What Lowers IQ: 7+ Factors That Can Affect Your Intelligence

Stress, unhealthy eating and sleep patterns, and substance abuse are just some of the answers to what lowers IQ. The truth is that while IQ scores are relatively stable throughout life, certain factors can lead to their decline over time.

Fortunately, there are ways to turn things around, whether the cause lies in poor habits and lifestyle choices or underlying health issues that affect cognitive function.

In this article, we’ll list the most common—and some less obvious—reasons for a drop in IQ. Additionally, we’ll offer tips on how to counteract these factors to improve brain health, including insights into what increases IQ.

Let’s begin!

Key Takeaways

• IQ, or intelligence quotient, is a measure of cognitive ability derived from a standardized IQ test.
• Knowing what lowers IQ can help you make better lifestyle choices and improve your mental and physical health.
• IQ can reduce over time due to poor diet, excessive stress, sleeping problems, and substance abuse, among other factors.
• Habits that lower IQ can be turned around with conscious effort and positive lifestyle changes, such as exercising and engaging in mind-challenging activities.

What is IQ, and How is It Measured?

IQ stands for intelligence quotient, a score derived from a standardized IQ test designed to evaluate cognitive development. It’s calculated by measuring various factors that affect cognitive development, such as problem-solving abilities, abstract thinking, logical reasoning, memory, and attention span.

The “standardized IQ test” is an umbrella term for several internationally recognized intelligence assessment tools. They include the Stanford-Binet Intelligence Scale, Wechsler Adult Intelligence Scale, Differential Ability Scales, and Raven’s Progressive Matrices.

These tests use advanced psychometric methods to measure cognitive development by comparing the test taker’s performance to that of their peer group. The results are then expressed as percentiles and converted to an equivalent score on the Stanford-Binet scale ranging from 40 to 160.

For example, if you do equally well as half of your peers, you’re in the 50th percentile, meaning you have an average IQ of 100.

Similarly, if your performance surpasses 95% of your peer group, you belong to the 95th percentile. This is an impressive result because it means you have a high IQ of 125.

What Lowers IQ and 8 Effective Ways You Can Fix It

The answer to what lowers IQ is multifaceted, as it includes several factors, ranging from excessive sugar intake to substance abuse.

Let’s examine these factors in detail and see how you can fix the damage they cause.

#1. Consuming Excessive Amounts of Sugar

One of the lesser-known culprits behind cognitive decline is excessive sugar consumption. While it may provide a quick burst of energy, too much sugar can wreak havoc on your brain in the long run.

The reason is that high sugar intake leads to insulin resistance, reducing the brain’s ability to process and store information. Over time, this can even contribute to memory loss and lower IQ.

However, this doesn’t mean you have to renounce sweets completely—the key is moderation. Cutting back on sugary snacks and drinks can help stabilize blood sugar levels, which in turn benefits brain health.

Try swapping sweets for foods rich in healthy fats and antioxidants, like nuts and seeds. Additionally, opt for whole foods such as fruits, vegetables, and whole grains, as they release energy more slowly and provide essential nutrients for brain function. Staying hydrated by drinking water or unsweetened herbal teas can also help your brain work at its peak.

These small changes in your diet can do wonders in avoiding factors that lower IQ and keep your mind sharp for the long haul.

#2. Being Too Stressed

Stress is an inevitable part of life—we’re all bound to experience it from time to time. That said, being too stressed can seriously harm your cognitive abilities. Namely, chronic stress triggers the release of cortisol, a hormone that, in excess, can interfere with memory, focus, and decision-making.

Prolonged exposure to stress can lower IQ and quickly shrink the hippocampus—the brain area responsible for learning and memory.

Unsurprisingly, relaxing is the best way to deal with stress. In fact, there’s a proven positive correlation between IQ and meditation, one of the best cures for stress. That said, even a simple breathing exercise or a short walk outside can go a long way in lowering cortisol levels.

Another excellent stress-buster is physical activity, as it promotes the release of endorphins—natural mood boosters. Still, doing it can result in burnout, so it’s important that you remember to take some time every day to unwind.

By finding healthy ways to handle stress, you can prevent it from taking a toll on your cognitive health and enhance your ability to think clearly under pressure.

#3. Multitasking

Nowadays, multitasking is almost presented as a superpower—everyone tends to admire those who can take on multiple responsibilities at once. However, as it turns out, multitasking can actually do more harm than good when it comes to cognitive performance.

When you juggle tasks, your brain constantly switches focus, which lowers productivity and affects memory retention. Splitting attention like that makes it harder to concentrate, and over time, it can lower the quality of your work as well as your IQ.

The solution to this problem is obvious—try focusing on one thing at a time. This way, you’ll complete tasks more efficiently and with better results. For example, you can break down large pieces of work into smaller, more manageable steps and give yourself time to complete each one without distractions.

Techniques like the Pomodoro method can be quite helpful here, too—work for a set period, then take a short break to stay focused.

By training yourself to resist the urge to multitask “for the sake of saving time,” you’ll sharpen your cognitive abilities and stay on top of your game.

#4. Poor Sleep

It’s no secret that poor sleep is harmful to health, both physical and mental, but you may not know just how closely IQ and sleep are connected. Namely, sleep deprivation can impair your attention span and working memory, among other cognitive functions, directly affecting your IQ. After all, sleep is the time when your brain processes information and recharges.

Without a good night’s sleep, you can find it hard to concentrate and react. If this goes on, it can result in a decline in cognitive performance.

To prevent these issues, establish a consistent sleep schedule. As an adult, you should aim for seven to nine hours of sleep each night. Additionally, try to steer clear of stimulants like caffeine or social media before bedtime. Creating a relaxing bedtime routine can help signal to your brain that it’s time to wind down.

Don’t underestimate the power of sleep—it’s one of the simplest yet most effective ways to keep your brain functioning at its best. With consistent, restful sleep, you can maintain mental sharpness and avoid what lowers IQ in the long run.

#5. Substance Abuse

Substance abuse, whether it’s alcohol or drugs, can have a severe impact on cognitive function. It can damage brain cells, impair memory, and reduce cognitive flexibility. What lowers IQ dramatically is the long-term use of these substances, which can lead to memory loss, difficulty concentrating, and slower cognitive processing.

The best way to fix this is, of course, to stop (or not start) using harmful substances. However, if you’re struggling with addiction and feel the problem is out of your hands, seeking professional help is the crucial first step.

Naturally, surrounding yourself with a strong support system of family and friends can also make all the difference in overcoming these challenges. Moreover, staying physically active and maintaining a healthy lifestyle can help your brain recover.

All in all, if you eliminate substance abuse from your life, you can protect your cognitive abilities and enhance overall brain health.

#6. Sedentary Lifestyle

Living a sedentary lifestyle—spending too much time sitting or being inactive—doesn't just affect your figure but also your brain. Physical activity is essential for maintaining blood flow to the brain, promoting the growth of new neurons, and reducing the risk of cognitive decline.

What decreases IQ, in this case, is the lack of stimulation for both the body and mind, which can lead to slower mental processing and poorer memory over time.

To counter this, include exercise in your daily routine. You don’t have to run marathons—activities such as speed walking, yoga, or even dancing can do wonders for your brain health. Exercise also boosts the production of brain-derived neurotrophic factor (BDNF), a protein that supports brain cell growth and repair.

If you don’t have a habit of exercising, you can start by taking short activity breaks during the day. For example, if you work at a desk, try standing and stretching every half an hour. Staying active won’t only improve your physical health but also keep your brain sharp and your IQ intact.

#7. Overexposure to Digital Media

Spending hours scrolling through social media or binge-watching shows is a common guilty pleasure nowadays. It may seem harmless, but overexposure to digital media can lower your attention span and reduce critical thinking skills.

Unfortunately, this habit often consumes the time that could be spent on intellectually stimulating activities, leading to mental stagnation. What lowers IQ in this scenario is the constant storm of information that chips away at your brain’s ability to process information deeply.

The only solution is self-control—set a specific time for digital media and balance it with activities like reading, puzzles, or creative hobbies. Moreover, you can practice “digital detox,” where you completely disconnect from screens, especially before bedtime.

That said, there’s a healthier way to use digital media—choose what to watch and read instead of mindlessly scrolling. There are various educational videos and thought-provoking articles online that can inspire you, so focus on those instead.

#8. Social Isolation

Prolonged social isolation can take a toll on your mental abilities. After all, no man is an island. Regular social interaction stimulates the brain, promoting emotional intelligence, problem-solving skills, and memory.

On the other hand, long-term loneliness can lead to cognitive decline and even increase the risk of dementia. The reason is the lack of opportunities for meaningful conversations that go hand in hand with interacting with others.

To combat this, you need to make a conscious effort to stay connected. You can take up a hobby where you get to meet new people or simply schedule regular get-togethers with friends. Attending community events and volunteering are also great ways to stay in touch with the world around you.

That said, you may be an introvert who finds all this overwhelming and even draining. In this case, it’s important to remember that you can socialize on your own terms—even a casual chat with a neighbor can make a difference. By staying socially active, you’ll stimulate your brain and protect yourself from the cognitive risk of isolation.

Take this free test to get accurate results

After adopting healthier habits to boost your IQ score, you can track your cognitive progress using our free IQ test.

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Final Thoughts

Poor nutrition, lack of sleep, and chronic stress are some examples of what lowers IQ naturally over time. While these factors may seem small, they can have a snowball effect on your cognitive functions in the long run.

The good news is that with conscious lifestyle changes, such as improving diet, exercising, and prioritizing sleep, it’s possible to reverse some of this decline.

Additionally, by knowing what contributes to low IQ, you can make more informed choices to protect and even boost your cognitive abilities as you age.