Actually, we can improve IQ through our formative years, and the earlier the better. However, once we reach adulthood, we cannot increase our 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.
It is during our early formative years 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. By the time we enter puberty, a major portion of the neural connectivity is slowing, but it is still possible to increase our IQ through intellectual stimulation. Recent research involving a group of secondary school students showed that some students showed an increase of as much as one standard deviation in IQ (15 points) over a period of 3 years through increased learning activities. (See: Do any studies exist on whether people can become more intelligent by practicing activities that require intelligence? – Intelligence and IQ ) However, most students showed only modest increases in IQ. 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.
The “take home message” is that we continue to evolve mentally and physically throughout our lifetime. The best time for us to bring about large changes occurs during our formative years. However, 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 shows 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.
