• Question: How much would you expect your IQ to drop over 60 years?

    Asked by 7krakatoa7 to Alex, Amy, Andy, Georgia, Ollie on 16 Jun 2011. This question was also asked by robsterwrecker.
    • Photo: Amy Reeve

      Amy Reeve answered on 16 Jun 2011:

      This is a really good question! I don’t think you’re IQ will change as you age. People with diseases like Alzheimer’s disease will still have the same IQ, what changes is their ability to remember and recall things.

      The best thing to do as you age is to keep your brain active, this can be by doing anything from a crossword to reading books. 🙂

    • Photo: Andy MacLeod

      Andy MacLeod answered on 16 Jun 2011:

      Hi 7krakatoa7. You’d expect IQ to decline a little bit over time, but childhood IQ is still a pretty good indicator of intelligence in later life.

      To go into a bit more detail on Amy’s answer, there are lots of different areas of intelligence, and lots of different tests we can use to measure them. All of these tests are correlated to some degree, so if you do well on one, you’re likely to do well on the other. “IQ” is just one of these tests.

      Each test (like verbal reasoning, memory or reaction time) has unique factors that make some people better at them than others. But there is also a common factor, called “general intelligence”, that will make some people do better than others at ALL of the tests. We can use statistical techniques to seperate out this general factor for each person, and it’s that I’m talking about when I say we “measure intelligence”.

      We can brodaly classify intelligence into two major types of areas that we call “fluid” and “crystallized”. Fluid is more to do with abstract reasoning and puzzle solving. Crystallized intelligence involves the application of acquired knowledge – for example in a vocabulary test (one of the tests we do is to see how many words beginning with a certain letter people can name in a minute)

      These two types of intelligence both change as you get older, but the way they change is slightly different – fluid intelligence generally tends to decline with age more rapidly that crystallized. But even so, your thinking ability in childhood is a pretty good indicator of how you’ll think in old age. I work a lot with data from the Lothian Birth Cohorts – children in Scotland who were given intelligence tests at age 11, who my colleagues have tracked down and given them similar tests in old age – up to 70 and beyond. They’ve found that for what’s called “normal cognitive ageing” – that’s people who fall within the normal intelligence range, and haven’t got dementia or other cognitive disorders, that while there is some decline in mental abilities over people’s lifetime, mostly their childhood IQ is related pretty closely to their IQ in old age.