Understanding Alzheimer’s Disease

Image © Shuttertsock/pathdoc
Image © Shuttertsock/pathdoc

Medical researcher and female health advocate, Dr. Emily Handley shares all the latest research on Alzheimer’s Disease ... without the jargon.

In science, every single day brings a new discovery – from a tiny change to a technique, to the big breakthrough that is the goal of all researchers. But this also means science is becoming harder to understand, with new acronyms and scientific jargon, and increasingly niche, specific topics. The titles of scientific papers are becoming longer, with denser summaries that make it difficult to fully comprehend the main points of published work. To keep you up to date with the latest in research – particularly in women’s health research – we’ve compiled some recent tid-bits of science goodness, made accessible without the jargon. Today we talk Alzheimer’s Disease.

What is Alzheimer’s Disease?

Alzheimer’s Disease is a degenerative disorder of our brains, where the cells in certain regions of our brain die. This results in memory loss, as well as behavioural and personality changes that greatly impact quality of life and require an increasing amount of care. In Australia, it is estimated that between 400,000 and 459,000 people are currently living with the disease, with almost two thirds of sufferers being women. We know that women live longer overall which may contribute to this higher incidence, but is this the only reason why they are overrepresented in Alzheimer’s cases? Interestingly, women are considerably more likely to develop Alzheimer’s post-menopause – and our favourite hormone, oestrogen, is suspected to play a role. With greater relevance for women, finding new ways to treat the disease and discover novel therapeutics is incredibly important as our population ages.

What events can lead to Alzheimer’s developing?

The disease is hugely multi-factorial, meaning that there are many different events, cellular populations and circumstances that lead to it developing. But what exactly are some of those clues and how can they be harnessed for future treatments?
  • The microbiome is the material of all biomes that live on and inside our bodies. Scientists have found increasing evidence for a ‘microbiota-gut-brain axis’ and to explore this further, studies are now linking cognitive ability with the microbiome of the gut. Recently, Daniel Cuervo-Zanatta and colleagues identified sex differences in the cognitive skills of old mice, with healthy, older females performing better than males. To try to understand what controls this sex and disease-dependent performance, they examined the gut microbiome of these mice. What they found was that the composition of the microbiome – that is, the biome species in the stomach of these mice – are associated with and regulate improved working and object-recognition memory in older female mice. These kinds of findings – that the biodiversity of the gut microbiome could be linked to our ability to think and remember – have been replicated, where the composition of the microbiome in normal and Alzheimer’s-affected mice corresponds to performance measures in cognitive tasks.
  • We can learn much about Alzheimer’s development by studying healthy centenarians – those aged 100 years and over who are still cognitively ‘healthy’. The good news: 70-80% of cognitively healthy centenarians are women, identified in a study from the Netherlands. And when a person’s thinking and processing capacity is higher, Beker and colleagues found that life-expectancy and survival increased with it. Accordingly, the latest models of Alzheimer’s mutations – genes that induce inherited forms of the disease – also display sex differences, where females have preserved communication between cells and higher cognitive performance.
  • Sleep is increasingly recognised as a vital component of our brain health. Some scientists believe that ‘slow-wave’ activity in the brain – seen during periods of sleep – is the default state of our brains, where memory centres can consolidate information. In mice with Alzheimer’s mutations, neurons in the hippocampus (the region responsible for memory) lose the ability to return to this default state during sleep. This change in activity may in fact occur before we see overt sleep disturbances in people developing dementia. Sleep is also when our glymphatic system is hard at work clearing waste and debris from our brains. The glymphatic system uses fluids to remove harmful waste products primarily during sleep, and plays a major role in Alzheimer’s development. When sleep is disturbed, this vital process is disturbed – further exacerbating Alzheimer’s onset and progression.
  • Our brain’s use many different avenues to clear out waste, including the systems mentioned above. Autophagy is the process of clearing dying or defective cells from the brain, and this process slows in people aged over 65. If proteins that function inside our cells break down and aren’t removed correctly, they can accumulate and become the characteristic protein ‘clumps’ that appear in Alzheimer’s-affected brains. Recent studies suggest it might be this process that then triggers a cascade of disease events that manifest as dementia. Even more interesting? We have evidence that women are particular vulnerable to a breakdown in autophagic processes after menopause, which may contribute to the increased risk women face in developing the disease after the loss of circulating sex hormones.
  • Good news for coffee addicts! In an Australian study, researchers from Edith Cowen University found that people without memory impairments and high coffee intake may have a reduced risk of developing a condition called mild cognitive impairment. This condition often precedes Alzheimer’s disease. Coffee also increased performance in cognitive function – particularly in planning and attention – and even seemed to slow the accumulation of disease proteins in the brain. Much more research is needed though, so think twice before upping those cups of coffee; we still need to understand how caffeine interacts with Alzheimer’s events in our brains before we can advise any lifestyle changes.
  • Finally, there are new findings of the benefits of exercise in mediating the risk of Alzheimer’s dementia. When investigating how our blood can regulate brain function, studies have linked more exercise with greater brain cell health. Additionally, the mice that did not exercise had greater levels of inflammation present throughout the brain, a phenomenon that was reduced when exercise was introduced. The link between exercise and decreased inflammation in the Alzheimer’s brain has been identified through a range of cell pathways recently, and increasingly shows how important physical activity is for our brain health. While we’ve known for some time that physical exercise can reduce the risk of Alzheimer’s disease and cognitive decline, research continues to understanding the ways we can turn this into effective treatments.
The take-away message? Every day we gain a greater understanding of the events that lead to Alzheimer’s developing. Women have a greater risk of developing the disease after menopause and finding out why this may be the case is a key to therapeutics.

This article provides general information only, and does not constitute health or medical advice. If you have any concerns regarding your health, seek immediate medical attention.