December 5, 2013

expert reaction to gut bacteria and autism-related behaviour

Cell published a paper linking autism-like neurodevelopmental symptoms in mice to changes in the animals’ gut bacteria.

Dr Cathy Fernandes, Lecturer in Preclinical Models of Neurodevelopmental Disorders, Institute of Psychiatry, King’s College London, said:

“The first thing to say is that this research is in mice and the second is that only a subset of people with autism spectrum disorder (ASD) have gastrointestinal (GI) problems, so any implications of this research extrapolated to humans would not apply to everyone.

“These findings are interesting but the interpretation is speculative. The paper shows a behavioural response to GI tract disturbance. The authors have made a big leap to say that this equates to ASD because there is evidence for GI tract disturbance in ASD. However, the association could be correlative/coincidence and not necessarily causative.

“A likely (and simple) explanation for their data is that the mice were unwell due to GI tract disturbance which resulted in a non-specific/secondary behavioural response. Another important point is that there is no specificity to their findings, something the authors do acknowledge in the discussion. One of the main problems with animal models is that we can only model simple aspects of disorders. Therefore it is hard to make a specific claim about a deficit like anxiety or social interaction as these are features of several psychiatric disorders/neurodevelopmental disorders. For example, you could easily rewrite the manuscript replacing ASD with schizophrenia.”

Dr Simon Wallace, Research Director, Autistica, said:

“It’s important to stress that this study does not provide evidence of a new treatment for autism. The paper reports that mice born to mothers who have had an infection during pregnancy show both an increase in gut problems and behavioural changes related to autism. The gut problems these mice show were reportedly treated with a probiotic.

“Here this has been modelled in mice, and there is a big scientific leap to consider this as a treatment to help people with autism. The researchers suggest that the behaviour in the mouse may apply to other neurological conditions such as schizophrenia as well as autism, so there remains a question over its specific relevance to autism.

“Even if this was extended to human trials, it would only be relevant to a subset of people with autism – those with gastro-intestinal problems. We look forward to the follow up studies, and applaud all commitment to research to support people with autism, but we strongly encourage families to wait for real evidence before trying any medications or supplements.”

Richard Mills, Research Director, Research Autism, said:

“The term autism is used to describe a constellation of neurodevelopmental disorders, which vary considerably in their presentation and severity.  The causes of the different forms of autism are not yet understood and there is currently no agreed biological, psychological or genetic cause. Diagnosis of autism is still made on the basis of observed behaviour.

“Research using mouse models is important in developing our understanding of basic neurology and physiology but it is highly premature and unwise to come to any conclusions on the basis of such research or to apply any findings to humans. The varied nature of autism means that it is impossible for any one treatment to be effective and it is important to take an informed,  holistic and personalised view based on assessment of each individual’s needs. Gastrointestinal problems in autism are more common than in the general population but are not present in every autistic person. These problems are sometimes linked to sensory processing disorders and where they do occur they are often severe.  It is therefore important that they are properly evaluated and treated by a specialist physician with support from an Occupational Therapist, and not subjected to experimental treatment with probiotics, special diets or anything else.

Dr Michael Fitzpatrick, GP and autism expert, said:

“Contrary to the impression created by the concluding sentences in the summary and discussion sections, this study does not identify a potential probiotic therapy for people with autism and gastrointestinal problems. It suggests that there may be a link between gastrointestinal pathology and behavioural abnormality, possibly mediated by immune dysfunction, in mice, which – if confirmed – may provide some clues worth following up in humans.

“The study did not investigate ‘microbe-mediated therapies’ in humans and the claim that such treatments ‘may be safe and effective’ is simply appended as a claim not only to clinical relevance, but to therapeutic benefit, before even the most preliminary of trials.”

‘Microbiota Modulate Behavioral and Physiological Abnormalities Associated with Neurodevelopmental Disorders’ by Hsiao et al. published in Cell on Thursday 5th December.