Alzheimer's disease: How gut bacteria may play a role

Evan Walker
Evan Walker TheMediTary.Com |
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Experts say a healthy diet is important for older adults. RgStudio/Getty Images
  • Researchers report that gut microbiota might play a role in the development of Alzheimer’s disease.
  • They say gut bacteria transferred from humans into rats produced some signs of dementia in the animals.
  • The researchers said they hope their findings can eventually help in the development of methods to diagnose Alzheimer’s earlier.

Scientists are reporting that gut microbiota may play a role in the development Alzheimer’s disease, according to a new study published in the journal Brain.

In their study, the researchers transferred gut bacteria, via fecal transplants, from individuals with Alzheimer’s disease to young, healthy rats.

The researchers reported that after the transplants the animals showed some signs of dementia, including producing fewer new nerve cells and exhibiting impaired memory.

The study authors note that people with Alzheimer’s usually do not receive a diagnosis until after the onset of cognitive symptoms. Earlier diagnosis would allow treatments to start sooner.

“Alzheimer’s is an insidious condition that there is yet no effective treatment for. This study represents an important step forward in our understanding of the disease, confirming that the make-up of our gut microbiota has a causal role in the development of the disease,” said Dr. Sandrine Thuret, a professor of Neuroscience at King’s College London and one of the study’s senior authors, in a press statement. “This collaborative research has laid the groundwork for future research into this area and my hope is that it will lead to potential advances in therapeutic interventions.”

More than 6 million people in the United States live with Alzheimer’s disease and that is projected to increase to 13 million by 2050.

Alzheimer’s disease is the most common type of dementia, according to the Centers for Disease Control and Prevention.

It affects parts of the brain that control thought, memory, and language. Early symptoms include mild memory loss. Late in the disease, people may have difficulty conversing or responding appropriately to their environment.

Scientists do not fully understand the causes of Alzheimer’s. They are currently studying whether education, diet, exercise, and environment could contribute to a person developing the disease. Some evidence shows that Healthy behaviors might reduce the risk of cognitive decline.

Many people see memory loss and other early warning signs as normal for aging and do not seek medical help.

Some of the early warning signs include:

  • Memory loss that disrupts daily life. For example, getting lost in a familiar place or repeating questions.
  • Difficulty paying bills and handling money.
  • Problems completing familiar tasks at home or work.
  • Misplacing things and being unable to retrace steps.
  • Changes in mood, personality, or behavior.

If someone exhibits some of these signs, it doesn’t mean they have Alzheimer’s. It does indicate that they should see a doctor.

Possible other causes for these symptoms include vitamin B12 deficiency and side effects of medication.

A review of studies published in 2022 found that systemic inflammation, partly influenced by gut microbiota, could lead to as well as worsen the progression of Alzheimer’s.

Diets, such as the MIND diet, can reduce the risk of developing Alzheimer’s, according to the National Institute on Aging.

“The MIND diet has been shown to reduce Alzheimer’s risk, dementia, and cognitive decline,” said Anne Danahy, a registered dietitian nutrition with a master’s degree in food and nutrition science. “It’s a mashup of the Mediterranean and DASH diets, which are also anti-inflammatory diet patterns, but the MIND diet seems to be even more beneficial for brain health than either one of those diets alone.”

Danahy told Medical News Today the MIND diet is “extremely flexible and easy to follow. She listed the suggested guidelines from this eating plan:

  • 3+ servings a day of whole grains (oats, wild rice, quinoa, millet, whole grain bread)
  • 6+ servings a week of green leafy vegetables (spinach, kale, arugula, Swiss chard, etc)
  • 1+ servings a day of any other kind of vegetable
  • 2+ servings a week of berries
  • 5+ servings a week of nuts (a serving is about a handful)
  • 4+ meals a week of beans
  • 2+ meals a week of poultry
  • 1+ meals a week of fish (preferably fatty fish like salmon or sardines
  • Olive oil

She also recommended reducing the amount of these foods:

  • Pastries and sweets
  • Red meat (including beef, pork, lamb, and products made from these meats)
  • Fried foods
  • Cheese
  • Butter/stick margarine

“Another important inflammation booster is chronic stress, so anyone who feels like they’re in that constant fight-or-flight state should work on ways to reduce stress,” Danahy added.

She said it’s important to try various techniques to find out what works best for you. She recommended these activities:

  • Yoga or tai chi
  • Hiking or walking (outside in nature vs on the treadmill)
  • Meditation
  • Breathwork
  • Journaling
  • Stop scrolling and texting
  • Aim for 7-9 hours of sleep each night

“One other thing to add is that following an anti-inflammatory diet pattern and reducing stress are not only good for your brain but they are also associated with a more diverse microbiota,” Danahy noted.

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