Sweating an Early Warning Sign of Behavioral Outbursts in Autism?

Deborah Brauser

November 22, 2019

In patients with severe autism, sweat sensors signaling rising electrodermal activity (EDA) may forewarn clinicians and others of a behavioral outburst and provide an early opportunity to stop such incidents before they start.

In a small feasibility study involving eight boys with severe ASD, ankle and wrist monitors recorded an increased level of sweat, signaling a rise in EDA, 60% of the time before a problem behavior, such as self-harm or aggression, occurred.

Dr Bradley Ferguson

"A spike in [EDA] is telling us that the individual's body is reacting physiologically to something that is stressful," lead author Bradley J. Ferguson, MD, Departments of Health Psychology and Radiology at the University of Missouri (MU) School of Medicine, Columbia, said in a press release.

Notification of increasing stress may give caregivers a chance to intervene and deescalate a situation, added Ferguson, who is also at the Thompson Center for Autism and Neurodevelopmental Disorders at MU.

"If we see stress levels starting to rise, that would be an indicator that the individual needs some type of intervention ― whether it be removing them from the situation or giving them a break or something else," he told Medscape Medical News.

Ferguson noted that although this was a small study, the results will be beneficial for future research on data collecting through sensor monitoring and for other feasibility studies on ways to use such data.

The findings were published online September 11 in Frontiers in Psychiatry.

Aggression, Self-injury, Irritability

"Research has demonstrated that many individuals with ASD engage in aggression and other problem behaviors such as self-injurious behavior and irritability," the investigators write.

In addition, those with limited communication and social engagement skills are at an even higher risk for the development of such behaviors, they add.

Because stress can often lead to problems in this patient population, researchers have begun to investigate ways of measuring EDA in order to assess changes in an individual's internal state of stress.

"Increases in EDA indicate activation of the sympathetic nervous system (the 'fight or flight' response of the autonomic nervous system)," the researchers write.

"Activation of the sympathetic nervous system results in secretion of sweat, which conducts electricity, from eccrine sweat glands throughout the body," they add.

"Oftentimes these individuals who are severely affected by autism can't verbally tell us when they're getting stressed out. Often, their way of communicating to us that they are stressed is problem behaviors," Ferguson said.

In the current study, the investigators sought to evaluate the feasibility of collecting EDA data from adolescents with severe ASD.

Noninvasive Technology

Eight boys (mean age, 15.9 years; six white and two Hispanic) who were residents at the Center for Discovery were included in the study.

All participants had scores on the Autism Spectrum Rating Scales that fell in the "elevated" (scores, 65 – 69) or "very elevated" (scores, 70 – 85) categories.

Other measures that were used included the Stanford-Binet Intelligence Scales or the Comprehensive Test of Nonverbal Intelligence, the Adaptive Behavior Assessment System General Adaptive Composite score, and the Vineland Adaptive Behavior Scales Adaptive Behavior Composite score.

The most common problem behavior was a self-injurious action, followed by aggression, inappropriate social behavior, and noncompliance.

"These individuals at the Center go to school during the day and they have a lot of quite significant problem behaviors, ranging from hitting and biting themselves to bothering their classmates or getting out of their seats and running around the room," Ferguson reported.

EDA data were collected while participants were in "a naturalistic" classroom setting in the Center for Discovery's lab school, which uses hidden video cameras and microphones to collect behavioral information.

Q-Sensor pod wristband.

If tolerated, Q-Sensor pod wristbands (Affective Inc) with dry electrodes were placed on wrists in order to collect data on EDA patterns. If a participant could not tolerate wearing a sensor on the wrist, the device was applied instead to the ankle.

"These sensors are very noninvasive. You're able to strap them on like a watch with a Velcro band, and they're wireless. You just press a button and it turns on and records for a few hours at a time," Ferguson said

Only the first occurrence of a problem behavior per session was analyzed.

A Window of Opportunity

Results showed that 60% of the episodes of problem behavior were linked to an "anticipatory rise in EDA" beforehand.

"This has important implications for efforts to utilize psychophysiological markers as a predictor of problem behaviors," the investigators write.

"However, individuals varied in the frequency with which an anticipatory rise in EDA was observed," they add.

Interestingly, the greatest incidence of increased EDA occurred in boys who had primarily displayed self-injurious behavior and general classroom disruption. On the other hand, the least incidence of an anticipatory rise in EDA occurred in those who primarily engaged in aggression.

Across all of the documented problem behaviors, EDA levels returned to median baseline values an average of 45% of the time after a problem behavior had occurred.

Again, the frequency with which these levels returned to baseline measurements varied among the students.

EDA responses among study participants differed. Some experienced a gradual increase leading up to the problem behavior, peaked during the incident, and then gradually decreased, whereas for others, patterns were variable.

When an anticipatory rise was found, EDA increased for an average of 10 minutes prior to the occurrence of a problem behavior, "providing a window of opportunity for intervention to occur," the investigators note.

Overall, "findings from this exploratory study suggest that examining the relationship between EDA and problem behaviors is feasible" in patients with severe ASD and in this type of setting, they add.

A Teachable Moment?

"This research highlights the individual variability...that must be considered, and may also have implications for individualized treatment approaches moving forward," coinvestigator Devid Beversdorf, MD, professor of radiology, neurology, and psychology at the MU College of Arts and Sciences, said in a release.

Ferguson said the sensors could be worn just when a child is mostly likely to engage in problem behaviors, such as while learning new things. However, "it would be ideal" if the sensors could eventually be worn all the time.

"We're already starting to see this technology emerge, not necessarily with [EDA] leads but with other physiological signals, like electrocardiogram heart-rate variability," he noted.

Ferguson reported that the next step is to develop a mobile app that would alert caregivers in real time to increases in a child's stress levels and that would offer caregivers an opportunity for early intervention.

"Maybe with the higher functioning individuals, you could actually use the stress data to give the individual some biofeedback, teach them about what's happening when their body is becoming stressed, and then teach them to ask for a break or some other intervention themselves," he said.

Ferguson also said the technology would be useful in other populations of persons who are prone to stress.

"I think that's the beauty of this technology, and I think it's where things are going naturally, with biosensors, etc. Then you can look at the data over time to be aware of stress patterns," he said.

The study was funded by the New York State Center of Excellence, the New York State Department of Health, the Office for People With Developmental Disabilities, and by money donated to the Center for Discovery. Ferguson has reported no relevant financial relationships.

Front Psychiatry. Published online September 11, 2019. Full text

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