This news release describes the results of a randomized controlled trial that examined the effects of milk supplemented with probiotic bacteria on cognitive function and metabolic status (the whole range of biochemical processes that occur within the body) in individuals with Alzheimer’s disease.
Fifty-two men and women, aged 60-95 years, consumed either milk (the control group) or milk with a mixture of probiotics (the probiotic group) for 12 weeks. Cognitive function was assessed using the Mini-Mental State Examination (MMSE) and metabolic endpoints were measured through blood samples. The news release presented an accurate description of the study design, provided conservative explanations of the improvements seen in the intervention group, and emphasized the need for more research. However, it did not discuss several important aspects — namely, the cost and availability of the probiotic milk, potential harms of probiotic supplements in certain populations, and alternative therapies for treatment of Alzheimer’s symptoms. Interpretation of the results was also inaccurate, leaving this news release with quite a bit of room for improvement.
Alzheimer’s disease is the most common type of dementia, a general term used to describe various diseases and conditions that damage brain cells. Despite decades of research and improvements in quality of life for people living with this condition, ultimately Alzheimer’s is fatal and currently there is no cure. Therefore, potential dietary interventions to improve cognitive function are of interest.
Drug development studies are underway to identify new treatments to stop, slow, or prevent Alzheimer’s, but because new drugs take years to produce — and because drugs that seem promising in early-stage studies may not work as hoped in large-scale trials — complementary and alternative therapies are an attractive option for Alzheimer’s patients.
This study is the first clinical trial to evaluate the effects of probiotic supplementation on cognitive function in patients with Alzheimer’s disease, and researchers cautiously suggested that their findings may point toward a mechanism by which probiotics affect Alzheimer’s and possibly other neurological disorders. Although this study yielded promising results, the news release neglected to highlight the fact that the probiotic milk used as the study intervention is not available to the general population and did not provide any reference to assess the clinical relevance of the improvement in cognitive symptoms.
The cost of the intervention isn’t mentioned, and there’s no assessment of how the cost might compare with other medications prescribed to treat the cognitive symptoms of Alzheimer’s disease. It should also be noted that this intervention, if it were available to purchase, would likely be a long-term, continual investment. Probiotic bacteria are known to be transient “passers through” in the gastrointestinal tract, so a person would need to continue to purchase and consume the beverage for as long as they hoped to see results. Probiotics also tend to be relatively expensive, with the capsules now on the market typically costing about 50 cents to $1 per pill.
The news release states that over the 12-week intervention period, “the average score on the MMSE questionnaire significantly increased (from 8.7 to 10.6, out of a maximum of 30) in the group receiving probiotics, but not in the control group (from 8.5 to 8.0).” While the exact numeric values are correct, and the release is to be applauded for attempting to quantify the results (even going so far as to include the range of the scale being used — very helpful), the word “significantly” is incorrectly applied in this statement. The MMSE scores at the end of the study are being compared between groups — not within the same group. A correct comparison might read, “When comparing the change in MMSE scores over the 12-week study, there was a statistically significant difference between the two groups- – the intervention resulted in an improvement in MMSE score in the probiotic group compared to the control group.” The researchers phrased it right in the original publication, but the news release misinterpreted the finding.
Ideally, the release (as well as the published study) would have discussed what the improvement in MMSE scores means to an individual with Alzheimer’s. Authors stated that “all patients remained significantly cognitively impaired” — so what effect would a two-point increase in MMSE have on a person’s daily life? It would be beneficial for readers to understand the clinical and personal significance of these improvements.
Although probiotics are considered to be safe for people who are generally healthy, they have been linked to severe side effects in people with underlying medical problems. According to the National Institutes of Health, the populations most vulnerable to adverse effects from probiotics include the critically ill, infants, and people with weakened immune systems, which often includes elderly men and women. Since this study was conducted in individuals aged 60-95 years with an underlying health condition, safety should have been addressed in the news release. And yet, no explanation of risks or potential harms was provided.
Evaluation of all treatments, including benign appearing supplements, should include an assessment of harm.
Although it obliquely references the small size and short duration of the study, the news release didn’t really call attention to study limitations, which also include a reliance on only one set of criteria for assessment of cognitive function and the fact that bacterial loads in stool samples before and after probiotic supplementation were not compared. This important comparison could help in determining how well the probiotic bacteria were “taking hold” in the gut rather than just passing through. Without this information, it’s not possible to know if the probiotics influenced the relative composition of the gut microbiome or the functions of its inhabitants.
The news release essentially does the opposite of disease mongering. It does not describe what Alzheimer’s disease is or who may be at risk. While this information would be helpful for readers, it is also prudent that they did not overreach on who may be affected by the disease.
The news release states that the research was supported by a grant from the Deputy of Research of Kashan University of Medical Sciences, and that the probiotic supplements were produced and provided by Tak Gen Zist Pharmaceutical Company in Tehran, Iran. The authors declared no commercial or financial relationships that could be construed as a potential conflict of interest.
Although there is no cure for Alzheimer’s, several drug and non-drug options are available to treat symptoms of the disease, including medications for memory loss and treatments for behavioral and sleep changes associated with this condition. None of these are addressed in the news release.
The news release provided a thorough description of the probiotic milk intervention, but did not mention the fact that it was manufactured (in Iran) specifically for this study and is not available for purchase. A brief discussion of what it would take to get such a product on the market — in addition to its cost — would be beneficial.
This release highlights the novelty of the intervention, stating that this was the first time that human research has shown that probiotic bacteria can improve cognitive function. However, the release took a cautious approach to interpretation of the results, highlighting that the study was an early clinical trial and that researchers plan to examine the information in more detail in future studies. The release also included a comment from an independent researcher who is working in the same area of gut microbiome and brain function.
In line with its interpretation of the study’s novelty, the news release does not engage in sensational language nor does it overstep the conclusions drawn from the journal article. The release highlighted that, “Future research, on more patients and over longer time-scales, is necessary to test if the beneficial effects of probiotics become stronger after longer treatment.” Quotes were included from the researchers that showcased their optimistic yet conservative viewpoints on what the results may indicate and how they move forward to additional research on this topic.
However, a comment on the general usefulness of probiotics may have been a bit biased toward the supplement. The statement, “Probiotics are known to give partial protection against certain infectious diarrheas, irritable bowel syndrome, inflammatory bowel disease, eczema, allergies…”, etc., portrays probiotics as a recognized beneficial treatment or prevention strategy for these conditions, when that is certainly not the case. Much of the probiotic research done on individuals with these conditions has shown mixed results – and even then, has only shown benefit in specific populations. This is not strong enough evidence to describe them as known to be beneficial.