Psychophysiological Associations with Gastrointestinal Symptomatology in Autism Spectrum Disorder.
Bradley J Ferguson, Sarah Marler, Lily L Altstein and 14 others
PMID 27321113WHAT IT FOUND
More bowel symptoms in children and adolescents with autism were linked to a stronger resting heart measure reflecting relaxation and a weaker response to cold stress.
Upper gut symptoms showed no link. This is an association, not proof of cause.
Key findings
01pNN50, a heart-rate measure of parasympathetic activity, was significantly associated with lower gut symptom scores at baseline (P = 0.039, r = 0.20) and with the change in pNN50 after cold stress (P = 0.015, r = -0.24).
02Upper gut symptom scores showed no significant association with any psychophysiological variable.
03Lower gut symptom scores were significantly associated with higher irritability scores (P = 0.035, r = 0.20) and higher sleep-problem scores (P < 0.001, r = 0.37).
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
This was a correlational study, so it cannot show that autonomic differences caused gastrointestinal symptoms or that gastrointestinal symptoms caused autonomic differences. The sample was modest and the analyses were exploratory with uncorrected P-values. Some significant findings may be chance. Different measures analysed different numbers of participants: 10 were excluded from all autonomic analyses, 109 were analysed for vibrotactile heart-rate outcomes, 106 for cold-pressor heart-rate outcomes, and 84 for skin conductance outcomes. Few participants had upper gastrointestinal diagnoses, and many scored zero for upper gastrointestinal symptoms. This limits conclusions about upper gut symptoms. Gastrointestinal symptoms were measured by parent report or self-report. This may miss pain or discomfort in participants with limited speech. Participants taking medications that could affect gut movement, adrenergic, or serotonergic systems were removed in sensitivity analyses. This reduced the sample to 44 or 45 participants for some outcomes. Dietary restrictions, food preferences, and complementary alternative treatments were not assessed and could have influenced results. The enteric nervous system of the gut was not directly measured.
The easy way to misread this
Do not conclude that autism-related bowel symptoms cause the autonomic differences, or that calming the autonomic nervous system will relieve bowel symptoms. The study measured associations at one time point, and the authors state that causality cannot be assessed.