Medical science has done exceedingly well in extending our lifespans, with the average age of death literally decades more than it was a century ago. But is the longer lifespan really worth it if our health can’t keep up? We’ve made little to no headway in stopping or delaying the onset of dementia, and although increasing numbers of people are living into their nineties, it’s estimated that around two-thirds of them have either dementia or mild cognitive impairment.
Most researchers working on dementia, and in particular Alzheimer’s, have focused on identifying disease pathology and pathogenesis, which they hope may lead to the development of drugs to target markers. But some have taken the opposite route, and have chosen to look at a rare group of people who live into their eighties and nineties but have the cognitive abilities of someone several decades younger. These are the so-called ‘superagers’.
Two studies recently presented at the American Association for the Advancement of Science focus on this group of healthy agers. One study showed significant anatomical differences in the brains of superagers, demonstrating that they shrink much more slowly than age-matched controls. Over 18 months the control brains lost volume in the cortex twice as fast as those of the superagers, making them less resistant to cognitive impairment and dementia.
The study also found that superagers have more of a type of cell known as the Von Economo (VE) neuron than normal elderly people. These VE neurons are found in the anterior cingulate, which is thought to play a role in attention and working memory. Researchers also found that anterior cingulate is considerably thicker in superagers. It’s not yet clear why superagers have more of these VE neurons and what role they play in improving the cognitive abilities of superagers.
Autopsy studies of superagers have also in some ways muddied the waters of Alzheimer’s research, as they show that superagers are not immune to the plaques of amyloid protein that are the hallmarks of the disease. Why some people who have amyloid pathology develop the cognitive impairments typical of Alzheimer’s disease, while some don’t, is not yet clear. But the finding may have some relevance as to why experimental drugs designed to clear amyloid from the brain have not to date proven successful in phase 2 and 3 trials in humans. It also might point to the fact that lifestyle factors play a more important role than previously suspected.
Do the superagers have anything to tell us about how we can increase our chances of a cognitively healthy old age? Another study – the 90+ Study, has been tracking people in their 90s for the past 15 years to try and elucidate whether there are any particular lifestyle patterns in those who live well in their older years. And it turns that there are.
One factor that seems to play an important role is having strong social networks. Superagers reported having more satisfying, high-quality relationships compared with cognitively average people of the same age. The finding mirrors that of several other studies that found social interactivity is a crucial predictor of longevity and delay of cognitive impairment.
Here are some other key findings of the 90+ study:
- People who drank moderate amounts of alcohol or coffee lived longer than those who abstained;
- People who were overweight in their 70s lived longer than normal or underweight people did;
- Over 40% of people aged 90 and older suffer from dementia, and almost 80% are disabled. Both dementia and disability are more common in women than men;
- About half of people with dementia over age 90 do not have sufficient neuropathology in their brain to explain their cognitive loss;
- People aged 90 and older with an APOE2 gene are less likely to have clinical Alzheimer’s dementia, but are much more likely to have Alzheimer’s neuropathology in their brains.