Except in the cases of stroke or traumatic brain injury, loss of cognitive function is not something that happens all at once. Cognitive impairment that comes with age may be thought of as belonging on a continuum, with one end being no cognitive impairment and the other end being dementia, of which Alzheimer's is the most common type.
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The conventional view of brain development has been that most of this takes place in utero and in the first three years, with the further development continuing until the brain is fully mature at around 10-12 years of age. The turbulence of adolescent behavior has been deemed to be mostly caused by hormonal changes. Piaget, who identified four stages of cognitive development, assessed that his highest stage — that of formal, abstract reasoning — occurred around 13-14 years (although not everyone reaches this level, which requires appropriate education).
In October I reported on a study that found older adults did better than younger adults on a decision-making task that reflected real-world situations more closely than most tasks used in such studies. It was concluded that, while (as previous research has shown) younger adults may do better on simple decision-making tasks, older adults have the edge when it comes to more complex scenarios. Unsurprisingly, this is where experience tells.
Distributed practice more effective than massed practice
It has long been known that spacing practice (reviewing learning or practicing a skill at spaced intervals) is far more effective than massed practice (in one heavy session). An interesting example of this comes from a study that aimed to find the best way of teaching postmen to type (this was at the request of the British Post Office). The researchers put postmen on one of four schedules:
There was an alarming article recently in the Guardian newspaper. It said that in the UK, diabetes is now nearly four times as common as all forms of cancer combined. Some 3.6 million people in the UK are thought to have type 2 diabetes (2.8 are diagnosed, but there’s thought to be a large number undiagnosed) and nearly twice as many people are at high risk of developing it. The bit that really stunned me? Diabetes costs the health service roughly 10% of its entire budget.
I don't think anyone's going to try arguing that fruit and vegetables are not good for your health! We know they're good. But that's just general "oh, I know it's good for me" — do you know that the benefits are not only for your general health, your protection against obesity and diabetes, cancer and heart disease, but also for your brain. Actually, there's two aspects to this. An unhealthy diet (one rich in junk food, in saturated fat and sugar) is actively bad for your brain, and (the right) healthy diet is actively good for your brain.
Alzheimer's disease currently affects one in 10 people over age 65 and nearly half of those over age 85.
More than 19 million Americans say they have a family member with the disease, and 37 million say they know somebody affected with Alzheimer's.
In the United States, the average lifetime cost per Alzheimer patient is US$174,000. (These figures are from the U.S. Alzheimer's Association).
Retrieval practice, as its name suggests, is a simple strategy that involves retrieving the target information one or more times prior to testing. It is not the same as repetition or rehearsal! The idea is not to simply repeat the correct information, but to try and retrieve it. Feedback as to the correct answer may or may not follow.
I don't often talk about eyewitness testimony, but it's not because of the lack of research. It's a big field, with a lot of research done. When I say I don't follow it because I regard the main finding as a done deal - eyewitness testimony is useless - that's not meant to denigrate the work being done. There is, clearly, a great deal of value in working out the exact parameters of human failures, and in working out how we can improve eyewitness testimony. I just arbitrarily decided to ignore this area of research until they'd sorted it all out!
A study1 of nearly 2000 older adults has found that eating a Mediterranean diet was associated with less risk of developing mild cognitive impairment or of transitioning from MCI to Alzheimer's disease. The third with the highest scores for Mediterranean diet adherence had a 28% lower risk of developing MCI compared to the third with the lowest scores, and of those who already had MCI, those with the highest scores for Mediterranean diet adherence had a 48% less chance of developing Alzheimer’s.