The stress response of salivary alpha-amylase (sAA) has been suggested as an index for sympathetic nervous system activation. However, concurrent inhibition of the parasympathetic nervous system is discussed as a confounder due to suppression of saliva flow rate. Here we set out to test the influence of stress-induced changes in flow rate on sAA secretion. Twenty-six subjects underwent the Trier Social Stress Test and a control condition. Saliva was sampled by passive drooling or salivettes. Saliva flow rate, sAA levels and output, salivary cortisol, and heart rate variability were measured. Flow rate increased only when sampled by passive drooling. Stress-induced increases in amylase levels were correlated with increases of amylase output but not with flow rate. Results indicate that flow rate is not a confounder of stress-induced sAA activation and suggest that valid measurements of sAA can be obtained by salivettes without the need for assessment of flow rate.

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The aim of the present study was to assess the effects of daily stress perception on cognitive performance and morning basal salivary cortisol and alpha-amylase levels in healthy children aged 9-12. Participants were classified by whether they had low daily perceived stress (LPS, n = 27) or a high daily perceived stress (HPS, n = 26) using the Children Daily Stress Inventory (CDSI). Salivary cortisol and alpha-amylase were measured at awakening and 30 minutes later. Cognitive performance was assessed using the Cognitive Drug Research assessment system. The HPS group exhibited significantly poorer scores on speed of memory (p < .05) and continuity of attention (p < .05) relative to the LPS group. The HPS group also showed significantly lower morning cortisol levels at awakening and at +30 minutes measures in comparison with the LPS group (p < .05), and mean morning cortisol levels were negatively correlated with speed of memory (p < .05) in the 53 participants. No significant differences were observed between both groups in alpha-amylase levels. These findings suggest that daily perceived stress in children may impoverish cognitive performance via its modulating effects on the HPA axis activity. Keywords: children, self-perceived stress, salivary cortisol, salivary alpha-amylase, cognition El objetivo del presente estudio fue evaluar los efectos de la percepción de estrés diario sobre el rendimiento cognitivo y los niveles matutinos basales de cortisol y alfa-amilasa salivar en niños sanos de edades entre los 9 y los 12 años. Los participantes fueron clasificados en función de si su nivel de percepción de estrés diario era bajo (LPS, n = 27) o alto (HPS, n = 26), empleando el Children Daily Stress Inventory (CDSI). Se midió el cortisol y la alfa-amilasa salivar al despertar y 30 minutos más tarde. El rendimiento cognitivo se evaluó mediante el sistema de evaluación Cognitive Drug Research. El grupo HPS obtuvo puntuaciones significativamente más bajas en velocidad de memoria (p < .05) y continuidad de la atención (p < .05) con respecto al grupo LPS. El grupo HPS también mostró niveles significativamente más bajos de cortisol matutino al despertar y a los 30 minutos en comparación con el grupo LPS (p < .05), y sus niveles medios de cortisol matutino correlacionaron negativamente con la velocidad de la memoria (p < .05) en los 53 participantes. No se observaron diferencias significativas entre los grupos en los niveles de alfa-amilasa. Estos resultados sugieren que la percepción de estrés diario en niños puede disminuir su ejecución cognitiva a través de sus efectos moduladores en la actividad del eje HPA. Palabras

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