Verbal and non-verbal intelligence changes in the teenage brain

24 Oct

A recent Letter in the Journal Nature takes on the question of how stable is intelligence in teenagers. The title is pretty self explanatory: Verbal and non-verbal intelligence changes in the teenage brain.

Consider teenagers. Is their IQ “set in stone”? By the time a kid is, say, 13, isn’t his/her intelligence pretty well demonstrated? What if you heard that IQ changes can change, up or down, by as much as 20 points during the teenage years? Would you be surprised? I was.

The article attracted my attention on its own merits, but also given the nature of the discussion that forms around early intervention and autism. Statements about “windows of opportunity” and times when the brain is “plastic” are common in discussions of autism focused educational therapies. For example, a study entitled “Early intervention and brain plasticity in autism” or “Autism: a “critical period” disorder?“. Certainly early childhood is a period of great learning and growth, but does the “window” of plasticity “close”?

Here is the abstract:

Intelligence quotient (IQ) is a standardized measure of human intellectual capacity that takes into account a wide range of cognitive skills1. IQ is generally considered to be stable across the lifespan, with scores at one time point used to predict educational achievement and employment prospects in later years1. Neuroimaging allows us to test whether unexpected longitudinal fluctuations in measured IQ are related to brain development. Here we show that verbal and non-verbal IQ can rise or fall in the teenage years, with these changes in performance validated by their close correlation with changes in local brain structure. A combination of structural and functional imaging showed that verbal IQ changed with grey matter in a region that was activated by speech, whereas non-verbal IQ changed with grey matter in a region that was activated by finger movements. By using longitudinal assessments of the same individuals, we obviated the many sources of variation in brain structure that confound cross-sectional studies. This allowed us to dissociate neural markers for the two types of IQ and to show that general verbal and non-verbal abilities are closely linked to the sensorimotor skills involved in learning. More generally, our results emphasize the possibility that an individual’s intellectual capacity relative to their peers can decrease or increase in the teenage years. This would be encouraging to those whose intellectual potential may improve, and would be a warning that early achievers may not maintain their potential.

” More generally, our results emphasize the possibility that an individual’s intellectual capacity relative to their peers can decrease or increase in the teenage years.” Those are quite powerful words.

The authors tested 33 subjects at two time periods:

They were first tested in 2004 (‘time 1’) when they were 12–16?yr old (mean, 14.1?yr). Testing was repeated in 2007/2008 (‘time 2’) when the same individuals were 15–20?yr old (mean, 17.7?yr).

And they found that the while the IQ scores were relatively stable, on average, individuals showed large changes:

The wide range of abilities in our sample was confirmed as follows: FSIQ ranged from 77 to 135 at time 1 and from 87 to 143 at time 2, with averages of 112 and 113 at times 1 and 2, respectively, and a tight correlation across testing points (r = 0.79; P<0.001). Our interest was in the considerable variation observed between testing points at the individual level, which ranged from -20 to +23 for VIQ, -18 to +17 for PIQ and -18 to +21 for FSIQ.

Individuals had changes in verbal IQ of -20 to +23 points, with large changes seen in performance IQ (PIQ) and full-scale IQ (FSIQ) as well. Twenty point swings in IQ, up or down? That’s a lot. As noted before, the study is rather small (33 subjects), but what makes this an impressive study is that they have physical data–brain structure data–to correlate with the changes in IQ. The authors performed MRI scans on the subject. These are shown in a Figure from the paper (click to enlarge):

The authors found that grey matter changed in specific areas of the brain and that these changes correlated with the changes in VIQ and PIQ.

The brain is not just “plastic” in terms of IQ scores, it is still able to physically change during teenage years.

Our findings demonstrate considerable effects of brain plasticity in our sample during the teenage years, over and above normal development.

If an early intervention program were to claim that some kids gained 20 IQ points, it would be huge. (Of course, if they had to admit that some kids lost 20 IQ points, it would also be huge, but in a different way)

But if non-autistic kids can see such large swings in IQ during the teenage years, why not autistic kids? Why not kids with intellectual disability and autism? Just as important as the potential for swings up in IQ are the losses in IQ. What if a kid ends up in a placement that is inappropriate to the level that IQ is lost?

I would love to see a study such as this one on autistic kids, especially those with intellectual disabilities, to track IQ and brain structure during age ranges outside of early childhood.

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9 Responses to “Verbal and non-verbal intelligence changes in the teenage brain”

  1. farmwifetwo October 24, 2011 at 14:12 #

    If our brains aren’t plastic then if we have a stroke or other illness/accident maybe they should just build our coffins and bury us…. eye-roll.

    The biggest lie out there is this “window of opportunity”. Had it been true the eldest would not have become fluent by age 8 and reached normal “intelligence” at age 11. The youngest would not be adding more words daily to his verbal volcabulary and we should just toss that flipbook we just got into the garbage.

    We learn, we are always learning. Problem is, most people once they get past those early years stop pushing. It has little to do with intelligence and everything to do with opportunity.

  2. stanley seigler October 24, 2011 at 16:58 #

    [farmwifetwo] The biggest lie out there is this “window of opportunity”. Had it been true the eldest would not have become fluent by age 8 and reached normal “intelligence” at age 11.

    and there was a 2005 story of a non-verbal who began talking at 50
    http://us.mg6.mail.yahoo.com/neo/launch?.rand=asr5vjs8gvu7g

    [LBRB say] By the time a kid is, say, 13, isn’t his/her intelligence pretty well demonstrated? What if you heard that IQ changes can change, up or down, by as much as 20 points during the teenage years? Would you be surprised? I was.

    COMMENT
    i’m not…so little we know re autism intelligent (AI)…and relatively so little research by the publish or perish crew re AI

    this link (cbs60 min preview…cant find the complete program)

    http://www.cbs.com/primetime/60_minutes/video/?pid=eoN7558OKLUPIBYc0LGyeD3Q8OEkiNP6&vs=homepage&play=true

    …provides another clue (w/ ipad) to AI…as did the mid 1960s “talking typewriter”…there was no follow up on the unbelievable communications on the talking typewriter.

    stanley seigler

  3. stanley seigler October 24, 2011 at 18:11 #

    CORRECTTION

    and there was a 2005 story of a non-verbal who began talking at 50
    http://us.mg6.mail.yahoo.com/n…..5vjs8gvu7g [INCORRECT LINK]

    CORRECT LINK: http://www.autismconnects.com/publisher/articleview/frmArticleID/270/

    stanley seigler

  4. stanley seigler October 25, 2011 at 20:00 #

    re: this link (cbs60 min preview…cant find the complete program)

    http://www.cbs.com/primetime/6…..;play=true

    the complete 60 min segment (APPS for Autism) now on line:

    http://www.cbsnews.com/video/watch/?id=7385686n&tag=pop;videos

    this what was possible in the mid sixties with the talking typewriter.

    stanley seigler

  5. stanley seigler October 25, 2011 at 21:36 #

    LBRB,

    re: “stanley seigler Your comment is awaiting moderation.
    October 24th, 2011 16:58:51”

    is there a problem…

    stanley seigler

  6. stanley seigler October 26, 2011 at 02:29 #

    LBRB,

    why is ” stanley seigler October 24th, 2011 16:58:51” still on moderation…

    stanley seigler

  7. stanley seigler October 26, 2011 at 18:18 #

    @ sullivan

    no longer being moderated…thanks for checking…

    stanley seigler

  8. James Dane October 30, 2011 at 05:52 #

    IQ Review reviewed a great IQ Increasing product, I’ve been very happy with my purchase and the review was very accurate. Feels like the autism fog has cleared up.

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