Buzz
Certain actions are known to reduce cognitive abilities. It's unlikely you'll perform your best on an intelligence test after a few shots of tequila or hits from a bong. Repeatedly slamming your head into a wall isn't likely to boost mental processing either.
However, there are also lesser-known factors that can affect brain function. Some of these only have a temporary impact, while others are proven to cause lasting effects.
10. Poor Lighting
Researchers from Michigan State University have found a connection between dim lighting and a reduced ability to remember and learn.
The scientists examined the brains of a group of Nile grass rats. Like humans, these rats are active during the day and rest at night. Initially, the rats were trained to navigate a maze. Then, they were divided into two groups: one exposed to bright light during the day and the other to dim lighting.
After four weeks, the rats exposed to only dim lighting experienced a 30 percent reduction in hippocampus capacity, a key area for learning and memory. When the rats were placed back in the maze they had trained on, those exposed to dim light performed worse than before, while those in bright light showed notable improvement.
The dim lighting used in this experiment resembles the typical indoor lighting found in most homes and offices.
9. Smartphones
Smartphones keep us connected at all times, but this constant connectivity comes at the expense of our cognitive abilities.
A study by the University of Texas involved around 800 smartphone users. Participants took a series of computer tests that required undivided attention. Some were asked to leave their phones in another room, while others were told to mute their devices and place them face down on their desks. Those who kept their phones in another room performed much better than those who kept their phones nearby.
The researchers concluded that simply having a phone in view reduces a person’s ability to focus and perform tasks. People are so used to checking their phones that their subconscious mind constantly battles this urge while they try to focus on other things.
This mental effort to avoid the temptation of checking the phone drains energy and focus that could otherwise be directed toward the task at hand. Removing the phone entirely gives the subconscious a chance to rest from resisting the urge to check for new texts or emails.
8. Processed Foods
A poor diet early in life has been linked to negative effects on cognitive performance. Researchers studied the eating habits and intelligence levels of around 14,000 young children. Those who primarily ate processed foods at age three had lower average IQs five years later compared to those who ate diets rich in vitamins and nutrients.
A diet rich in vitamins and nutrients supports optimal brain development, while processed foods do not. Since the brain develops most rapidly in the first three years of life, the nutrition provided during this period has a long-lasting impact on overall brain function.
For children who were primarily fed processed foods at age three, improvements in their diet later on had little effect on boosting their intelligence scores.
7. Multitasking
Numerous studies have shown that multitasking is ineffective. The brain is incapable of concentrating on more than one task at once. This means the brain rapidly shifts focus back and forth when multitasking, leading to poorer performance on tasks compared to focusing on one at a time.
Despite this, many people claim to be skilled at multitasking, prompting researchers to wonder if some individuals are naturally better at it. A team from Stanford University interviewed participants about their perception of their multitasking abilities and then tested their actual performance.
The results revealed the opposite. People who believed they were excellent at multitasking performed worse at managing multiple tasks than those who preferred focusing on one thing at a time.
Multitasking not only leads to lower performance, but it can also cause a temporary decline in IQ. A study from the Institute of Psychiatry in London found that multitasking resulted in a 10-point drop in IQ, a greater decrease than what was observed after smoking marijuana or missing a full night's sleep.
6. Sugar
A diet rich in fructose leads to a decrease in intelligence after just six weeks.
Researchers at the University of California, Los Angeles, investigated the impact of a high-fructose diet on rats. The rodents were trained to navigate a maze before being divided into two groups. Both groups received fructose-laced water, but one group was also given omega-3 fatty acids, believed to protect brain cells from damage.
After six weeks, the rats that received omega-3 fatty acids performed much better in the maze compared to those that did not. The rats without omega-3 fatty acids showed reduced synaptic activity and struggled to remember the route they had previously learned.
High fructose intake altered the rats' insulin levels. Brain cells rely on sugar as energy. A constant supply of fructose impacts how brain cells store and use this sugar, influencing their ability to process thoughts and emotions.
Fortunately for sugar enthusiasts, omega-3 fatty acids have been shown to prevent brain cell damage caused by fructose, meaning a piece of salmon after a bowl of ice cream can help keep your IQ from dropping.
5. A Long Commute
Commuting for more than two hours a day steadily reduces IQ. Researchers at the University of Leicester studied the lifestyles of over 500,000 individuals for five years, testing their memory and intelligence throughout the research.
Of the participants, 93,000 drove for more than two hours each day. These individuals scored lower at the start of the study compared to those who drove little or not at all. Furthermore, the long-distance commuters experienced a gradual decline in cognitive abilities over the study period.
The brain is less active while driving, and the lack of mental stimulation is believed to contribute to the decline in IQ. Similar effects are seen in individuals who watch more than three hours of television daily.
4. Jet Lag
Jet lag may leave you feeling off for a few days, but its impact on memory and learning can last much longer than you might expect.
Researchers at the University of California, Berkeley, examined the effects of chronic jet lag in hamsters, as these creatures are an ideal model for studying circadian rhythms. Twice a week for a month, the researchers shifted the hamsters' schedules by six hours to replicate the experience of an international flight and time zone change.
The hamsters were tested on memory and learning tasks both during the jet lag simulation and one month after they had returned to a normal sleep schedule. As anticipated, their performance was poor during the jet lag simulation. The hamsters suffering from jet lag struggled to learn simple tasks that those on a normal sleep schedule completed with ease.
Even after a month of returning to their regular sleep patterns, the hamsters still performed poorly on memory and learning tests. Further analysis revealed that the hamsters exposed to the altered sleep schedule had only half the number of neurons in their hippocampus compared to the control group. This hippocampal deficiency persisted weeks after the hamsters had resumed their normal routine.
In addition to frequent international travelers, anyone who regularly alters their sleep schedule, such as those working rotating third shifts, would also experience damage to the hippocampus.
3. Dumb TV Shows
Studies have shown that when it comes to intelligence, your viewing habits have an impact.
While some television shows provide useful information, many others are devoid of educational value. In addition to being shallow, these mindless shows have been shown to actively lower people's cognitive abilities.
Markus Appel, an Austrian psychologist and professor, conducted a study with a group of college students across several subjects. Before the test, half of the students were given a story about a foolish man making a series of poor decisions. After reading about the character's silly antics, these students scored lower on the tests than those who hadn't read the story.
Appel attributes the results to what he calls 'media priming.' Media priming refers to the lingering, often unintended, effects of media exposure, which can influence behavior, opinions, and even intelligence.
In other words, watching a reality TV show featuring a particularly foolish person might be amusing, but their lack of smarts is contagious.
2. Being Spanked As A Child
A study conducted on children in the US revealed that children who had been spanked exhibited lower IQs compared to their peers who had not been spanked.
Researchers assessed the cognitive abilities of two groups of children, one between the ages of two and four and the other between five and nine. Four years later, the same children were retested.
In the older group, children who had been spanked showed an average IQ nearly three points lower than those who hadn’t been spanked. Among the younger group, the difference was even more pronounced, with those who were spanked scoring five points lower than their counterparts.
Global data also indicated that countries where spanking was more common tended to have a lower average IQ.
One theory for the connection between spanking and lower IQ is stress. Researchers suggest that corporal punishment can serve as a chronic stressor, leading children to be easily startled and more fearful, traits that are linked to reduced cognitive ability.
Corporal punishment rates have been declining worldwide, and scientists predict this trend will result in a global increase in average IQs.
1. Obesity
Excessive body fat impacts the functioning of all our organs, including the brain.
A study on 17 obese women found that their brains metabolized sugars more quickly than women of average weight. These women were tested on cognitive abilities before and after undergoing bariatric surgery.
After the weight-loss surgery, the women showed significant cognitive improvements, especially in executive functions, which involve tasks like planning and organization.
Obese individuals process sugars differently than those without excess body fat. This altered processing is believed to cause structural damage in the brain, ultimately affecting cognitive performance.
In a study involving nearly 500 adults, researchers found that overweight individuals had less white matter than their peers with average body size.
White matter plays a crucial role in connecting different brain areas and facilitating communication between them. While all humans naturally lose white matter with age, overweight individuals experience this deterioration at a faster rate.
The white matter volume of a 50-year-old obese person was similar to that of a 60-year-old person with a normal weight. Interestingly, this difference in white matter was only observed in those who were middle-aged or older, suggesting that we may be more susceptible to white matter loss during this stage of life.
