Does age cause intellectual decline?

This is a question that has haunted mathematicians and physicists as well those in other high IQ professions. In 1927, physicist Paul Dirac, who won a Nobel Prize at age 31 for his work in quantum physics, wrote the following quatrain:

Age is, of course, a fever chill
That every physicist must fear.
He’s better dead than living still,
When once he’s past his thirtieth year.

Age is, of course, a fever chill, That every physicist must fear. He’s better dead than living still, When once he’s past his thirtieth year.

In the 1940’s Raymond B. Cattell proposed that human intelligence is composed of two parts: fluid intelligence (measured by IQ) plus crystallized intelligence (accumulated knowledge and experience). It has been discovered that our fluid intelligence reaches its maximum in early adulthood and then enters a gradual decline into senescence. However, the decline in fluid intelligence is slow and is more than compensated for by an increase in crystallized intelligence as we age, so our total intelligence (called g) reaches a peak somewhere in middle age, depending on the skills measured.

The following excerpt from Intelligence, IQ & Perception (chapter 5) shows the ages at which those working in the natural sciences do their best work.

… in 1991, Simonton published a comprehensive study of 1825 scientists and inventors in which he used a variety of criteria to assess the ages at which the cognitive elite in a variet ,y of fields produced their first, best, and last creative work. Though assigning a precise time to the “best work” is somewhat subjective and therefore approximate, the trends have been identified by averaging these data for a significant number of individuals in each discipline. Table 5-3 presents the mean ages at which scientists in various domains of the natural sciences reached these three milestones in their careers.

Table 5-3 reveals that on average, a scientist’s creative productivity begins near age 30, attains a peak around the 40th year, and gradually comes to a close shortly after age 50. Furthermore, the mean age at which mathematicians do their best work is 38.8 years, with a standard deviation of 10.7 years. Assuming that these ages are normally distributed, we can conclude that about 45% of mathematicians do their best work at or slightly beyond 40 years of age. Similarly, almost half of the physicists and chemists achieve peak performance soon after age 40. Therefore, the belief that all researchers in science and technology are doomed to mediocrity after age 40 is not supported by the data. As Simonton observes, “many of these notions [from biographies and historical chronologies] in fact take the explicit form of ‘myths,’ such as the recurrent statement that physicists are ‘over the hill’ at age 30.”

We observe similar patterns in achievement in the arts, the social sciences, and chess, although the ages at which the best works are created varies across disciplines. The causes of the decline in fluid intelligence are attributed to a decrease in neural efficiency, though the physiological causes of this decrease are not well understood. Based on informal personal observation over the past few decades, I would suggest that those who engage regularly in high level intellectual tasks, suffer a slower decline in mental acuity than others, though I have no research data to support my conjecture.

10 thoughts on “Does age cause intellectual decline?”

    1. Thank you for your comment, Mike. We included chess in our analysis because it involves a lot of the cognitive skills we bring to bear in academic pursuits. We found that over the past three decades the median age at which each chess master first became a World Champion was 30.5 years and that performance in chess peaks, on average, before 40 years of age.

  1. Leonardo Córdova

    Very well written blog! Statistics may be sometimes (a bit) ambiguous, but these ones are always based on concrete facts, so we can have a notion of very complicated topics like psicology and psichometrics by this way(especially with persons with this generally huge level of intelligence and reasoning capacity). Interesting and pleasing to read, thanks for making this.

      1. My hat’s off to you Joseph. Your desire to learn will be your salvation! The brain has remarkable plasticity and if you challenge it, you will regain many functions. Keep reading, writing and thinking and you’ll be pleased with the results.

  2. Thank you for the info! As an older adult (57) I have been thinking of ways to challenge myself , I do play Chess daily with an easy to use App however I find my biggest and most rewarding challenge was learning to trade financial derivatives specifically option contracts as a second ‘business’. In High School I tested 95 plus percentile in Math and Sciences, and have worked as a Technician my whole career. although it has been rewarding its not particularly taxing. I am a bit amazed at the ability the brain has to learn new things even as we age!
    I also enjoy teaching younger techs that I work with although not required of my job I find it rewarding to pass on some of my ‘general intelligence”

    1. Robert, you obviously have an active mind and you’ve continued to challenge it. If you keep doing what you’re doing, the odds are in favour of your carrying your high intellect into your 80’s and 90’s. I hope you remain on the planet for many years, because highly intelligent people are scarce and we need to retain as many as we can! Wishing you well, Brendan

  3. Thank you for this, I was a dumber during the early primary days at the age of 7-12 I hardly think of an answer when a question is asked but at the age of 13-20 my thoughts started to become clear and I began to answer some of the question on other subjects not mathematics that makes me to take up social science courses, I was not interested in taking up science courses. I try to be creative in doing design and other work but couldn’t I was forcing myself all I did was copying others work but I keep practicing drawing that is at the age of 21-26 little bit of creativity and at the age 27 now I can see a clear picture of things in my mind that’s makes me to be creative and a desire for creating new things began in me, also I find very interesting in studying science and do things on my own..

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