Exploring objective measures of overactivity in children with rare genetic syndromes

Abstract

Abstract Background Overactivity is prevalent in several neurodevelopmental conditions, including Smith-Magenis syndrome, Angelman syndrome, and tuberous sclerosis complex, although has been predominantly measured using questionnaire techniques. Threats to the precision and validity of questionnaire data undermine existing understanding of this behaviour. Previous research indicates objective measures, namely actigraphy, can effectively differentiate non-overactive children from those with attention-deficit hyperactivity disorder. This study is the first to examine the sensitivity of actigraphy to overactivity across rare genetic syndromes associated with intellectual disability, through comparisons with typically-developing peers and questionnaire overactivity estimates. Methods A secondary analysis of actigraphy data and overactivity estimates from The Activity Questionnaire (TAQ) was conducted for children aged 4-15 years with Smith-Magenis syndrome (N=20), Angelman syndrome (N=26), tuberous sclerosis complex (N=16), and typically-developing children (N=61). Actigraphy data were summarized using the M10 non-parametric circadian rhythm variable, and 24-hour activity profiles were modelled via functional linear modelling. Associations between actigraphy data and TAQ overactivity estimates were explored, alongside differences in actigraphy-defined activity between syndrome and typically-developing groups, and within-syndrome high and low TAQ overactivity groups. Results M10 and TAQ overactivity scores were positively correlated for children with Angelman syndrome, and near-significantly correlated for children with Smith-Magenis syndrome. M10 did not differ between the syndrome and typically-developing groups. Higher early morning activity and lower evening activity was observed across all syndrome groups relative to typically-developing peers. High and low TAQ group comparisons revealed syndrome-specific profiles of overactivity, persisting throughout the day in Angelman syndrome, occurring during the early morning and early afternoon in Smith-Magenis syndrome, and manifesting briefly in the evening in tuberous sclerosis complex. Discussion These findings support the sensitivity of actigraphy to overactivity in children with rare genetic syndromes, and provide syndrome-specific temporal descriptions of overactivity. The findings advance existing descriptions of overactivity, provided by existing questionnaire techniques, in children with rare genetic syndromes and have implications for the measurement of overactivity. Future studies should examine the impact of syndrome-related characteristics on actigraphy-defined activity, and actigraphy and questionnaire estimates of overactivity.