I used to be interested in the effect of aging on cognition in an objective sense, but now, at age 84, the issue becomes very close at hand. I frequently challenge my memory to be sure that I'm not losing it. I too often forget where my car is in the parking lot. Is this an omen? The current issue of Science magazine, our premier journal, contains an entire section entitled "The aging brain." (1)
In the articles the overall thrust is laid out, "One thing we already know is that our mental lives benefit when we lead lives that are not only physically healthy but also intellectually challenging and socially engaged." The article brags about the brain's outstanding flexibility, that it adjusts wonderfully to constructive as well as destructive challenge.
This field has been of major interest to me for a number of years. One of my fundamental references is the Nun Study of 1986. (2) In it, Snowden retrieved the archival autobiographical essays written when a group of prospective nuns were 22 years of age, and anticipating their service. Subsequently a retrospective analysis of these essays found that the linguistic complexity of the original essays correlated strongly with the cognitive competence later in life.
"Compared with those whose essays looked like Cicero with wonderful fluid prose nuns whose writing was laconic and brief were substantially more likely to have poor cognitive function and Alzheimer's disease 58 years later." This observation led to the hint that having a richer intellectual repertoire was protective to later life insult.
The Science series makes prominent mention of an unusual epidemiological opportunity that I was previously unaware of. (3) It details an effort in Scotland in which 70,000 11-year-old kids took a test on the same day in 1947. The exam's goal was to tease out which children were of high risk for poor performance in further educational effort.
Professor Ian Deary of the University of Edinburgh ambitiously retrieved the results of the IQ tests of 1641 of the original group 66 years earlier. Deary's group looked at an expanded inventory of connected data even including MRI scans of 1,000 of the cohort.
"A treasure trove" of data has spilled out of this detailed study. The most compelling of the results are displayed in a graph showing the trajectories of the scores after 70 years. Some went up, others down, ranging from -25 to + 25. The original IQ score could account for half of the later rate, meaning that the other 50 percent must have arisen somewhere along the way, stress, and major illness accounting for some of the deficits, while enrichments of various types continued to nourish the brain even until old age. The plasticity of our sentinel organ is clear.
Also apparent from the articles is the very strong influence of income on life expectancy, an issue that leads directly to the last article in the series, "Economic and Social Implications of Aging Societies" by demographers from Oxford.(4)
They stress how postponement of frailty and disability will reconfigure the status of nations into the near and distant future. On completing the series of articles I was heartened that a numb brain is unlikely in my future. In fact, I may even get smarter.
Hope lingers.
References:
1) Stern,P. The Aging Brain, Science, 2014;346:326-359.
2) Snowden D. et al. Linguistic Ability in early Life and Cognitive Function and Alzheimers Disease in Late Life , JAMA 1996, 275:528-532.
3) Underwood C. Starting Young, Science,2014:346:560-571.
4) Harper,S. Economic and Social Implications of Aging Societies, Science 2014 ;346: 587-591.