In a randomized double-blind trial, scientists show for the first time that dietary supplementation with daily dose of probiotic bacteria over a period of just 12 weeks is sufficient to yield a small but significant improvement in the cognitive performance of Alzheimer’s patients.

For the first time, scientists have shown that probiotics — beneficial live bacteria and yeasts taken as dietary supplements — can improve cognitive function in humans. In a new clinical trial, scientists show that a daily dose of probiotic Lactobacillus and Bifidobacterium bacteria taken over a period of just 12 weeks is enough to yield a moderate but significant improvement in the score of elderly Alzheimer’s patients on the Mini-Mental State Examination (MMSE) scale, a standard measure of cognitive impairment.

Probiotics are known to give partial protection against certain infectious diarrheas, irritable bowel syndrome, inflammatory bowel disease, eczema, allergies, colds, tooth decay, and periodontal disease. But scientists have long hypothesized that probiotics might also boost cognition, as there is continuous two-way communication between the intestinal microflora, the gastrointestinal tract, and the brain through the nervous system, the immune system, and hormones (along the so-called “microbiota-gut-brain axis”). In mice, probiotics have indeed been shown to improve learning and memory, and reduce anxiety and depression- and OCD-like symptoms. But prior to the present study there was very limited evidence of any cognitive benefits in humans.

Here, the researchers, from Kashan University of Medical Sciences, Kashan, and Islamic Azad University, Tehran, Iran, present results from a randomized, double-blind, controlled clinical trial on a total of 52 women and men with Alzheimer’s between 60 and 95 years of age. Half of the patients daily received 200 ml milk enriched with four probiotic bacteria Lactobacillus acidophilus, L. casei, L. fermentum, and Bifidobacterium bifidum (approximately 400 billion bacteria per species), while the other half received untreated milk.

At the beginning and the end of the 12-week experimental period, the scientists took blood samples for biochemical analyses and tested the cognitive function of the subjects with the MMSE questionnaire, which includes tasks like giving the current date, counting backwards from 100 by sevens, naming objects, repeating a phrase, and copying a picture.

Over the course of the study, 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). Even though this increase is moderate, and all patients remained severely cognitively impaired, these results are important because they are the first to show that probiotics can improve human cognition. 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.

“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,” says Professor Mahmoud Salami from Kashan University, the senior author of the study.

Treatment with probiotics also resulted in lower levels of triglycerides, Very Low Density Lipoprotein (VLDL), high-sensitivity C-Reactive Protein (hs-CRP) in the blood of the Alzheimer patients, and likewise a reduction in two common measures (called “Homeostatic Model Assessment”, HOMA-IR and HOMA-B) of insulin resistance and the activity of the insulin-producing cells in the pancreas.

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

Walter Lukiw, Professor of Neurology, Neuroscience and Ophthalmology and Bollinger Professor of Alzheimer’s disease at Louisiana State University, who reviewed the study but was not involved in the research, said: “This early study is interesting and important because it provides evidence for gastrointestinal (GI) tract microbiome components playing a role in neurological function, and indicates that probiotics can in principle improve human cognition. This is in line with some of our recent studies which indicate that the GI 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 barriersbecome 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.”

The study is published in the open-access journal Frontiers in Aging Neuroscience.

Link to EurekAlert!: https://www.eurekalert.org/emb_releases/2016-11/f-pic110116.php

Link to study: http://journal.frontiersin.org/article/10.3389/fnagi.2016.00256/full

Moms respond more strongly to moral faults by infants than to other type of misbehavior, regardless of the potential harm, shows a new study.

Research in the journal Frontiers in Psychology shows that mothers typically respond more strongly to any “moral” faults by their infants – that is, which risk hurting other people or pets – than to any other type of misbehavior. Even misbehavior that puts the infant herself, but no-one else, at potentially risk, for example running down the stairs, is generally disciplined less strongly by moms than moral wrongdoing. Conversely, infants are more ready to obey, and less likely to protest against, their mother’s prohibitions on moral faults than prohibitions on other types of misbehavior. These results indicate that mothers tend to treat moral wrongdoing as a special, more serious type of misbehavior, regardless of the potential harm.

“Mothers were more insistent on the moral prohibition against harming others than prohibitions against doing something dangerous or creating mess or inconvenience, as shown by their greater use of physical interventions and direct commands in response to moral transgressions,” says the author Audun Dahl, Assistant Professor at the Department of Psychology at the University of California at Santa Cruz.

Dahl and coworkers observed interactions between 26 mothers, their 14-month infant girls or boys, and an older sibling below 8 years of age during 2.5-hour-long home visits, and repeated the visits 5 and 10 months later. Mothers were told to behave naturally, as the purpose was to study the everyday experience of infants. The observers scored each instance of infant naughty behavior, distinguishing between moral, “prudential” (dangerous to the infant herself, but to no-one else) and “pragmatic” faults (i.e. creating mess or inconvenience, but not harmful to the infant or anyone else). They also scored the mother’s response to each behavior, for example physical restraint; commands; distracting the infant from the unwanted behavior; softening, such as saying “I know you want to play with my phone” to acknowledge the infant’s wish, comforting him or her, or using of terms of endearment; compromising on an earlier prohibition; or explaining why the infant’s behavior was wrong. Other variables were the infant’s response, for example compliance with their mother’s instructions, protest, or expressing negative emotions, and the seriousness of the actual or potential consequences of the behavior.

The results show that mothers consistently respond with high-intensity interventions such as physical restraint and commands, and not with gentler interventions, whenever their infants showed moral misbehavior. In contrast, mothers were more likely respond to pragmatic or prudential transgressions with low-intensity interventions, especially distraction, softening or compromising. Furthermore, infants were significantly more likely to comply immediately with their mother’s commands when their original transgression had been moral, and less likely to protest verbally. Importantly, the greater insistence of mothers on moral rules couldn’t be attributed to moral transgressions having more severe potential consequences, since the observed prudential misbehaviors was on average more harmful – for example, putting the infant at risk of falling or choking.

Dahl concludes that mothers tend to treat the moral imperative to avoid harm to others as fundamentally different — more important to communicate and less open to negotiation — from prudential and pragmatic rules.

“Through their more insistent interventions on moral misbehavior, mothers appear to help their children make this distinction as well,” says Dahl. “Still, how parents react to misbehaviors is only one of many factors in early moral development. So an important question for future research is how precisely young children make use of their mother’s reactions, along with other experiences, to gradually develop their own notions of right and wrong,” says Dahl.

Link to study: http://journal.frontiersin.org/article/10.3389/fpsyg.2016.01448/full

EurekAlert! PR: https://www.eurekalert.org/pub_releases/2016-10/f-hy100616.php

The preference of Heliconius butterflies for certain leaf shapes is innate, but can be reversed through learning. These results support a decades-old theory for explaining the evolution of the exceptional diversity of leaf shapes in passionflowers.

The tropical butterfly Heliconius erato distinguishes between shapes, and uses them as a cue for choosing the plants on which to feed and lay eggs, shows new research by scientists from the University of Cambridge and the Smithsonian Tropical Research Institute. The butterfly has an innate preference for passionflowers with particular leaf shapes, but can learn to overcome this preference in favor of other shapes, especially those that are the most abundant in the local flora. These preferences can promote the evolution of plant biodiversity.

Heliconius erato, the red passionflower butterfly, is a large (5 to 8 cm wingspan), white-red-black butterfly that occurs throughout Central America and tropical South America. Females lay their eggs on passionflowers (Passiflora), a genus of tropical vines with extreme variation in leaf shape, both between and within species. For example, related species can have triangular, elongated, elliptic, lobed, or spear-shaped leaves, while even on the same plant leaf shape may vary between young and old, or sun-exposed or overshadowed leaves. Once caterpillars hatch from the eggs, they start feeding on the leaves and shoots of the host plant, often causing considerable damage.

“Here, we show for the first time that female Heliconius erato use shape as a cue for selecting the passionflowers on which they feed and lay eggs,” says Denise Dell’Aglio, a doctoral student at the Department of Zoology of the University of Cambridge.

“These findings have implications for ecological theory, because they support a decades-old hypothesis that the butterflies could drive so-called ‘negative frequency dependent selection’ on the leaf shape of passionflowers, that is, natural selection where the rarest forms always have a competitive advantage. This could explain the extraordinary diversity of leaf shapes found in passionflowers.”

According to this hypothesis, first formulated in 1975 but never tested until now, female Heliconius develop a learned preference – a “search image” – for passionflowers with common leaf shapes, and lay their eggs exclusively on these plants, which then suffer damage from the caterpillars. This would drive a cycle in which passionflowers with rare leaf shapes tend to do better and have more offspring – until over the next generations they become more common in turn, and lose their competitive advantage.

Here, Dell’Aglio and colleagues use artificial flowers and leaves, made out of foam sheet, to test the preferences of Heliconius erato females for particular shapes. They first show that the butterflies have an innate preference for feeding on star-like flowers with three and five petals over flowers with simpler shapes. But they can quickly learn to reverse this preference if the simpler flowers reliably contain a food reward, show the researchers. In a second experiment, Dell’Aglio et al. show that Heliconius erato prefer to lay eggs on leaves with a familiar shape, and tend to avoid laying on leaves with a shape that they have not previously encountered. These results indicate that the butterflies develop search images for familiar leaf and flower shapes, in support of the theory.

“Negative frequency dependence, where rare forms have an advantage, is thought to be a common process that promotes diversity in tropical plants. It is therefore exciting to think about how commonly this may be driven by behavioral flexibility in predators. Perhaps other insects might learn chemical signatures, textures or other physical cues and similarly promote diversity in their host plants,” says Chris Jiggins, Professor of Evolutionary Biology at the University of Cambridge, and one of the coauthors on the new study.

EurekAlert! PR: http://www.eurekalert.org/pub_releases/2016-07/f-bud072116.php

Study: http://journal.frontiersin.org/article/10.3389/fevo.2016.00081/full