Autism spectrum disorders (ASD) include a classification of neurodevelopment disorders characterized by impairments in social interaction and communication, and restricted and repetitive behavior, generally exhibited before a child is three years old. The increasing rate of ASD is becoming an epidemic in this country and although it affects many parts of the brain, how this occurs is poorly understood. In addition to social and cognitive impairment, dysregulation of the LHPA axis has also been implicated in children with autism spectrum disorders.
The LHPA axis is a complex network of hormone-brain-behavior interactions that relies on communication between the central nervous system, the endocrine system, and the immune system, and is regulated with three interrelated processes including the maintenance of a diurnal rhythm, activation in response to stress or threat, and the restoration of basal activity via negative feedback mechanisms. It has been proposed that any or all of these processes could be affected in children with ASD. The study evaluated the activation and potential dysregulation of the LHPA axis, both diurnally and in response to different types of stress, by measuring salivary cortisol.
Cortisol is the primary glucocorticoid, the class of steroid hormones that bind to the glucocorticoid receptor at the cell level, in humans and monitoring cortisol is an often used, non-invasive method to measure changes in the LHPA axis. It was discovered that average diurnal cortisol was associated with parent-reported measures of stress and sensory sensitivity in the children with ASD, while measures of stress and parent-child stress were important explanatory variables for the neurotypical children. The cortisol stress response profiles were then characterized under two different induced stressors: a non-social mock MRI and a social playground interaction. During the mock MRI the children with ASD had higher levels of cortisol at all time points while the cortisol stress response profiles during the peer interaction were dependent upon age as well as diagnosis. Lastly the relationship between LHPA activation due to the stressors, diagnosis, and physical and behavioral characteristics were explored.
|Commitee:||Beckett, Laurel, Corbett, Blythe|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||DAI-B 71/11, Dissertation Abstracts International|
|Keywords:||Amygdala, Autism spectrum disorders, Cortisol, Limbic-hypothalamic-pituitary-adrenal axis, Stress responses|
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