Saliva cortisol, melatonin levels and circadian rhythm alterations in Chinese primary school children with dyslexia

Abstract

Cortisol is the main end product of hypothalamic-pituitary-adrenal gland (HPA axis), and melatonin (MT) has a regulating effect on HPA axis, and both are closely related to individual behavior and cognitive function. We aimed to evaluate cortisol and MT roles on children dyslexia in this study. A total of 72 dyslexic children and 72 controls were recruited in this study. Saliva samples were collected in the morning, afternoon, and night, respectively. The levels of saliva cortisol and MT were measured by enzyme-linked immunosorbent assay method. Differences of cortisol and MT levels between dyslexic and normal children were compared, and the variation trend was also analyzed by dynamic monitoring in 3 time points. The levels of salivary cortisol and MT in children with dyslexia were all lower than those in normal children whether in the morning (7:30-8:30 am ), at afternoon (15:30-16:30 pm ) or at night (21:30-22:30 pm ) (all P < .001). Compared with normal children, the circadian rhythm variations of salivary cortisol and MT in dyslexic children disappeared and became disordered. The salivary cortisol and MT levels in children with dyslexia were declined throughout the day; and the circadian rhythm was disordered or disappeared. The results suggest that cortisol and MT levels and their circadian rhythm may affect children dyslexia, but the mechanisms need further exploration.

Cortisol on Circadian Rhythm and Its Effect on Cardiovascular System

“…The physiological function of the HPA axis is important to preserve homeostasis, adapt to environmental surroundings, and regulate human behavior, emotion, and cognitive functions. The main end product of the HPA axis is cortisol, a glucocorticoid hormone that is highly associated with circadian rhythms [ 41 ]. Cortisol is considered the major glucocorticoid in both humans and nonhuman primates, and it is produced in response to a variety of stressors [ 42 ].…”

“…Cortisol rhythmicity is crucial for the normal function of the HPA axis; it is not only influenced by external factors such as sleep and season but also by stress factors such as mental, psychological, or physical status [ 41 ]. Stress factors, especially during the “fight or flight” response, will impact plasma cortisol levels [ 57 ].…”

“…Stress factors, especially during the “fight or flight” response, will impact plasma cortisol levels [ 57 ]. Irregular cortisol as a result of HPA axis impairments may, in turn, inordinate circadian rhythm and pose health risks on human emotion and behavior and physical and cognitive capabilities [ 41 ]. Reduced levels of cortisol as a result of adrenal insufficiency and ACTH deficiency, such as in congenital adrenal hyperplasia conditions, may consequently result in Addison’s disease [ 46 ] and can propagate other neurological disorders such as attention deficit hyperactivity disorder (ADHD) [ 58 , 59 , 60 , 61 ], dyslexia [ 62 ], and autism [ 63 ].…”

Personality, Behavior Characteristics, and Life Quality Impact of Children with Dyslexia

“…The control group was typical development children of the same age and grade from the same four primary schools. The recruited children have been finally diagnosed as dyslexia according to Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DMS-5) and confirmed by literacy tests by experts from the Mental Health Center of Shantou University Medical College [20]. Our research group compiled the literacy test tool (40-50 min), named Assessment of Chinese Literacy for Primary School Students (ACLPSS), in previous screening survey.…”

An Evolutionary Perspective of Dyslexia, Stress, and Brain Network Homeostasis

“…Recent research in dyslexia is consistent with this hypothesis. Dyslexia has been associated with the expression of stress-related genes ( Zakopoulou et al, 2019 ) and with dysregulation of the HPA stress system ( Espin et al, 2019 ; Huang et al, 2020 ). Thus, the Evo-Devo account of stress, combined with these preliminary studies, support the possibility that prenatal and early childhood adversity may be a dyslexia risk factor, and the natural outcome of an evolutionarily conserved adaptive response to stress.…”