Here you can find more information on the SAAND study, including the background to the study, the main findings and what they mean in the context of ADHD and autism.

Background and Aims

Attention deficit/hyperactivity disorder (ADHD) and autism are common neurodevelopmental conditions with significant impact on the child, family and wider social systems. While inattention and hyperactivity/impulsivity are core features of ADHD, autism is characterised by social communication and interaction difficulties, restricted and repetitive behaviours, interests, or activities. Atypical regulation of autonomic arousal, i.e., the physiological processes which support paying attention to and processing information in the world around us, has been proposed to explain altered cognitive and global functioning in these conditions.

The system responsible for regulating autonomic arousal is the Autonomic Nervous System (ANS). When we need to focus on something boring or mentally difficult, the ANS tries to increase alertness so that we can complete a certain task. At other times, when we need to rest, the ANS reduces our alertness to the outside world so that we can ‘switch off’. Of course, this doesn’t always work! Sometimes we cannot focus our attention when we need to, and sometimes we can’t switch off. We think these difficulties might be greater in people with ADHD and autism.

Specifically, people with ADHD are likely to suffer from reduced activation of the ANS (hypo-arousal) and this might make it harder for them to maintain their attention when tasks are long or boring. On the other side, autistic people seem to show a more mixed profile with both hypo-arousal and hyper-arousal, i.e., increased stress and difficulties in reducing alertness to optimal levels. However, this might depend on the context, for example, if it is a boring and non-stimulating environment or if the situation is overwhelming in terms of sensory stimuli such as lights, colours or sounds, or more mentally demanding.

In the SAAND study, we wanted to find out whether autonomic arousal affects the ability to control attention in ADHD and autism.

Experimental paradigms and activities

Between September 2017 and May 2019, about 130 children and young people were invited to the Institute of Mental Health to complete a set of attention tests while electroencephalography (EEG) and eye-tracking data were recorded as well as heart rate. The attention tests comprised a 3-minute resting-state period, a ‘passive’ auditory oddball task (where auditory tones were delivered through speakers while participants watched a silent movie) and an ‘active’ response conflict task (where participants were required to make a directional left or right response to a target stimulus presented in left or right visual field, following a directionally congruent or incongruent cue stimulus).

Main findings

Children with ADHD and autism had different autonomic arousal profiles. Children with ADHD were characterised by hypo-arousal during resting-state and the passive auditory attention task, while autistic children showed hyper-arousal during the active task. In children with a double diagnosis, we observed hypo-arousal during the resting-state and the passive task (like those with ADHD-only), and hyper-arousal during the active task (like those with autism-only).

Interestingly, among autistic children (with or without co-occurring ADHD), increased autonomic arousal was associated with higher parent-reported social and communication difficulties, increased anxiety and reduced global functioning. We also observed atypical electrophysiological markers of response conflict/inhibitory control in children with ADHD, but only during more mentally demanding trials.

Moreover, dysregulated autonomic arousal affected task performance and behaviour. During the active task, children without ADHD (but not those with ADHD) displayed a cardiac acceleration after the onset of task-relevant stimuli, probably to facilitate response preparation. Among children with ADHD, those who displayed smaller or no heart rate acceleration after these visual stimuli, were slower to respond.

Implications and future directions

The SAAND study has been one of the first to investigate the effects of ADHD and co-occurring autism on autonomic arousal and attention, providing some new knowledge about these conditions. Our findings suggest that children with ADHD may be more inattentive in less engaging situations or when attention should be maintained for long periods of time, while autistic children may experience excessive autonomic arousal and reactivity in more demanding situations (for example, while performing cognitive tasks under time pressure or when sensory stimulation is too high).

People with co-occurring ADHD & autism might find it difficult to maintain attention in different situations, and together experience excessive distractibility and hyper-reactivity to sensory stimulation, struggling to focus on the ongoing task and displaying general difficulties in carrying out everyday life activities.

Allowing periods of movement/physical activity and rest, teaching self-regulation strategies to up- or down-regulate arousal (including breathing exercises or mindfulness), and using engaging stimuli, positive rewards and reinforcers, might improve arousal regulation and attention in autistic children and children with ADHD, both at home and at school.

It would be interesting to implement wearable devices, such as smartwatches or Fitbit™ that people with ADHD can use at school or in their workplace. This could provide clinicians with objective measures of autonomic arousal in both life- and laboratory-settings, which could be used to drive the choice of medication and potentially predict the outcome of medical treatment.

Dissemination

Findings of the SAAND study have been presented to different national and international conferences, including the World Congress of ADHD (2021), EUNETHYDIS Conferences on ADHD (2018-2020), Neurodevelopmental Disorders Annual Seminars (2017-2019),  Centre for ADHD and Neurodevelopmental Disorders Across the Lifespan (CANDAL) conference (2019), British Psychological Association Cognitive Psychology Section & Developmental Psychology Section Joint Conference (2019). We are also preparing a brief online blog for the Association for Child and Adolescent Mental Health (ACAMH), which will be shared with clinicians and healthcare professionals. In this blog, we will share the main findings of the study by focusing on the potential clinical implications.

A full list of articles published by the SAAND research team can be found here.

Acknowledgments and funding

We would like to thank the families and children who have been involved in the SAAND study and those who are involved in research, without whose contribution none of our projects as researchers and academics would be feasible.

The SAAND study was funded by:

• The University of Nottingham
• The Waterloo Foundation
• The Baily Thomas Charitable Fund
• The National Institute for Health Research Nottingham Biomedical Research Centre Mental Health & Technology Theme

For more information about the study, you can get in touch with the Principal Investigator, Dr Maddie Groom (This email address is being protected from spambots. You need JavaScript enabled to view it.).