time with your family.
Another habit worth mentioning, given its potentially significant effects on cognition, is one that most people don’t get enough of, acutely or chronically: Sleep. Losing sleep on a chronic level can affect cognition, but so can just a night or two of poor sleep.
A study last year looked at brain cells and cognition in real time: It found that during a night of lost sleep, participants’ brain cells became slower to respond during a cognitive task, and when they did respond, their activity was sloppier than normal. And sleep loss over the long-termhas been shown to affect our cognition and our ability to form memories.
Sleep isn’t just an indulgence, but a necessary habit during which the brain is doing a lot of heavy work—pruning unnecessary connections and strengthening the needed ones. Most people know from their own anecdotal evidence that lost sleep can seriously affect how well we think and make decisions, but the scientific evidence certainly backs that up as well.
Like sleep loss, stress affects just about every system in our bodies; and chronic stress is well-known to affect our mental prowess. Likely due to the stress hormone cortisol and its inflammatory effects, stress has been shown to affect everything from memory formation to decision-making to hand-eye coordination to brain volume. While we may not be able to control every variable that presents stress in our lives, we can at least control our relationship to the stress and how we respond. Taking care of ourselves, using tools like meditation, yoga, and therapy are good ways to reduce the effects that stress is known to have.
Lack of Social Connection
Social connection—and its doppelganger, loneliness—has been shown again and again to have major impacts on our health and mental health. In fact, social connectivity keeps showing up in the research as perhaps the number one variable affecting long-term health. And loneliness has been linked to poorer cognition, especially in older people. A study a few years ago showed that loneliness and social isolation were linked to a greater risk of cognitive decline in the future. It’s not totally clear why this is, but it may be the intellectual and emotional stimulation, not to mention stress reduction, which social interaction provides.
Finally, sugar is one “food” that’s been shown to have ill effects on our neurological and cognitive health (“sugar coma” is a pretty well-known phenomenon, and there’s some logic to it). Not only does sugar seem to function somewhat like a drug, but it’s been shown to sap mental resources: A study a few years ago found that rats who were given sugar-water instead of plain water performed more poorly on a memory task (interestingly, those who were given omega-3s in addition to sugar water performed fine, suggesting that omegas may counter the effects of sugar). And it’s not just rodents: A study earlier this year found that people who consumed either glucose or sucrose performed worse on cognitive tests than those who consumed fructose or placebo—which isn’t surprising given the known connection between sugar and Alzheimer’s disease.
These are just a few variables that affect cognition, and there are certainly others that aren’t so easy to change—like chronic financial stress. Studies have found that poverty can take a toll on a person’s cognition that’s equivalent to a 13-point drop in IQ, and this is true across the globe. As mentioned, we can’t always change all the variables that deplete our cognitive resources—but we can certainly start to do what we can to shift some of the more changeable ones. Diet and sleep may take some work, but it’s definitely worth it. In the meantime, have a glass of water, loosen your necktie, and put the phone way—and see if you don’t feel a little more clear-minded as a result.