Does I.Q. Decline with Age?

   Though there is some evidence that the Intelligence Quotient (IQ) can increase during early childhood, it is supposed to remain relatively constant during adulthood. But the reason for this constancy is purely statistical and not biological.

   There are several different kinds of IQ tests and all of them are imperfect, but they are believed to provide a rough measure of a person’s reasoning ability. An IQ of 90-110 is considered average. After testing for verbal skills, visual-spatial abilities, mathematical reasoning and memory, a person’s raw score is calculated.

   This raw score is corrected for age, and then plotted on a bell curve against the scores of similarly aged people in the general population. In other words, IQ is not only a calculation, it is a comparison to other people of the same age. So, theoretically, a person of any age should always fall into the same percentile when compared with their peers.

   While one’s IQ may stay the same, most people do show a modest decline in mental performance on IQ testing as they age. Verbal skills seem to be retained the longest, but memory, mathematical ability and visual-spatial reasoning start to decline slowly around and 35, and more considerably after age 65. -Sean Kenniff, MD