Tensions between the brain and gut and the composition of the microbiome appear to play a critical role in the development of neurodegenerative conditions.
Although evidence supporting a link between the small gut-brain axis (MGBA) and Alzheimer's disease continues to grow, the exact mechanism behind the relationship is still poorly understood.
Using the largest ever study of the genome of human intestinal bacteria, a team of researchers from the US sought to find a clearer relationship between Alzheimer's disease and the mix of organisms that live within the digestive tract.
The analysis not only revealed a genetic link between different genera of gut bacteria and a diagnosis of Alzheimer's disease, but also revealed a link between the microbiome and a genetic risk factor for the neurodegenerative disorder.
The study also underscores the interaction between genetic factors and inflammatory gut bacteria in healthy brain function.
Experts explained that early in our development, our bodies are colonized by a variety of bacteria, fungi and viruses that hold a temporary truce with the immune system. Microbes get a place to live, and we get a front line of defense from invading elements into our bodies.
But, shifts in our immune system can give some species an advantage over others. Likewise, changes in the composition of the microbiome—for example, through shifts in our diet—can profoundly affect the body's functioning, for better or for worse.
In recent years, researchers have focused on this complex relationship between gut bacteria, the immune system, and neurological functioning, trying to understand why areas of the brain deteriorate and cause symptoms of memory loss and cognitive decline that we call Alzheimer's disease.
Observational studies have revealed a decrease in the diversity of gut microbes in individuals diagnosed with the condition, while analyzes have shown that gut bacteria can release chemicals that may stimulate harmful inflammatory signals in the brain.
In addition, there is a gene involved in the movement of fats through the blood, known as apolipoprotein E (APOE). The variant known as E4 appears to represent a genetic risk for Alzheimer's disease.
There is good reason to suspect that the presence of at least one copy of APOE E4 may have some influence on the composition of our microbiota.
In this regard, the team examined detailed records of 119 bacterial genera based on a study that included thousands of participants, known as the MiBioGen Consortium.
Initial research into bacterial genes that could be linked to Alzheimer's disease has revealed about 20 genera suspected of playing some role in the development of the disease. A second search through a more restricted sample produced 10 genera, six of which were less frequent among diagnosed patients, and the remaining four more common.
Four of them appear to be associated with the APOE allele, which is thought to increase the risk of Alzheimer's disease.
For example, Actinobacterium Collinsella is associated with Alzheimer's disease and the APOE variant, as well as rheumatoid arthritis, atherosclerosis, and type 2 diabetes.
The researchers suspect that Collinsella's ability to enhance the expression of inflammatory messenger hormones could play a role in exacerbating - if not triggering - neurological damage.
This research was published in Scientific Reports.
Revealing the key to brain health in old age!
A new study has found that people in later stages of life who participate in aerobic activities and strength training exercises perform better on cognitive tests than others.
The researchers evaluated 184 cognitively healthy people, ages 85 to 99, with each participant reporting their exercise habits and undergoing a comprehensive battery of neuropsychological tests designed to assess different dimensions of cognitive function.
They found that those who incorporated aerobic exercise, such as swimming and cycling, and strength exercises such as lifting weights into their routine, had better mental agility, faster thinking, and a greater ability to change or adapt their thinking.
Using the Montreal Cognitive Assessment tool, which provides a balanced view of many aspects of cognition, researchers discovered that people who did not participate in any physical exercise scored lower than those who did cardio and strength training.
The results indicate that engaging in a variety of exercise is associated with improved cognitive performance in people in their late 80s and beyond.
The results provide an evidence base for healthcare providers to consider recommending a mixed regimen of aerobic and strength training as part of their patients' wellness plans.
The study was conducted as part of a large, multi-site collaboration with the McKnight Brain Research Foundation, which has institutes at the University of Florida, the University of Miami, the University of Arizona, and the University of Alabama-Birmingham.
Report prepared by Brian Ho, doctoral candidate in clinical and health psychology, and Ronald Cohen, professor of clinical and health psychology, University of Florida.
The study was published in the journal GeroScience.
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