Have you ever walked into your kitchen and immediately forgot what you went to do there? Or the names of some of your middle school classmates aren't coming to mind as fast as you would like. Of course, you'll probably say to yourself, "There is no way this would happen to me when I was 20."
As humans, we rely on different aspects of intelligence and cognitive abilities to perform diverse daily tasks. However, depending on our age, we can't help but notice that our responses to situations are either getting enhanced or slowly declining.
Conventional wisdom agrees that our IQ does change with age. But is age the only reason to blame for declining intelligence and cognitive abilities? Do these changes make significant changes to your IQ score?
You may want to read our article on what intelligence is and the various types of intelligence out there before we proceed to explore the topic in-depth.
What Is IQ, And How Is It Measured?
IQ stands for intelligence quotient. It's a standard score that shows your relative intelligence compared to others in your age group. An IQ score is derived from a series of standardized intelligence tests measuring cognitive abilities like working memory, visual-spatial processing, and abstract thinking. Your scores for these tasks determine your IQ score.
IQ scores are typically centered around an average of 100. Most global IQ lies in the average IQ category between 85 and 115, and a smaller percentage falls below or above the average.
IQ scores have historically been used to predict educational achievement, job performance, and economic success. However, one of the lesser-discussed aspects of IQ is how it changes over a person's lifetime.
Let's delve into the old-age question: does IQ really change with age?
Does IQ Change With Age?
Recent findings have emerged showing that the cognitive abilities that make our IQ scores and other measures of general intelligence change with age. Additionally, life experiences and different ages also influence changes in IQ - whether positive or negative.
For instance, studies on children in early and late adolescence have found that children can raise their IQ by as much as 20 points. That's why short-term memory and thinking work better at their age compared to adulthood.
The reasons for such a significant change are pegged mostly on educational training and environmental factors that we will look at later that seem to affect brain structure and intellectual stimulation.
One thing is certain: IQ can change for the better or for the worse at different stages in a person's life.
Intelligence Types and Their Decline Rate
We now know that human intelligence experiences change throughout life. However, the age-related changes are not similar for both types of intelligence, and their differences significantly affect IQ.
To understand why different measures of intelligence and cognitive abilities decline at different rates, we need to get a bit of background on general intelligence.
General intelligence is subdivided into fluid intelligence, crystallized intelligence, and other abilities called working memory.
Fluid Intelligence
Fluid intelligence refers to problem-solving abilities that do not require previously acquired knowledge. Examples of fluid intelligence include:
- Quickly and efficiently solving novel problems
- Adapting to a new environment
- Processing and categorizing new information
Fluid intelligence is predominantly associated with brain regions like the prefrontal cortex and parietal lobes, which cover areas like executive function, visual processing, and coordinating movement and verbal abilities.
This type of intelligence helps young adults learn faster than older adults. It's solely responsible for your child or grandchild beating you on the gear cube or the newest game online!
Crystalized Intelligence
Crystallized intelligence is more connected to the hippocampus, a brain structure in the inner fold of the temporal lobe involved with learning and storing long-term memory.
An excellent example of crystallized intelligence is solving a math problem by recalling and using the correct formula. Crystallized intelligence is what we would call 'book smarts.'
If you encounter a new challenge at work and solve it by recalling a previous experience, you'll have utilized both types of intelligence.
Several studies have shown that age affects both types of intelligence differently. This means there are diverse intelligence peaks based on a person's age.
Brace yourself; you're in for a rollercoaster of research findings.
Research on Intelligence and Age
Previous research has shown that fluid intelligence peaks from early adolescence to early adulthood and declines steadily as the individual ages. Hence, the term highly intelligent is commonly used to define young adults.
A 2011 study found that the speed for processing information appears to peak around the age of 18 to 19 and then starts to decline. They also discovered that short-term memory peaks at age 25, plateaus, and then declines at age 35.
While it may not be part of the intelligence test areas, the researchers also found that the ability to gauge other people's emotional states peaked in middle age, from 40s to 50s.
Meanwhile, another study claims that inductive reasoning peaks in middle adulthood rather than in adolescence. So, while we can deduce that fluid intelligence abilities like processing speed and working memory peak mostly in adolescence, it would be incorrect to say so for all abilities in this subdomain of general intelligence.
People continue learning new things and gaining new experiences. For this reason, it has been established that crystallized intelligence increases with age. Cognitive skills relying on accumulated information or experiences peak later in life, from 60s to 70s.
These include language skills, vocabulary, and recalling general knowledge, like ostriches can't fly. Most experts attribute this improved or resilient cognitive function to extensive reading and a healthy lifestyle.
What Other Factors Can Cause IQ to Decrease?
We know fluid intelligence peaks and declines depending on the adult age range. But are other factors influencing intelligence decline and consequently leading to IQ decline?
The answer is Yes.
Here are some of the other factors that can cause IQ to change:
Head Injury
A head injury typically involves a direct hit to the head or sudden movements that jolt the brain back and forth against the skull, causing lesions, tears, bruising, and swelling of the brain. Such traumatic events can lead to a brief IQ decrease of about 1 to 2 points, but it is steadily gained over time.
The extent of IQ decline can vary depending on factors such as the severity and location of the injury, the individual's age and overall health, and the effectiveness of rehabilitation efforts.
However, studies have connected brain injury with the risk of premature aging, which leads to faster cognitive decline and long-term intellectual impairment.
Some of the most affected cognitive abilities include memory, attention, and problem-solving skills.
Alcohol and Substance Abuse
High alcohol consumption and substance abuse can alter how the brain works, leading to impairment of brain functions that support cognitive tasks. Chronic alcohol and drug use can also damage and disrupt neurotransmitter systems, further impacting cognitive abilities.
Some studies have found evidence that directly associates alcohol and drugs with decreased scores on IQ tests.
Poor Nutrition
'You're what you eat' has never meant more for your IQ score. Poor nutrition can lead to deficiencies in essential nutrients necessary for brain health, leading to a decline in IQ.
For instance, inadequate intake of nutrients such as omega-3 fatty acids, vitamins, and minerals can affect cognitive function and contribute to a decline in IQ over time.
On the other hand, a balanced diet rich in nutrients that support brain health, such as fruits, vegetables, whole grains, and lean protein, can help maintain cognitive abilities and potentially prevent declines in IQ.
If that doesn't surprise you, look at this.
A study published in the European Journal of Epidemiology found evidence connecting a poor diet — rich in fat, sugar, and processed food to decreased IQ in later childhood. In contrast, a healthy diet increased an IQ score by 1 to 2 points.
Want to Keep Your IQ at Its Best?
Aging is inevitable, and its effect on fluid intelligence is unstoppable. That said, there are things you can do to avoid the decline of your IQ, including:
1. Lack of Mental Stimulation
Mental stimulation can be classified as any activity that exercises the brain. Cognitive stimulation keeps the brain at peak condition, and the reverse is also true. Lack of stimulation can lead to cognitive decline in the form of poor memory, impaired attention span, and other problems.
What to do
Play Brain Games — playing games like chess and cards and solving puzzles improves problem-solving, memory, and critical thinking skills. It is one of the most recommended habits for people who develop dementia to slow cognitive function.
Read — 30 minutes of reading a book daily can do wonders for your memory and vocabulary. Even better, a reading routine boosts crystallized intelligence, which increases with age. But when it comes to accessing knowledge throughout life, you have to fill the cup to drink from it, which is an analogy.
Continue Learning — Be open to learning new ways of doing things. Asking a young painter a new way to create a painting or solve a math problem in educational activities can create what is known as a "cognitive reserve." This reserve helps the brain deal with potential neuropathology more efficiently, compensating for cognitive decline associated with aging or other factors.
2. Chronic Stress
We get it. We live in a fast-paced world now, and many things we do can bring stress into our lives. But what if we told you that prolonged stress levels could harm your cognitive abilities in your later years?
High stress levels have been shown to significantly affect cognitive functioning and the ability to maintain brain-building activities like playing games or reading.
What to Do
Meditation and Breathing Exercises — The University of Yale recommends learning and practicing mindfulness to improve IQ-connected areas like working memory, visual search, and executive functioning.
Seek Help — Seeking help from a supportive loved one or a mental health professional will allow you to find the best solutions to your problems and keep you on a path of positivity.
3. Lack of Physical Exercise
Lack of physical exercise leads to decreased brain neuron stimulation that controls your routine activities. It also predisposes you to serious conditions like Alzheimer's and heart disease.
What to Do
Exercise — Engage in 60 to 150 minutes of physical exercise every week to increase cardiovascular fitness and brain health. This will allow for continuous brain stimulation and help you score some extra IQ points.
For more information, read a more detailed guide on the best ways to improve your IQ score.
4. Over-Reliance on Technology
The impact of modern technology and the digital age on IQ is a topic of ongoing research and debate. Some claim that information overload, excessive screen time, multitasking, and over-reliance on technology may have a negative effect on cognitive abilities and that these factors are probably to blame for declining IQs in America.
Others argue that interaction with complex video games and problem-solving software can improve various cognitive functions, such as spatial awareness, strategic planning, and problem-solving skills. Technology provides opportunities for learning and mental development and is in no way harming our cognitive abilities.
What to do
Use Technology Mindfully — Use technology in a balanced and mindful manner. This is more like setting boundaries on what you can use technology for and what requires a good old-fashioned thought process and manual implementation.
That said if you're a millennial, Gen Z, or Alpha who can't keep a gadget down, incorporate activities that promote cognitive engagement and critical thinking into your daily routine to maintain cognitive health.
It’s a Lifetime Process
Human intelligence is complex. Many aspects of overall intelligence determine an individual's IQ score over their lifetime.
However, the extent and direction of these changes depend, to some extent, on various factors, including lack of mental stimulation, chronic stress, education, and over-reliance on technology.
Understanding that different facets of IQ can change with age underscores the importance of a stimulating environment and healthy lifestyle to help maintain and enhance cognitive functioning as we age.
While the studies support IQ changes for better or worse, no one can predict how life turns out, and individual differences are bound to create varied results.
Certainly, you can improve intelligence at any age and enjoy the benefits throughout your life.
Recommended Reading
Why Take an IQ Test? Use Your IQ Test Score for Self-Improvement
Surprising Myths and Realities about Intelligence Quotient: How Important Is IQ to Success?
