No, a yoghurt a day won’t help to beat Alzheimer’s

    14 November 2016

    Probiotics found in yoghurt and supplements could improve the cognitive skills and memory in people with Alzheimer’s disease, according to research at the Kashan University of Medical Sciences in Iran.

    The Daily Mail Online ran the headline: ‘Why having a probiotic yoghurt each day could help to alleviate symptoms of Alzheimer’s disease.’ (But see our analysis below.)

    During clinical trials involving 52 people between the ages of 60 and 95, those who drank a daily dose of lactobacillus and bifidobacterium bacteria for 12 weeks showed improvements in cognitive tests. The performance of those who were not given the probiotic supplements declined over the same period.

    At the beginning and end of the trial, the study authors tested the cognitive function of the test subjects using the MMSE scale, a standard measure of cognitive impairment.

    The average recorded score 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, in which it fell from 8.5 to 8.0. The researchers say this is the first evidence that probiotics can improve human cognition.

    The research, published in the journal Frontiers in Aging Neuroscience, suggests that changing gut bacteria through nutrition or supplements could help people suffering from neurodegenerative diseases.

    The study’s senior author, Mahmoud Salami, said: ‘In a previous study, we showed that probiotic treatment improves the impaired spatial learning and memory in diabetic rats, but this is the first time that probiotic supplementation has been shown to benefit cognition in cognitively impaired humans.

    ‘These findings indicate that change in the metabolic adjustments might be a mechanism by which probiotics affect Alzheimer’s and possibly other neurological disorders. We plan to look at these mechanisms in greater detail in our next study.’

    Instant analysis
    This randomised controlled trial found a statistically significant improvement in cognition among Alzheimer’s patients who took probiotics. At first sight this seems promising, but there are several major issues with this trial.

    There is no indication as to why 60 patients were selected to take part. In order to detect a meaningful statistical difference between the two groups, the study population needed to have been examined before the trial took place. There is no indication that this was done. As a result we have no idea from the paper as to whether an adequate number of patients was included in the first place.

    The mini-mental state exam (MMSE) used to assess improvement is far from the gold-standard cognitive test used to investigate Alzheimer’s disease. There are better, more comprehensive tests available and why this particular test was chosen is not explained.

    There are always quality control issues with commercially available probiotics, given that there is no set standard as there is with clinical drugs. This introduces an element of bias into the trial.

    While symptoms in the intervention arm appear to improve, albeit with a less than optimal cognitive testing method, no information was given regarding improvement in quality of life, which is important for Alzheimer’s patients.

    This trial is novel, but better and more rigorous research needs to be carried out before probiotics can be considered, even preliminarily, as another weapon in the fight against Alzheimer’s.
    Research score: 1/5