How Bees Are Helping Us in the Fight Against Dementia
The average bee’s brain contains somewhere around 950,000 neurons. It is the size of a sesame seed. By comparison, a human brain has a ballpark 100 billion neurons, with the capacity for language, consciousness, philosophical thought, and at its high-performing best, creating works like “The entire bee movie but every time they say bee it gets faster” (which at time of writing, sits at almost 16k views on YouTube). These differences aside, recent studies focusing on the fuzzy insects’ noggins are providing exciting clues which may help us better understand and ultimately combat deadly neurodegenerative diseases like dementia.
We are at a critical point to advance the fight – against Alzheimer’s in particular, dementia’s most widespread form,
for which there is no known cure. Causing the brain’s outer cortex to shrink from progressive cell death, the disease results in the impairment of memory, language, and various other faculties which are fundamental to identity and day-to-day wellbeing. In the United States, Alzheimer’s is the sixth leading cause of death, with 5 million estimated sufferers. Many more are affected however – in particular caregivers and families, who will spend countless (unpaid) hours tending to a loved one who, when the disease sets in, may no longer be recognizable as the person they’ve known all their lives, or even remember their name.
With a global ageing population, the number of individuals impacted by dementia is certain to grow, along with the human, emotional and financial costs. Last year, it hit U.S. health care by $236 billion. By 2050, this could rise to $1 trillion.
How can honey bees help? Though simple in structure, bees are a ‘good’ kind of dense – having a neural density of more than ten times that in a mammal’s cortex. They have “an amazing capacity to learn and remember,” attests Dr Stephanie Biergans, University of Queensland researcher and leading author of a study released by Frontier science journal late last year. “They can count up to four, and orientate themselves by learning patterns and landmarks. They are also social insects that interact, teach and learn, making them successful foragers. Bees remember how to find a food source, how good the source was, and how to return to the hive.”
What makes them most valuable to dementia research however is the sophisticated parallel mechanisms shared between our two species. Relevant here is a process known as DNA methylation – an ‘epigenetic mechanism’, meaning that it works by turning ‘off and on’ certain parts of the genome as a function of the environment. Neurons are included in the cells affected by DNA methylation. In other words, the state of bee and human brains (along with the expression of millions of other DNA ‘instructions’) is not pre-determined by an unalterable hereditary lot. Our changing external environment also defines us – how we develop when we’re young, how we age over time, the manner in which certain programmed traits may manifest, and the course certain diseases may take.
To better test this on bees, Biergans’ study mimicked real-life learning conditions, teaching bee test groups “to associate an odor with a sugar reward, similar to the olfactory learning taking place when a bee collects nectar from a flower during foraging.” When a connection between a certain scent and a ‘treat’ reward was made, the bee would stick out its tongue (or proboscis) as soon as it picked up on the scent. This is long-term memory-making in action – which occurs when a molecular neural connection becomes a structural connection, and is built up and consolidated by regular localized electrical activity over time.
Yet when the researchers blocked the methylation process (applying chemical inhibitors used in cancer treatment), bees struggled to respond to the conditioning. Their ability to form long-term memories was virtually nixed. What the results suggest, then, is that epigenetics performs a key role in regulating the specificity of memory and the process of re-learning.
“By understanding how changes to the epi-genome accumulate, manifest and influence brain function, we may, in the future, be able to develop treatments for brain diseases that also develop over a lifetime,” concludes Biergans. “There is thought to be a genetic predisposition for some conditions, such as Alzheimer’s and dementia, but in many cases environmental factors determine whether the disease will manifest.”
The brain – of humans and bees – is still a mystery to science, yet the work of research scientists paired with new technology is seeing this mystery recede every day. There is, for instance, now a CT scanner so small we can put a bee inside it. Another dementia-related study conducted in 2012 found that simply by taking on roles typically assigned to younger bees, older bees were able to revitalize short-term memory circuits and re-learning competencies – essentially reversing the brain aging process. The results made a powerful case for using social methods – which promote mental wellbeing through regular interaction – to treat dementia, rather than a blanket medication approach.
Perhaps bees can help us most, however, if we consider them very small role models to good health. Among the top preventative lifestyle factors which contribute to dementia, it is inactivity that’s the main killer. Like the bee then, if we want to keep our wits about us for as long as we can, it’s best to keep busy.
By Kate Prendergast