Old honeybees can regain youthful cognition when they return to youthful duties

August, 2012
  • A honey bee study shows how old foraging bees quickly start to decline cognitively, and how this can be reversed in some if they return to more social domestic duties in the hive.

I often talk about the importance of attitudes and beliefs for memory and cognition. A new honey bee study provides support for this in relation to the effects of aging on the brain, and suggests that this principle extends across the animal kingdom.

Previous research has shown that bees that stay in the nest and take care of the young remain mentally competent, but they don’t nurse for ever. When they’re older (after about 2-3 weeks), they become foragers, and foraging bees age very quickly — both physically and mentally. Obviously, you would think, bees ‘retire’ to foraging, and their old age is brief (they begin to show cognitive decline after just two weeks).

But it’s not as simple as that, because in artificial hives where worker bees are all the same age, nurse bees of the same age as foragers don’t show the same cognitive and sensory decline. Moreover, nurse bees have been found to maintain their cognitive abilities for more than 100 days, while foragers die within 18 days and show cognitive declines after 13-15 days (although their ability to assess sweetness remains intact).

The researchers accordingly asked a very interesting question: what happens if the foragers return to babysitting?

To achieve this, they removed all of the younger nurse bees from the nest, leaving only the queen and babies. When the older, foraging bees returned to the nest, activity slowed down for several days, and then they re-organized themselves: some of the old bees returned to foraging; others took on the babysitting and housekeeping duties (cleaning, building the comb, and tending to the queen). After 10 days, around half of these latter bees had significantly improved their ability to learn new things.

This cognitive improvement was also associated with a change in two specific proteins in their brains: one that has been associated with protection against oxidative stress and inflammation associated with Alzheimer disease and Huntington disease in humans (Prx6), and another dubbed a “chaperone” protein because it protects other proteins from being damaged when brain or other tissues are exposed to cell-level stress.

Precisely what it is about returning to the hive that produces this effect is a matter of speculation, but this finding does show that learning impairment in old bees can be reversed by changes in behavior, and this reversal is correlated with specific changes in brain protein.

Having said this, it shouldn’t be overlooked that only some of the worker bees showed this brain plasticity. This is not, apparently, due to differences in genotype, but may depend on the amount of foraging experience.

The findings add weight to the idea that social interventions can help our brains stay younger, and are consistent with growing evidence that, in humans, social engagement helps protect against dementia and age-related cognitive impairment.

The (probably) experience-dependent individual differences shown by the bees is perhaps mirrored in our idea of cognitive reserve, but with a twist. The concept of cognitive reserve emphasizes that accumulating a wealth of cognitive experience (whether through education or occupation or other activities) protects your brain from the damage that might occur with age. But perhaps (and I’m speculating now) we should also consider the other side of this: repeated engagement in routine or undemanding activities may have a deleterious effect, independent of and additional to the absence of more stimulating activities.

Reference: 

Related News

As we all know, people are living longer and obesity is at appalling levels. For both these (completely separate!) reasons, we expect to see growing rates of dementia. A new analysis using data from the long-running Framingham Heart Study offers some hope to individuals, however.

A study involving 39 older adults has found that those randomly assigned to a “high-challenge” group showed improved cognitive performance and more efficient brain activity compared with those assigned to a low-challenge group, or a control group.

Data from 2,800 participants (aged 65+) in the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) study has revealed that one type of cognitive training benefits less-educated people more than it does the more-educated.

A study involving 266 people with mild cognitive impairment (aged 70+) has found that B vitamins are more effective in slowing cognitive decline when people have higher omega 3 levels.

Growing research has implicated infections as a factor in age-related cognitive decline, but these have been cross-sectional (comparing different individuals, who will have a number of other, possibly confounding, attributes).

Another study adds to the growing evidence that a Mediterranean diet is good for the aging brain.

A two-year study which involved metabolic testing of 50 people, suggests that Alzheimer's disease consists of three distinct subtypes, each one of which may need to be treated differently. The finding may help explain why it has been so hard to find effective treatments for the disease.

A study involving both mice and human cells adds to evidence that stress is a risk factor for Alzheimer's.

Data from 23,572 Americans from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study has revealed that those who survived a stroke went on to have significantly faster rates of cognitive decline as they aged.

A study involving 382 older adults (average age 75) followed for around five years, has found that those who don’t get enough vitamin D may experience cognitive decline at a much faster rate than people who have adequate vitamin D.

Pages

Subscribe to Latest newsSubscribe to Latest newsSubscribe to Latest health newsSubscribe to Latest news