In response to “An Old Infirmity” (Vol. 3, No. 2).
To the editors:
“No other animal passes so large a portion of its existence in a state of absolute helplessness, or falls in old age into such protracted and lamentable imbecility.”
Humans, perhaps uniquely among the creatures on this planet, can travel mentally in time and imagine their remote future lives.2 The prospect of suffering the “lamentable imbecility” of old age that John Herschel noted is a particularly unwelcome prospect, and therefore acts as a powerful driver for a vast industry promoting potions, programs, and pointers aimed at halting or slowing age-related decline.
Some evidence suggests that the attitudes people hold about their own aging may influence the trajectory of future losses of cognitive function, pointing to new potential avenues for protecting future well-being.3 Could some kind of public awareness campaign or psychotherapy push us to adopt better attitudes that will in turn increase our chances of happiness and well-being in old age? This is an appealing (and for some a potentially lucrative) vision.
As von Hippel compelling demonstrates, we need to be cautious not to mistake correlation for causation. There are alternative explanations. People with positive attitudes about aging may simply be the ones who indeed have reason to be positive because their relatives lived long, healthy lives and their own underlying health is robust. In that case, changing someone’s attitudes may bring about unrealistic expectations, rather than any desired effects on age-related change.
Decline is as inevitable as death. Many of us think of life as comprising essentially three main stages: growing up, the normal adult life with full command of our powers, and the dreaded decline in old age. In reality, we are constantly changing. Our categorical labels hide a much more dynamic ongoing process.
Diverse capacities peak at different times. Consider elite sports people. A professional football player may be at his best between the ages of twenty-five and thirty. This is a rather short period given how many years of committed training brought about improvement, and how many more years he may play with gradually decreasing capacities. He would be well advised to try to enjoy the journey, as the top performance level may be disappointingly fleeting. There are, of course, large individual differences in the peak performance and the speed of decline. What should be clear, though, is that capacities do not remain unchanged.
As it is with athleticism and muscles, so it is with our minds and brains. Our brains grow gradually with age, reaching their full size before puberty. Throughout adolescence, cortical white matter increases and grey matter becomes thinner, reflecting ongoing pruning of synapses and the myelinization of axons. This late maturation is evident even in the most basic aspects of cognition. Performance on the simplest executive control tasks improves throughout adolescence.4
It may come as a surprise to learn that certain aspects of brain development are not complete until much later still. The uncinate fasciculus, a white-matter tract linking the orbitofrontal cortex, amygdala, and temporal regions that is implicated in socio-emotional processing, only reaches full maturity during the mid-thirties.5 It then declines. Change is constant.
In cognitive capacities, as in athletic capacities, many of us would like to buffer the deterioration and are willing to expand considerable time and money combating the rot. Researchers too, as von Hippel notes, may also be willing to invest considerable effort. And they may be disinclined to accept evidence suggesting that certain decline cannot be ameliorated.
When we learn, for instance, that being bilingual may protect against decline and delay the onset of dementia, we take note.6 We may subsequently promote the learning of a second language, be more inclined to look for evidence supporting the power of such learning, and would be reluctant to accept anything to suggest otherwise, particularly when we have already made a big effort. The latest meta-analysis of prospective studies, it should be noted, sadly does not support the effect.7
This may reflect our tendency to engage in self-deception—a topic that von Hippel has long researched.8 Self-deception produces a biased view of the world, and so as scientists we ought to safeguard against it. Von Hippel’s skeptical analysis is a welcome antidote to premature enthusiastic endorsements.
From an individual’s perspective, some systematic bias may be a healthy strategy. It may even have evolved because it benefits us. Our tendency to exaggerate the emotional impact of future events may be important in driving us to avoid future harm and secure future rewards today.9 Being realistic may not always be as useful and desirable as it sounds. It turns out that mildly depressed people tend to be quite accurate in their predictions compared to the rest of us, who mostly tend to demonstrate an optimism bias.10 A bias that may, in fact, be very useful. “Optimism,” Noam Chomsky is said to have remarked, “is a strategy for making a better future. Because unless you believe that the future can be better, you are unlikely to step up and take responsibility for making it so.”
And remember that growing old is not so bad when you consider the alternative.
Thomas Suddendorf is Professor of Psychology at the University of Queensland, Australia.
- John Herschel, A Preliminary Discourse on the Study of Natural Philosophy (London: Longman, 1830). ↩
- Thomas Suddendorf and Mmichael Corballis, “The Evolution of Foresight: What is Mental Time Travel, and is it Unique to Humans?” Behavioral and Brain Sciences 30 (2007): 299–313, 45–51. ↩
- Becca Levy et al., “Longevity Increased by Positive Self-perceptions of Aging,” Journal of Personality and Social Psychology 83 (2002): 261–70. ↩
- Beatriz Luna et al., “Maturation of Cognitive Processes from Late Childhood to Adulthood,” Child Development 75 (2004): 1,357–72. ↩
- See Miya Asato et al., “White Matter Development in Adolescence: A DTI Study,” Cerebral Cortex 20 (2010): 2,122–31; Catherine Lebel et al., “Diffusion Tensor Imaging of White Matter Tract Evolution Over the Lifespan,” Neuroimage 60 (2012): 340–52. ↩
- Jared Diamond, “The Benefits of Multilingualism,” Science 330, no. 6,002 (2010): 332–33. ↩
- Naaheed Mukadam, Andrew Sommerlad, and Gill Armstrong, “The Relationship of Bilingualism Compared to Monolingualism to the Risk of Cognitive Decline or Dementia: A Systematic Review and Meta-Analysis,” Journal of Alzheimer’s Disease 58 (2017): 45–54. ↩
- William von Hippel and Robert Trivers, “The Evolution and Psychology of Self-deception,” Behavioral and Brain Sciences 34 (2011): 1–56. ↩
- See Timothy Wilson and Daniel Gilbert, “Affective Forecasting: Knowing What to Want,” Current Directions in Psychological Science 14 (2005): 131–34; Beyon Miloyan and Thomas Suddendorf, “Feelings of the Future,” Trends in Cognitive Sciences 19 (2015): 196–200. ↩
- Tali Sharot, “The Optimism Bias,” Current Biology 21 (2011): R941–R5. ↩