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

A study involving more than 2,500 older adults (65+) found that the rate of worsening vision was associated with the rate of cognitive decline. More importantly, vision has a stronger influence on cognition than the reverse.

Hearing loss linked to increased dementia risk

Chronic insomnia linked to memory problems

Link found between chronic inflammation and Alzheimer's gene risk

Brain scans of 9,772 people aged 44 to 79, who were enrolled in the UK Biobank study, have revealed that smoking, high blood pressure, high pulse pressure, diabetes, and high BMI — but not high cholesterol — were all linked to greater brain shrinkage, less

A large Chinese study involving 20,000 people has found that the longer people were exposed to air pollution, the worse their cognitive performance in verbal and math tests. The effect of air pollution on verbal tests became more pronounced with age, especially for men and the less educated.

A review of 34 longitudinal studies, involving 71,244 older adults, has concluded that depression is associated with greater cognitive decline.

A study following nearly 28,000 older men for 20 years has found that regular consumption of leafy greens, dark orange and red vegetables and berry fruits, and orange juice, was associated with a lower risk of memory loss.

Poor sleep has been associated with the development of Alzheimer's disease, and this has been thought to be in part because the protein amyloid beta increases with sleep deprivation. A new study explains more.

A small study has found that a 12-week exercise program significantly improved cognition in both older adults with

Pages

Subscribe to Latest newsSubscribe to Latest newsSubscribe to Latest health newsSubscribe to Latest news
Error | About memory

Error

The website encountered an unexpected error. Please try again later.