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An acceleration of cognitive decline?

26 Jun

Here a disturbing finding published in the most recent issue of the journal Intelligence, I have underlined the key sentence :

The cohort process of cognitive aging is a contested topic in population research. The literature is largely in disagreement over how and why inter-cohort trends in cognitive aging occur in the United States. This paper examines significant trends in the rate of cognitive decline and conceptualizes the role of the depression trajectory as a late life course process that accelerates cognitive aging at the individual and population level. To this end, I draw my study sample from the Health and Retirement Study (N = 24,678) and use aging-vector models as an extension of parallel-process latent growth modeling to analyze repeated measures of cognition and depression. Findings show the acceleration of cognitive decline (“negative” Flynn Effect) and worsening of depression risk for recent cohorts. The upward trends in depression account for significant acceleration in cognitive decline among later cohorts, thus providing a new insight into sociogenic population dynamics of cognitive aging.

From the body of the paper:

Taken together, the findings of the study strongly support the “negative” Flynn Effect on cognitive aging (Alwin, 2008). That is, later cohorts not only perform cognitive tasks more poorly, but also experience a faster rate of cognitive decline. As a result, considerable intercohort gaps occur particularly in old age. Further, the present study shows that the acceleration of cognitive decline is largely driven by depression symptomatology that concurrently evolves in late life, rather than by differences in cognitive reserves during adulthood (e.g., socioeconomic environments). Thus, the negative Flynn Effect is not necessarily paradoxical with regard to a continuous increase in educational attainment, which does not significantly predict the rate of cognitive decline. In contrast, depression risk in later life have significant impacts on cognitive decline at the individual and population levels. The results show that individuals develop an average of 1 to 2 additional depression symptoms in late life. Because later cohorts, particularly Non-Hispanic Blacks and Hispanics, are at higher risk of developing depression symptoms, their exposure to cognitive risk factors should be of public health concern.

Dementia rates fall

23 Nov

A very surprising finding reported in The New York Times:

Despite fears that rates were going to explode as the population grows older and fatter, and has more, a large nationally representative survey has found the reverse. Dementia is actually on the wane. And when people do get dementia, they get it at older and older ages.

You can read the original study here. The key points:

Question Has the prevalence of dementia among older adults in the United States changed between 2000 and 2012?

Findings In this observational cohort study of more than 21 000 US adults 65 years or older from the nationally representative Health and Retirement Study, dementia prevalence declined significantly, from 11.6% in 2000 to 8.8% in 2012.

Meaning Population brain health seemed to improve between 2000 and 2012; increasing educational attainment and better control of cardiovascular risk factors may have contributed to the improvement, but the full set of social, behavioral, and medical factors contributing to the improvement is still uncertain.

What are the causes of this good news?:

Increases in the level of education among the later-born cohort accounted for some of the decreased dementia risk, and there was some evidence that improvements in treatments for cardiovascular risk factors (eg, diabetes) may also have played a role. However, the full set of social, behavioral, and medical factors contributing to the decline in dementia prevalence is still uncertain.

James Flynn on the Flynn Effect

24 Oct

I showed this video to my doctoral students last week. It’s a nice summary of Flynn’s work. I regard the Flynn Effect as one of the most important discoveries, a greatest mysteries, of scientific psychology.

Special brag point: I am the author of the study he mentions on Ohio school examinations.

Against generation labeling

28 Mar

When I was a teenager one of the most irritating things adults would say was some version of “it’s up to you young people to solve the world’s problems.” I always wanted to respond “what, are you dead?”

Obviously some cohort effects exist, how else could you explain the Flynn Effect? But generation talk is often superficial stereotyping. We call one cohort, “The Greatest Generation.” Really? Everyone in the generation was great? Sure some of them fought in World War II, but some of them also caused the war.

In any event, I enjoyed watching Adam Conover eviscerate generational labeling:



Hat tip to BoingBoing

Cohort effects

7 Jan

Last year, I heard Tom Brokaw speak at Chautauqua about his book The Greatest Generation.  I don’t want to disparage or discount in anyway the heroism and sacrifice of so many people, but I am always a little bit uneasy about generational talk. After all there were plenty of people in that generation who did not behave bravely, indeed, there were Americans of that generation who actively supported Hitler. Before you make any generalization about a generation, think about the vast range of behaviors among your own contemporaries.

That being said, it would be surprising if there were no cohort effects. The Flynn Effect, for example, shows that cognitive change can occur over the generations. We would expect that changing technologies, educational practices, social mores, and the cumulative experience of the past would have psychological consequences.

Here is a recent article from The Observer, a publication of the Association for Psychological Science, that reviews the research on cohort effects and the related controversies:

 “We tend to view our preferences and idiosyncrasies as inherently singular — a unique cocktail of traits that emerges from mixing genetic predispositions with our familial and social experiences. But ever since Karl Mannheim proposed his theory of generations in a seminal 1923 essay, researchers have tried to elucidate the influence of the sociocultural environment — including those influences unique to each generation — on aspects of our personalities and attitudes.
This work is not without its skeptics. Many social scientists regard the evidence of birth cohort effects on the individual to be inconclusive at best. But others believe they have uncovered some clear, collective traits that distinguish one age group from another.”


James Flynn: Are we getting smarter?

25 Sep

Here is an interview with James Flynn as part of the promotion for his book Are We Getting Smarter?: Rising IQ in the Twenty-First Century. Flynn is most famous for his discovery of what is now called the Flynn Effect, the observed substantial increase in IQ scores over time.


[Full disclosure: My research is cited on page 15 of this book]

Dementia rate falls in Denmark, England and Wales

17 Jul

Good news. Gina Kolata reports in the New York Times that two studies, one conducted in England and Wales, the other in Denmark have found falling rates of Dementia.

Why has the rate of dementia declined? One interesting possibility is the Flynn Effect, the observation that average IQ scores have risen substantially over time. IQ and dementia are inversely correlated, in other words the higher your IQ the lower your risk of dementia. Other explanations might be better health and better education, which also are correlated with lower dementia risk.

However, some caution is in order, the increase in obesity and type II diabetes we have observed in recent decades may counteract this positive trend as the population ages.

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