Probiotics Good for Fighting Alzheimer’s Disease

 

Growing evidence suggests that beneficial bacteria, also known as probiotics, could play a role in reversing Alzheimer’s disease. This approach is supported by experts’ increasing understanding of the human microbiome (the combined microorganisms residing on the surface and internally, including the gastrointestinal tract), the fact that gastrointestinal health has been linked to brain health and the idea that if we tackle the many factors that contribute to Alzheimer’s disease as a group instead of one at a time, we potentially have a chance to reverse early progression of the disease.
One of the growing number of researchers who embraces these notions and who has specifically studied the latter is Dr. Dale Bredesen, director of the Mary S. Easton Center for Alzheimer’s Disease Research at UCLA. He conducted a small (10 patient) novel therapeutic program that resulted in improvement in cognitive decline in nine of the participants. (The tenth patient had advanced Alzheimer’s when entering the program.) At the most recent follow-up done at two and one-half years, improvement was marked and sustained.
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Bredesen’s program is comprehensive, drug-free and addresses stress management, optimization of sleep, fasting, nutritional and herbal supplementation, a low glycemic/inflammatory/grain diet, regular exercise, hormone balancing and use of probiotics and prebiotics. According to Bredesen, his results “suggest that, at least early in the course, cognitive decline may be driven in large part by metabolic processes.”
Probiotics and the microbiota are a key part of those processes. Given that there are an estimated 100 trillion bacteria and up to 1,000 different bacterial species living in the human GI tract, it’s easy to understand why deciphering the connection may prove to be a challenge.
Thus far, research delving into the relationship between probiotics, cognitive decline and Alzheimer’s disease has been limited but the findings are revealing. For example, the GI tract is home to an abundant number of Lactobacillus and various Bifidobacterium species (common probiotics), which breakdown glutamate to produce GABA (gamma-amino butyric acid), a critical neurotransmitter in the central nervous system (brain and spinal cord).
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A short supply of GABA or its dysfunction is associated with cognitive impairment, depression and anxiety. Therefore, it’s reasonable to assume that an imbalance of good vs. bad bacteria in the gut (i.e., not enough probiotics) could contribute to an insufficient amount of GABA and thus cognitive decline.
Another example of a relationship between beneficial bacteria, the microbiome and cognitive decline concerns something called brain-derived neurotrophic factor (BDNF). Experts have noted that levels of BDNF are decreased in the brain of individuals who have Alzheimer’s disease. In experimental infection models that result in changes to the microbiota, expression of BDNF was reduced in the hippocampus (area of the brain involved with memory) of the test mice, and this reduction of BDNF is associated with progressive cognitive dysfunction.
In an animal study, a team of Iranian researchers gave probiotics to diabetic rats and then tested them with tasks involving memory and learning. From their observations they concluded that “probiotics efficiently reverse deteriorated brain functions in the levels of cognitive performances.”
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Researchers are still connecting the dots between probiotics and Alzheimer’s disease, so you won’t hear a lot of physicians recommending you include them as part of your dementia-prevention plan. However, given what we know thus far about their relationship and the fact that probiotics are also helpful for boosting the immune system, aiding digestive health, helping with urinary tract infections and women’s vaginal health and fighting allergies, among other benefits, including probiotics in your daily lifestyle seems like a wise choice.
On that note, according to neurologist David Perlmutter, MD, author of Grain Brain, emerging research is showing that eating foods rich in beneficial bacteria (e.g., yogurt, sauerkraut, kimchee, kefir, fermented vegetables) can influence brain behavior and may help with depression, anxiety and stress. Perlmutter also recommends choosing a probiotics supplement that contains at least 10 billion active cultures.

A research team from Iran are the first to show how a daily dose of probiotics for 3 months could be effective for improving memory and thinking abilities in individuals with Alzheimer's disease.

Researchers found older adults with Alzheimer's who drank probiotic-enriched milk showed improvements in cognitive functioning.

The researchers found that Alzheimer's patients who consumed milk enriched with beneficial live bacteria every day for 12 weeks showed significant improvements in cognitive functioning.
Senior study author Prof. Mahmoud Salami, from Kashan University in Iran, and colleagues recently published their findings in the journal Frontiers in Aging Neuroscience.
Probiotics are defined as live microorganisms that are "helpful" to human health. These include bacterial groups such as Lactobacillus and Bifidobacterium, as well as yeasts, including Saccharomyces boulardii.
According to the National Center for Complementary and Integrative Health, probiotics can act in a number of ways. They can help create a favorable community of microbes in the gut, for example, and help stimulate immune response.
Research has shown that these friendly microorganisms - many of which are added to food products, topical medications, and dietary supplements - may help protect against numerous infections and diseases, including irritable bowel syndrome (IBS), eczema, certain allergies, colds, and tooth decay.
Previous animal studies have also shown probiotics to improve learning and memory - an association that has been attributed to beneficial alterations in the gut microbiome that affect the brain. Whether probiotics have the same effect in humans, however, has been unclear.

Cognitive functioning scores improved with probiotics

For this latest study, Prof. Salami and team set out to determine the effects of probiotics on the cognitive functioning of 52 men and women aged 60-95 who had been diagnosed with Alzheimer's disease.
Participants were randomized to one of two groups. One group was required to drink 200 milliliters of normal milk every day for 12 weeks, while the other group drank 200 milliliters of milk containing four probiotic bacteria: Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus fermentum, and Bifidobacterium bifidum.

Fast facts about Alzheimer's

• More than 5 million adults in the United States are living with Alzheimer's
• Every 66 seconds, someone in the U.S. develops the disease
• Alzheimer's kills more people than breast cancer and prostate cancer combined.

Learn more about Alzheimer's

Before and after the 12-week study period, researchers collected blood samples from the participants, and the subjects' cognitive functioning was assessed using the Mini-Mental State Examination (MMSE) scale.
As part of this examination, subjects are required to complete a number of tasks that test learning and memory, such as naming objects, counting backward, and copying a picture.
Compared with participants who consumed the untreated milk, those who received the probiotic-enriched milk demonstrated significant improvements in cognitive functioning, the team reports.
Subjects who consumed the treated milk saw average MMSE scores increase from 8.7 to 10.6 (out of a possible 30) during the 12-week study period, while scores dropped from 8.5 to 8.0 for those who drank the untreated milk.
The researchers stress that all participants remained severely cognitively impaired, but their findings are the first to show that probiotics might lead to some cognitive improvements.
"In a previous study, we showed that probiotic treatment improves the impaired spatial learning and memory in diabetic rats," notes Prof. Salami, "but this is the first time that probiotic supplementation has been shown to benefit cognition in cognitively impaired humans."

Cognitive benefits of probiotics may be down to metabolic changes

On assessing the participants' blood samples, the researchers found that subjects who consumed probiotics had lower triglycerides levels, lower levels of "bad" very low-density lipoprotein (VLDL) cholesterol, and reduced high-sensitivity C-reactive protein - a marker of inflammation.
Additionally, participants who received probiotics showed a reduction in two measures of insulin resistance and the functioning of insulin-producing beta cells in the pancreas - HOMA-IR and HOMA-B.
The team says these findings indicate the cognitive benefits of probiotics may be down to the metabolic changes they provoke. "We plan to look at these mechanisms in greater detail in our next study," notes Prof. Salami. 

Walter Lukiw, a professor at Louisiana State University who was not involved in the study, hails the team's findings as "interesting and important," noting that they provide further evidence of a link between the gut microbiome and cognitive functioning.
"This is in line with some of our recent studies which indicate that the GI [gastrointestinal] tract microbiome in Alzheimer's is significantly altered in composition when compared to age-matched controls, and that both the GI tract and blood-brain barriers become significantly more leaky with aging, thus allowing GI tract microbial exudates (e.g. amyloids, lipopolysaccharides, endotoxins and small non-coding RNAs) to access central nervous system compartments," he adds.