Each of us is born with a unique intellectual potential that is determined by the genes we inherit. Achieving that potential requires an environment that offers optimal stimulation. The greatest opportunity to improve our IQ occurs in our formative years, and the earlier the better. It is during these early formative years (between birth and age 5) that our brains produce neural connections (synapses) at a prodigious rate, pruning the connections that are not used and building strong networks around those that are stimulated by the environment. Part of this stimulation comes from parental care and nurturing, that involves touching, feeling and communicating with language. Play is highly stimulating as are physical activities involving walking, running, climbing and balancing. Tactile experiences such as, playing a musical instrument, building with blocks and solving puzzles, are a vital component of intellectual development. Reading stories and discussing relationships between the characters in these stories helps young children make sense of social situations and stimulates their imagination. Many of those who have become the highest achievers as adults, have come from homes with a high degree of intellectual stimulation, where conversations at an adult level were shared with children.
Around the time we enter puberty, there is another proliferation of neural connectivity and pruning, that offers us an opportunity to increase our IQ toward its maximum potential. Recent research involving a group of secondary school students showed that some students exposed to special learning experiences showed an increase of as much as one standard deviation in IQ (15 points) over a period of 3 years, although most students showed only modest increases in IQ (See: Ramsden, Sue. et al. 2011. “Verbal and non-verbal intelligence changes in the teenage brain.” Nature. Vol. 479. pp. 113-116.) . The significant increases in IQ were also evident in changes in brain structure evident in MRI scans. The study involved a small sample and would require replication on a much larger group to become a general finding. However, it suggests that the teenage years offer important opportunities to stimulate interests that foster the capacity to think in the abstract and master some of the deepest concepts in subjects like mathematics and physics.
However, once we reach adulthood, we cannot increase significantly our brain’s neural efficiency, known as “fluid intelligence”, because the major period of growth in our neural circuitry is behind us. However, while our fluid intelligence begins to decline, we can continue to increase what is called our “crystallized intelligence,” through the acquisition of knowledge. That’s why our greatest intellectual achievements tend to occur between our late 20’s through our early 40’s.
The graph below shows that our fluid intelligence begins to decline in early adulthood as our crystallized intelligence increases. However the combined effect of both components of intelligence begins to decline as we move through middle age.
This explains why mathematicians and physicists tend to reach their intellectual peak shortly after age 30, while lawyers and doctors reach their intellectual peak much later when acquired knowledge and wisdom play a greater role.
The “take home message” is that we continue to evolve mentally and physically throughout our lifetime. Furthermore, the best time for us to bring about large changes in our intelligence occurs during our formative years. Throughout adulthood, we can increase our abilities and delay our ultimate decline. The many biographies of high achievers that I have researched over the years reveal that those who are mentally active tend to retain a high level of mental acuity into their late senior years. The adage “use it or lose it” that applies to physical abilities seems also to apply to intellectual abilities.
