Ageing and Cognitive Decline

This doesn’t have a lot to do with philosophy, but it’s a curious thing, so what the hell, I thought.

I’ve been having a mid-life crisis for about the last fifteen years. Obviously, chasing girls, oops, sorry, women, is a large part of the story, but I’ve also become pretty interested in the link between ageing and physical decline.

Anyway, I’ve just noticed that a new piece of research has been published in the BMJ, which shows that cognitive decline is already evident by the time people hit middle age. Basically, they looked at tests of memory, reasoning, vocabulary, etc., and found that

all cognitive scores, except vocabulary, declined in all five age categories (age 45-49, 50-54, 55-59, 60-64, and 65-70 at baseline), with evidence of faster decline in older people.

So that’s pretty depressing, but perhaps not all that surprising. I remember Norman Levitt once telling me something to that effect about the career path of mathematicians:

You do slow down. Not everybody, but there is a tendency to be really bright when you’re twenty-two, and then it becomes more of a slog as you get older. People’s really brilliant stuff tends to happen when they’re younger. There are exceptions, but you can look at people’s career paths and you find that whilst they might be brilliant at twenty-four this eases off as they get older. It comes with the territory.

But here’s the thing, and perhaps somebody who knows this field, might be able to shed some light on this matter. If you’re doing that sort of longitudinal study, how do you control for motivation? If I had ever taken an IQ test in my 20s, or perhaps even my 30s, I’d have been pretty keen to do well. But now, well I wouldn’t give a bugger. Even if I told myself I had to perform to the best of my ability, I’m pretty sure it’d be futile, because I just don’t care enough. Possibly I’m unusual in this respect, but I doubt it, and certainly it’s an open possibility that motivation will decline with age (which might have a physiological component, of course, but which might not generalize – in other words, it’s possible that if one was doing some task that one considered important, then motivation levels would stay high, with concomitant improvements in concentration, and thereby performance).

So that’s my question. How do you control for motivation in these sorts of longitudinal studies?

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23 Comments.

  1. By making the participants believe that they will live forever?

  2. Or one has to offer a hefty financial motivation per IQ point.

  3. ‘Penn Research Demonstrates Motivation Plays a Critical Role in Determining IQ Test Scores’

    http://www.upenn.edu/pennnews/news/penn-research-demonstrates-motivation-plays-critical-role-determining-iq-test-scores

    Duckworth, A. L., Quinn, P. D., Lynam, D. R., Loeber, R., & Stouthamer-Loeber, M. (2011). Role of test motivation in intelligence testing.

    http://www.sas.upenn.edu/~duckwort/images/Role%20of%20test%20motivation%20in%20intelligence%20testing.full.pdf

  4. s. wallerstein (amos)

    I don’t know anything about testing, but I’m 65 and there has been some cognitive decline, which I rationalize by an attitude of sour grapes, generally related to motivation.

    No, I’m not going to study formal logic (which I could have learnt easily at age 20, I tell myself), but I have nothing to prove anymore.

    No, I’m not going to argue with that person online, but I’m no longer on a macho competitive trip.

    No, I’m not going to play chess, but I’ve transcended the need to win.

    No, I will not argue for the sake of arguing, but that’s because I’ve developed my feminine side.

    And so on….

  5. Ha! but, the >45 years are better at many things than the <45 years. And they are, on avearge, wealthy (money & wisdom) as a group and broadly more at peace with themslves.

    I wonder if you could relate the research to the "maturity curve". And give a more balance view. Sure, the purpose of the research is important (I have not read the article) – and it could be to find out, say, the on-set of certain mental illnesses (prognose and intervene, before it gets worse etc).

    But to your point, motivation, will undoubtedly, play a part – as always where girls, sorry, women are concerned, no matter how old you are as a boy or man (-that, I guess, applies to most of us males)

  6. @Jim – Ah, thanks. I think possibly I knew about that study. But… if it’s right, then you’ve got to control for motivation.

    @Amos – I tell myself the same thing about chess. Thing is, though, I’m not sure it’s just a rationalization. I was extremely keen on chess up until the age of 10 (as in, I won competitions, keen). And I did have a burning desire to win at that age. But I lost that, and that was that, pretty much (I lost it for chess because I became obsessed with soccer).

    @POD – I did actually think about motivation and girls, sorry, women. I was hopeless at high school until the age of 16 (mainly because I spent almost literally every moment of my spare time playing either soccer or tennis). But the funny thing was, aged 16, I got it into my head, that I’d have more chance of attracting girls, sorry, women, if I excelled academically. Yeah, I know, god knows what I was thinking, and it certainly didn’t work, but it did transform my academic performance.

    I’d say motivation was extremely important in all this stuff.

  7. @Jeremy – well keep in mind that Professor Hawking, the distinguished cosmologist, said yesterday that, the thing that most preoccupied his mind, was Women – and that “They are a complete mystrey” -Yet he knows a thing or two about the Universe formation and blaok holes.

  8. Jeremy Stangroom

    @POD – Yes, I noticed that the “complete mystery” bit didn’t go down too well in certain parts of the blogosphere…*

    *And, admittedly, it did make him seem a little daft…

  9. s. wallerstein (amos)

    The thing about women is that they are much less standarized, much less like one another, than are men, so any theory of what women are like is not going to help you understand any given woman.

  10. I’m sure you’re wrong about this, Jeremy, but I can’t be bothered to work out why.

  11. If you want to feel more depressed, look at the graph in http://www.gwern.net/DNB%20FAQ#aging

    > But here’s the thing, and perhaps somebody who knows this field, might be able to shed some light on this matter. If you’re doing that sort of longitudinal study, how do you control for motivation? If I had ever taken an IQ test in my 20s, or perhaps even my 30s, I’d have been pretty keen to do well. But now, well I wouldn’t give a bugger. Even if I told myself I had to perform to the best of my ability, I’m pretty sure it’d be futile, because I just don’t care enough. Possibly I’m unusual in this respect, but I doubt it, and certainly it’s an open possibility that motivation will decline with age (which might have a physiological component, of course, but which might not generalize – in other words, it’s possible that if one was doing some task that one considered important, then motivation levels would stay high, with concomitant improvements in concentration, and thereby performance).

    I would first ask, why we would want to take any account of motivation?

    Yes, if we define one’s ‘true’ IQ or mental ability as one’s top performance under the optimum condition, whatever that is – perhaps a gun at one’s temple? ‘Solve this matrix problem *or else*!’ – and then expect our IQ tests to not be confounded by motivation and predict as accurately as possible our peak performance under the optimum condition, then declining motivation with age is a concern.

    But usually we are interested in IQ because it doesn’t predict performance in just a extremely narrow range of conditions (a gun at one’s temple, the 3 hours one is in the SAT test center) but performance over a broad range of conditions, and indeed, performance over one’s entire life.

    That’s why it was called ‘g’, for the ‘general’ factor that showed up.

    So if older people score lower than they ‘could’, why is this not as it should be? If they are not so motivated on IQ tests, well, they probably are not so motivated on everything else too.

    (Why? Maybe they’re bored, or health bothers them, or experience has taught them the futility of trying, etc. But IQ isn’t about explaining *why*, it’s just about describing and predicting.)

  12. So if older people score lower than they ‘could’, why is this not as it should be? If they are not so motivated on IQ tests, well, they probably are not so motivated on everything else too.

    Right, which I suspect – for no good reason! – might well be the case.

    But the crucial thing is that it doesn’t preclude “optimum” performance where motivation levels are high. This is important because we want to think that if we’re really engaged in something, passionate about it, then we’re still going to be able to do it as well as we used to be able to do it (or at least, that our decline isn’t too dramatic).

    The other reason it’s significant is that it might well have implications in terms of the physiology of decline. For example, if it is related to arousal levels, or competitiveness, or something, then it’s possible this sort of research doesn’t tell us much about early onset Alzheimer’s, for example.

  13. s. wallerstein (amos)

    At my age, 65, motivation to perform well is as high or even higher than it was at age 20 (I’m more concentrated, less blasé), but (and this is big “but”) I’m only motivated by tasks in which I know that I can perform well and unlike at age 20, I avoid taking risks in selecting intellectual tasks.

    I have become very specialized and my specialization is centered in areas where I know that I perform well.

    Perhaps one could say that I know myself better and now know where to center my efforts, but one could also say that I avoid tasks which might diminish my self-esteem and that I took more risks regarding my self-esteem at age 20.

  14. “So that’s my question. How do you control for motivation in these sorts of longitudinal studies?”

    Take a measure of motivation and see if it is correlated to performance? I mean that quite seriously.

    I can’t access the study, even the Abstract, so I can’t read what they actually did but I would be interested to know (a) the rate of decline, and (b) how they controlled for a range of other potentially confounding factors (e.g. health related factors which could interfere with both motivation and performance).

  15. I will add that early studies of IQ which showed large declines in IQ with age were flawed by being cross sectional and not adequately controlling for confounding factors. Later studies showed (if my memory is correct, and it is suffering from age-related performance issues) a much more modest decrease.

  16. Take a measure of motivation and see if it is correlated to performance?

    Yeah, sure, though it wouldn’t be particularly easy. But what I meant was given that there is this data that already exists, how do you control for motivation when analysing it (given the possibility that motivation is a confounding variable).

    Odd that you can’t access it. I get the whole thing. (Maybe they restrict UK access or something).

  17. “But what I meant was given that there is this data that already exists, how do you control for motivation when analysing it (given the possibility that motivation is a confounding variable).”

    Without a measurement of motivation, or something known to be strongly correlated to it, I don’t see how it could be controlled for. (And I say that as someone with some expertise in multiple regression and related methods.)

    The research Jim cited (thanks Jim; interesting) showed that motivation could alter IQ by between about 1/3 and 1 SD — which is about 5 to 15 points — which could account for much of the age related decline.

  18. @Keith

    Right, that’s what I suspected. I guess one could look at what we already know about the effects of ageing on motivation (assuming we do know stuff), and motivation on IQ score, and then control on that basis, but it’d be highly unsatisfactory.

    which could account for much of the age related decline.

    Assuming, of course, that age does affect motivation…

  19. On the contrary ; as one gets older ; as it has happened in my case; we need to keep up with young competitors; within family in order to participate more fully in discussion ;making one self indispensable… lost a key i will find them TV Repair calling plumbers ,,supervision and such other mundane matters ..
    One can in fact improve the IQ score !!

  20. a relative passed away recently formerly an Army Man ” when he wished to go he stopped eating but asked for the remote to watch the Cricket match ;; then pulled out the mask tubes .

    Many aged persons do have motivation .. see a great grand child ; all this from India ;

  21. From someone else who just turned 50, while certain categories of cognition may decline as we age, other studies indicate that intelligence, as a complex process, deepens as we head towards or 70’s. What traditionally is called wisdom, begins to heighten and increase in middle age. Maybe the lack of motivation to do well on an ego-boosting I.Q. test is the beginning of wisdom?

  22. “Dave, my mind is going, I can feel it…”

    Certainly I’m well aware of my own cognitive decline.

    On the long-term, I’m rather grateful for the fact that my brain is generally slower and less busy than it once was. I used to have a great many more thoughts than I could really cope with.

    But certainly there is more recent and marked decline. I ebb and flow but the general downward direction seems quite apparent even in my contributions to the site over the last year. My memory is dimmer and I’m just not fit to do the reading and clear thinking that I was even a year ago. There are technical arguments I could have followed not so long ago and I no longer can. And this can be frustrating. I do seem to have the ability to write and think clearly at times. Sometimes I think I can still usefully ‘nail’ an idea. This seems to work best when what I’m motivated to do is try to help somebody else to understand something.

    When I engage in argument though –especially if it comes with less noble intent or is moved by anger – increasingly I slip into verbosity, confusion and indeed grumpy stupidity (my pomposity has got worse too). But I shouldn’t mourn the loss of cleverness, just regret the fact that I speak when often I shouldn’t.

    I’ve no wish to be as ‘clever’ as I once was. I would like to be wiser though. I don’t see any progress in my own case but I do see it in older people, those that can keep an open mind and resist the urge to cling to certitude. Wisdom seems only indirectly related to ‘intelligence’ and ‘factual knowledge’ and cleverness is wildly over-rated. Presumably the wise would have no interest in having their wisdom quotient measured even if such a thing could be done.

    There’s great truth in the old chestnut about Socrates and the oracle at Delphi, and knowing how much you don’t know seems to come (if it comes) with age.

  23. s. wallerstein (amos)

    Jim:

    You do have a remarkable ability to explain things, to help others to understand something, which entails capturing more or less what others probably know and what they do not know about a given a topic.

    Not all philosophers share that ability or on a less charitable interpretation of their behavior, many try to silence those of us without technical abilities in the field with a barrage of jargon and shop-talk, which often leaves me wondering if the philosopher is really saying anything or simply trying to win the argument by his or her mastery of jargon, much like a little child caught in a lie, who
    seeks to tire adults with an unending stream of meaningless, but high-sounding apologetics, without reflecting that he or she convinces no one, although he or she exhausts everyone.

    I often suspect that many philosophical arguments are “won”, because the winner is able to tire the other.

    A further, sad reflection: that one wins because he or she tires the other suggests that not much is really at stake in many philosophical debates.

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