Muller, R.-A. | bioRxiv Science

bioRxiv2024

Decreased BOLD signal variability in middle-aged and older adults on the Autism Spectrum

PurposeAutism spectrum disorder (ASD) is a lifelong neurodevelopmental disorder. Preliminary evidence suggests an increased risk for accelerated or early-onset cognitive and neurological decline in ASD. While it is well established that brain development in children, adolescents and young adults with ASD diverges from neurotypical (NT) peers, it is unknown how brain function is impacted in older adults with ASD. Understanding age-related changes of brain function in ASD is crucial to establish best practices for cognitive and health screenings in adults with ASD and develop interventions that might reduce the risk of accelerated decline. Decreases in blood-oxygenation-level-dependent (BOLD) signal variability (BSV) in typical aging have been shown across multiple studies, likely reflecting declining Gamma-Aminobutyric Acid (GABA) activity, and is associated with poorer cognitive performance. We hypothesized that adults with ASD would show reduced BSV compared to the NT group, with steeper negative age associations in the ASD than NT group. MethodsThe study assessed BSV in a cohort of adults (40-70 years), 28 with ASD and 39 age-matched NT. General linear models tested for main effects of diagnostic group (ASD, NT), age and group-by-age interactions (controlling for RMSD). LimitationsOur cross-sectional data and small sample size highlight the need for longitudinal analyses in larger cohorts, alongside exploring links to cognitive function. Additionally, psychotropic medications used by our cohort of adults on the autism spectrum may have affected BSV. ResultsSignificant group-by-age interactions were observed for the right insular, left temporal occipital fusiform, right frontal orbital and right inferior lateral occipital cortex, with BSV showing strong negative associations with age in the ASD but not NT group. ConclusionThese findings suggest that BSV decreases may occur earlier in adults on the autism spectrum compared to their neurotypical peers, possibly indicating accelerated aging. However, given limited prior research, additional longitudinal analyses will be necessary to determine if the results presented truly reflect accelerated aging or arise from lifelong persistent differences in brain function.

neuroscience↗

bioRxiv2021

Sleep problems in preschoolers with autism spectrum disorders are associated with sensory sensitivities and thalamocortical overconnectivity

Projections between the thalamus and sensory cortices are established early in development and play an important role in sleep regulation as well as in relaying sensory information to cortex. Atypical thalamocortical functional connectivity frequently observed in children with autism spectrum disorders (ASD) might therefore be linked to sensory and sleep problems common in ASD. Here we investigated the relationship between auditory-thalamic functional connectivity measured during natural sleep fMRI, sleep problems, and sound sensitivities in 70 toddlers and preschoolers (1.5 to 5-year-olds) with ASD compared to a matched group of 46 typically developing (TD) children. In children with ASD, sleep problems and sensory sensitivities were positively correlated, and increased sleep latency was associated with overconnectivity between the thalamus and auditory cortex in a subsample with high quality MRI data (n=29). Additionally, auditory cortex BOLD signal amplitude was elevated in children with ASD, potentially reflecting reduced sensory gating or a lack of auditory habituation during natural sleep. These findings indicate that atypical thalamocortical functional connectivity can be detected early in development and may play a crucial role in sleep problems and sensory sensitivities in ASD.

neuroscience↗