Higher Salivary Cortisol Concentrations Research Articles

Diurnal patterns of salivary cytokines differentially correlate with greater fluctuations in cortisol and diet composition: A pilot study

Chronic stress and elevated cortisol are associated with adverse metabolic profiles and lifestyle patterns, systemic low-grade inflammation, and increased chronic disease risk; however, it is less clear how the degree of cortisol fluctuations impacts these parameters. Adult men and women (18-70y) were recruited to participate in a 5-day observational study, in which they underwent a baseline health and body composition assessment, completed 5-day diet, exercise, and stress records, and provided saliva samples in the morning, afternoon, and evening to measure fluctuations in cortisol, interleukin-1β (IL-1β), and IL-6. Degree of cortisol variability over the 5-day period (highest cortisol measure - lowest cortisol measure) was used to classify subjects into high (n = 9) and low (n = 9) cortisol fluctuation groups. Participants with greater fluctuations in salivary cortisol had higher salivary cortisol concentrations on average, which was attributed to higher maximal and morning cortisol. A greater proportion of individuals with higher cortisol flux worked in first responder/emergency professions, and exhibited minimal dietary pattern differences compared to those with low cortisol flux. While body fat percentage and mass positively correlated with minimum salivary cortisol measures, body composition and blood pressure did not differ between low vs. high salivary cortisol flux groups. Interestingly, we observed diurnal patterns of salivary IL-1β concentrations, with higher IL-1β in the morning, and greater afternoon IL-1β in the high cortisol flux group compared to the low cortisol flux group. Independent of cortisol flux, waking satiety and intake patterns of dietary nutrients and food groups/type differentially correlated with salivary cytokine concentrations in a time of day-dependent manner. Our findings suggest that greater fluctuations in cortisol are associated with distinct diurnal salivary cortisol and IL-1β concentrations but minimal lifestyle and dietary factors, whereas dietary patterns are strongly and differentially associated with salivary cytokine profiles.

Association between Salivary Cortisol and α-Amylase with the Psychological Profile of Patients with Oral Lichen Planus and Burning Mouth Syndrome: A Case-Control Study.

The aim of our study was to assess the relationship between the concentration/activity of salivary stress biomarkers (cortisol, α-amylase) and the psychological profile of patients with oral lichen planus (OLP) and primary burning mouth syndrome (BMS). A total of 160 subjects participated in this case-control study: 60 patients with OLP; 60 patients with primary BMS; and 40 control subjects. Unstimulated whole saliva (UWS) was collected between 9 and 10 a.m. Salivary biomarkers were analyzed by enzyme-linked immunosorbent assays (ELISAs). Psychological assessment was evaluated with the Depression, Anxiety, and Stress Scale (DASS-21). The patients with primary BMS had higher salivary cortisol concentrations and α-amylase activity (0.52 vs. 0.44 µg/dL; 160,531 vs. 145,804 U/L; one-way analysis of variance (ANOVA) with post hoc Scheffe test) compared with patients with OLP. The patients with primary BMS had statistically significant higher scores for depression, anxiety, and stress compared with patients with OLP and control subjects (p < 0.001, Kruskal-Wallis test). There was a strong positive correlation between anxiety and depression, stress and depression, and stress and anxiety in patients with OLP and BMS (p < 0.001 and p < 0.001, respectively; Spearman's correlation). There was a good positive correlation between symptom intensity (pain/burning) and psychological profile (depression, anxiety, stress) in patients with primary BMS (r = 0.373, p = 0.003; r = 0.515, p < 0.001; r = 0.365, p = 0.004, respectively; Spearman's correlation). This case-control study is the first to compare the psychoendocrinological profile of patients with two different oral diseases. The patients with BMS showed a higher concentration/activity of salivary stress biomarkers (cortisol, α-amylase) and a stronger association with mental disorders compared with patients with OLP. However, an interdisciplinary psychoneuroimmunological approach is equally important in both patient groups (OLP and BMS), regardless of whether mental disorders are the cause or the consequence.

Atypical maternal interaction is associated with elevated levels of hair cortisol in children.

The quality of maternal caregiving is an important factor in the healthy development of a child. One consequence of prolonged insensitive and atypical maternal interaction behavior (e.g., withdrawing from interactions with the child and role-reversal, i.e., the takeover of the parental role or parts of it by the child) in mother-child-dyads can cause alteration of the child's stress response system. Higher salivary cortisol concentrations were reported in infants and toddlers directly after negative interactions with their parents. However, no study to date has examined the association between atypical maternal interaction behavior and hair cortisol concentrations (HCC) in infants. Here, we studied the association of maternal interaction behavior with HCC of the child. Mother-child dyads (N = 112) participated in the longitudinal study My Childhood-Your Childhood. The AMBIANCE scale and its subscales were used to assess atypical maternal interaction behavior during the Strange Situation Procedure. Chronic stress levels in the child were assessed by HCC of 3 cm hair strands at the age of 12 months. Maternal educational level (operationalized in highest education level) served as a control variable. Robust multiple linear regression analyses revealed that role/boundary confusion was associated with HCC, i.e., the higher atypical interaction behavior of the mother the higher the HCC in the children. By measuring hair cortisol in this study, it is possible to determine the average long-term activity of the child's stress response system.Thus, atypical maternal interaction behavior could be a risk factor for persistent stress in children, contributing to a higher risk for negative health outcomes in later life. The results of this study highlight the importance of early intervention programs that focus on the relationship between mother and child.

Salivary parameters and periodontal inflammation in obstructive sleep apnoea patients

The aim of this cross-sectional study was to objectively assess the salivary flow rate and composition and periodontal inflammation in obstructive sleep apnoea (OSA) patients. The subjects, who underwent whole-night polysomnography or polygraphy, were referred for saliva sampling and periodontal examination. According to the severity of OSA based on the Apnoea Hypopnea Index (AHI) value, the subjects were classified into groups: no OSA (AHI < 5; N = 17), mild to moderate OSA (AHI 5–29.9; N = 109), and severe OSA (AHI > 30; N = 79). Salivary flow rate, pH, salivary electrolytes, and cortisol were measured from collected saliva samples. Periodontal examination included assessment of the number of teeth, dental plaque, bleeding on probing and periodontal measurements: gingival recession, probing pocket depth, clinical attachment level (CAL) and periodontal inflamed surface area (PISA) score. There were no significant differences in salivary flow rate, salivary pH, salivary electrolyte concentrations or electrolyte ratios among the groups classified according to the severity of OSA. However, subjects without OSA had higher salivary cortisol concentrations than OSA groups (p < 0.001). Increased plaque scores were associated with a higher AHI (r = 0.26; p = 0.003). According to the salivary flow rate, subjects with hyposalivation and reduced salivation had higher concentrations of salivary electrolytes and lower salivary pH than subjects with normal salivation. Subjects with hyposalivation had an increased Mg/PO4 ratio (p < 0.001) and a reduced Ca/Mg ratio (p < 0.001). Furthermore, subjects with severe OSA tended to have higher CALs and plaque volumes. In conclusion, under pathological conditions, such as OSA, multiple interactions might impact salivary flow and electrolyte composition. Complex interrelationships might affect the integrity of oral health, especially considering OSA severity, inflammation, concomitant diseases and medications.

Consequences of timing of organic enrichment provision on pig performance, health and stress resilience after weaning and regrouping

Most pigs in slatted systems are provided with enrichment meeting only minimum legal requirements. We aimed to explore the effects of a novel enrichment treatment consisting of daily provided fodder beet and jute bags for pigs in slatted systems, and investigate the timing of enrichment provision on performance, health and stress resilience. We used 280 weaners allocated into standard (S, meeting only legal requirements consisting of a plastic toy and softwood) or enriched (E) treatment (n = 14 groups/treatment). At regrouping during the grower to finisher transition, pigs were either kept in the same treatment (EE, SS) or switched from enriched to standard (ES) and vice versa (SE); each treatment was replicated on five groups. Pigs were weighted at the start and end of weaner, and finisher stage, and feed intake was recorded. Occurrence of scouring, respiratory problems, locomotor disorders, tail, ear, and body lesions were recorded twice a week. Ten males per treatment were sampled for saliva on days 1, 2 and 4, either postweaning or after the housing switch. Saliva samples were analysed for cortisol, alpha-amylase, haptoglobin (Hp), and adenosine deaminase. Additionally, these pigs were sampled for hair at the start and end of weaner, and end of finisher stage to analyse for hair cortisol and cortisone. We found that E weaners consumed less feed (P = 0.04), had better FCR (feed conversion ratio, P = 0.03) and less ear lesions for two weeks postweaning (P = 0.04), and tended to have lower occurrence of scouring (P = 0.07) and higher salivary cortisol concentrations (P = 0.09) than S weaners. Effects of enrichment treatment during weaner stage on performance were carried through to finisher stage, with EE and ES pigs having better FCR (P = 0.0009) and higher BW (P = 0.0001) compared to SS and SE pigs. E treatment during finisher stage decreased feed intake (P = 0.04) and tended to decrease Hp levels (P = 0.07). There was a significant interaction between enrichment treatments during weaner and finisher stages on finisher body lesions: EE finishers had less lesions than SS, ES, and SE finishers (P = 0.04). There were no other significant differences caused either by enrichment treatment during weaner/finisher stage or their interaction. We conclude that the novel enrichment applied at weaner stage had positive effects on ear lesions and performance, which were carried through to finisher stage. Body lesions were affected by its application during both stages, with finishers receiving the enrichment treatment throughout (EE) having reduced body lesions than the rest of the finishers.

Relationship between Stress and Bone Density, Using Salivary Cortisol, in Young Adult Women

Although cortisol is believed to increase the osteoclast activity and accentuate bone resorption, few studies are available on cortisol and bone density. This study uses salivary cortisol to investigate the relationship thereof with bone density. Furthermore, we investigated whether the salivary Ca concentration could be an effective biomarker in bone evaluations using salivary cortisol. This study targeted 188 healthy female college students (18 - 25 years old). Calcaneus bone density (Speed of Sound: SOS) was measured using an ultrasonic bone density measurement device. Food intake was calculated via a food intake frequency survey. The saliva of subjects was collected in order to measure the cortisol concentration using an enzyme immunoassay, while the salivary Ca concentration was measured using an atomic absorption spectrophotometer. The relationship between salivary cortisol and SOS was not significant, with a correlation coefficient of -0.13, indicating a negative correlation and leading to the observation that those with lower salivary cortisol levels tended to have higher SOS. The relationship between salivary cortisol and salivary Ca concentration was not significant, with a correlation coefficient of +0.15, indicating a positive correlation and leading to the observation that those with higher salivary cortisol concentrations tended to have higher salivary Ca concentrations. No significant correlation was observed in the relationship between salivary Ca concentration and SOS. Because the cortisol in saliva responds more sensitively to acute stress than to chronic stress, this may not have had obvious significance. Furthermore, the salivary Ca concentration indicated large fluctuations, depending on the daily external conditions, particularly in terms of food; therefore, it is believed that the presence or absence of dietary intake before the survey affected the results. The above results suggest that bone density may decrease, while salivary Ca concentration may increase when salivary cortisol concentration increases due to stress.

Effects of Enrichment Type, Presentation and Social Status on Enrichment Use and Behaviour of Sows with Electronic Sow Feeding

Simple SummaryMany North American pork producers are transitioning to group housing systems for gestating sows and are looking to provide animals with environmental enrichment. Because straw poses biosecurity and manure management concerns it is important to identify alternative enrichments which can benefit sow welfare. The effects of four enrichment treatments were studied: (1) Constant: constant provision of wood on chain; (2) Rotate: rotation of three enrichments (rope, straw and wood on chain); (3) Stimulus: rotation of three enrichments with an associative stimulus (bell or whistle); and (4) Control: no enrichment. Contacts with enrichment and time spent in different postures were measured using scan sampling for all sows. Skin lesions were scored and cortisol was measured in saliva samples in a subset of dominant and subordinate sows. Sows spent more time contacting enrichment in Rotate and Stimulus treatments than Constant, particularly when straw was provided. Subordinate sows spent more time near enrichments, and more time standing than dominant sows. Subordinate sows also received more skin lesions and had higher salivary cortisol concentrations than dominants. We conclude that enrichments are valued by sows, and that the right amount is needed to minimize competition over access. Additional work is needed on rotational schedules and determining appropriate levels of enrichment for sows.The goal of this study was to identify practical enrichments for sows in partially or fully slatted pen systems. Four treatments were applied: (1) Constant: constant provision of wood on chain; (2) Rotate: rotation of rope, straw and wood enrichments; (3) Stimulus: rotation of enrichments (as in Rotate) with an associative stimulus (bell or whistle); and (4) Control: no enrichment, with each treatment lasting 12 days. Six groups of 20 ± 2 sows were studied from weeks 6 to 14 of gestation in pens with one electronic sow feeder. Each group received all treatments in random order. Six focal animals (3 dominant and 3 subordinate) were selected per pen using a feed competition test. Digital photos were collected at 10 min intervals for 8 h (between 8 a.m. and 4 p.m.) on 4 days/treatment (d 1, 8, 10 and 12) to record interactions with enrichment. Skin lesions were assessed on days 1 and 12, and saliva cortisol samples collected in weeks 6, 10 and 14 of gestation on focal pigs. Sows spent more time in contact with enrichments in Rotate and Stimulus treatments than Constant. Enrichment treatments did not influence lesion scores. Subordinate sows spent more time standing and near enrichments than dominants. Subordinate sows also received more skin lesions and had higher salivary cortisol concentrations than dominants. These results indicate that access to enrichment is valued by sows but can result in greater aggression directed towards subordinates.

Effects of social rank on welfare and performance of gestating sows housed in two group sizes

Objectives: To compare welfare and performance among low-, middle-, and high-ranking sows in two group sizes of gestation pens. Materials and methods: Pregnant sows (n = 152) were allocated to four pens of 26 sows (large-group pen) and eight pens of six sows (small-group pen) with floor feeding. Social rank was based on outcomes of aggression during mixing. Skin lesions were assessed for all sows and salivary cortisol concentrations were measured for 32 focal sows. Performance during gestation and lactation was recorded for all sows. Results: Across the two group sizes, low-ranking sows fought less frequently, but had higher salivary cortisol concentrations and sustained similar skin lesions at mixing compared to high-ranking sows. Low-ranking sows had more skin lesions 5 weeks after mixing, gained less weight during gestation, and had lower body weight before farrowing than high-ranking sows. Social rank did not affect litter size farrowed, litter size weaned, or litter weight at weaning. Implications: Under the conditions of this study, regardless of the group size adopted, low-ranking sows have poorer welfare than high-ranking sows in a group housing system with floor feeding, demonstrated by their having more skin lesions, higher cortisol levels, and less weight gain during the gestation period than high-ranking sows.

Different stressors elicit different responses in the salivary biomarkers cortisol, haptoglobin, and chromogranin A in pigs

Most commonly, salivary cortisol is used in pig stress assessment, alternative salivary biomarkers are scarcely studied. Here, salivary cortisol and two alternative salivary biomarkers, haptoglobin and chromogranin A were measured in a pig stress study. Treatment pigs (n = 24) were exposed to mixing and feed deprivation, in two trials, and compared to untreated controls (n = 24). Haptoglobin differed for feed deprivation vs control. Other differences were only found within treatment. Treatment pigs had higher salivary cortisol concentrations on the mixing day (P < 0.05). Chromogranin A concentrations were increased on the day of refeeding (P < 0.05). Haptoglobin showed a similar pattern to chromogranin A. Overall correlations between the salivary biomarkers were positive. Cortisol and chromogranin A were moderately correlated (r = 0.49, P < 0.0001), correlations between other markers were weaker. The present results indicate that different types of stressors elicited different physiological stress responses in the pigs, and therefore including various salivary biomarkers in stress evaluation seems useful.

The impact of dystocia on dairy calf health, welfare, performance and survival

Up to one-third of dairy calves are born after dystocia and this is a major cause of calf mortality. This study investigated the neonatal physiology, survival, health and subsequent growth of dairy calves following dystocia and is the first longitudinal study to analyse multiple effects and to look beyond the perinatal period. A total of 455 live born Holstein calves (N: No assistance, n=360; FN: Farmer assistance but normally presented calf, n=82; FM: Farmer assistance of malpresented calf, n=13) were followed from birth to first service (heifers) or until leaving the farm (bulls). Compared to N calves, FN and FM animals had higher salivary cortisol concentrations at day 1 (P<0.001) and FN calves had lower passive immune transfer (P=0.03). Dystocia had no biologically significant impact on rectal temperature throughout the first 4 days (P>0.05). During the first 60 days, FM calves had a higher proportion of days with non-routine health treatments (P<0.05) and, by the time of weaning, mortality in FN and FM heifers was higher than in N calves (2.8×; P<0.01). However, in surviving calves, growth to first service was not affected by dystocia category (P>0.05). Calves which survive dystocia experience lower passive immunity transfer, higher mortality and higher indicators of physiological stress. Such calves have poorer welfare in the neonatal period and possibly beyond. Strategies need to be implemented to improve the subsequent health and welfare of such calves and to lower the incidence of dystocia.

Circadian Rhythm of Salivary Cortisol in Asian Elephants (Elephas maximus): A Factor to Consider During Welfare Assessment

Elevated glucocorticoid levels during an extended time period might be a stress indicator in nonhuman animals. Therefore, knowledge of the circadian pattern of cortisol secretion is very important to correctly interpret data obtained for welfare assessment of animals in captivity through salivary cortisol. In order to define the circadian rhythm of salivary cortisol secretion in the Asian elephant (Elephas maximus), morning and evening saliva samples of 3 Asian elephants were collected and analyzed by radioimmunoassay. Significantly higher salivary cortisol concentrations were found in the morning than in the evening in all individuals. These results show that salivary cortisol of Asian elephants follows a diurnal pattern of secretion, which could be taken into account when using this methodology to assess welfare in captive Asian elephants.

Ecological Momentary Assessment of Maternal Cortisol Profiles Over a Multiple-Day Period Predicts the Length of Human Gestation

Biobehavioral models of prenatal stress highlight the importance of the stress-related hormone cortisol. However, the association between maternal cortisol levels and the length of human gestation requires further investigation because most previous studies have relied on one-time cortisol measures assessed at varying gestational ages. This study assessed whether ecological momentary assessment (EMA) of cortisol sampling improves the ability to predict the length of human gestation. In addition, associations between EMA-based measures of psychological state (negative affect) with cortisol levels during pregnancy were assessed. For a 4-day period, 25 healthy pregnant women (mean gestational age at assessment = 23.4 [standard deviation = 9.1] weeks) collected seven salivary samples per day for the assessment of cortisol and provided a rating of negative affect every waking hour using an electronic diary. Higher salivary cortisol concentrations at awakening and throughout the day (p = .001), as well as a flatter cortisol response to awakening (p = .005), were associated with shorter length of gestation. Women who delivered an infant at 36 weeks of gestations had 13% higher salivary cortisol levels at awakening than women who delivered an infant at 41 weeks of gestation. The EMA-based measure of negative affect was associated with higher cortisol throughout the day (p = .006) but not to gestational length (p = .641). The one-time measure of cortisol was not associated with length of gestation, and traditional retrospective recall measures of negative affect were not associated with cortisol. Our findings support the ecological validity of repeated ambulatory assessments of cortisol in pregnancy and their ability to improve the prediction of adverse birth outcomes.

The Impact of Early Maternal Presence on Child Development and the Stress Response System

Early life experiences may have enduring effects on human biological development. Premature infants aged 6 to 12 months cared for in incubators (control group, C) shortly after delivery were compared with premature newborns cared for using the kangaroo method (experimental group, E), characterized by consistent skin-to-skin contact. We found that groups C (n = 15) and E (n = 27) were comparable at birth. Logistic regression analysis showed that Group C infants had higher salivary cortisol concentrations and were shorter as compared with Group E infants. These findings are consistent with experimental findings showing that differences on early maternal presence lead to enduring biological consequences.

Levels of salivary stress markers in patients with anxiety about halitosis

Objective To investigate the relationship between salivary stress markers and mental stress states in patients complaining of oral malodour. The utility of the salivary stress markers in assessment of mental conditions of those patients was also investigated. Design The study population included 74 patients, aged 20–59 years, who complained of oral malodour and were referred to the Breath Odor Clinic at Tokushima University Hospital. Patients were classified into two groups, genuine halitosis (GH) and psychosomatic halitosis (PH), according to the results of organoleptic rating measurement. All patients were subjected to examination by the Cornell Medical Index (CMI) Health Questionnaire. Resting saliva was collected and levels of salivary IgA, cortisol and chromogranin A were determined by ELISA. Twenty-three volunteers not complaining of halitosis were included as the control group. Kruskal–Wallis test and Mann–Whitney's U-test were used for statistical analysis. Results A significant increase was observed in the concentrations of salivary cortisol in the PH group as compared with GH and control groups ( p < 0.05). Concentrations of IgA and chromogranin A in saliva were not significantly different among the three groups. In addition, higher salivary cortisol concentrations were found in CMI scale III and IV (tendency towards neurosis) than in scale I and II (normal) ( p < 0.05). Since salivary cortisol reflects a status of chronic stress condition, psychosomatic halitosis might be closely related to this state of chronic stress. Conclusions Determination of cortisol levels in saliva may provide useful information for evaluating the mental status of patients complaining of halitosis.

Alterations in Diurnal Salivary Cortisol Rhythm in a Population-Based Sample of Cases With Chronic Fatigue Syndrome

To examine diurnal salivary cortisol rhythms and plasma IL-6 concentrations in persons with chronic fatigue syndrome (CFS), persons not fulfilling a diagnosis of CFS (we term them cases with insufficient symptoms or fatigue, ISF) and nonfatigued controls (NF). Previous studies of CFS patients have implicated the hypothalamic-pituitary-adrenal axis and the immune system in the pathophysiology of CFS, although results have been equivocal. Twenty-eight people with CFS, 35 persons with ISF, and 39 NF identified from the general population of Wichita, Kansas, were admitted to a research ward for 2 days. Saliva was collected immediately on awakening (6:30 AM), at 08:00 AM, 12 noon, 4:00 PM, 8:00 PM and at bedtime (10:00 PM) and plasma was obtained at 7:30 AM. Salivary cortisol concentrations were assessed using radioimmunoassay, and plasma IL-6 was measured using sandwich enzyme-linked immunosorbent assay. People with CFS demonstrated lower salivary cortisol concentrations in the morning and higher salivary cortisol concentrations in the evening compared with both ISF and NF groups indicating a flattening of the diurnal cortisol profile. Mean plasma IL-6 concentrations were highest in CFS compared with the other groups, although these differences were no longer significant after controlling for BMI. Attenuated decline of salivary cortisol concentrations across the day and IL-6 concentration were associated with fatigue symptoms in CFS. These results suggest an altered diurnal cortisol rhythm and IL-6 concentrations in CFS cases identified from a population-based sample.

Effects of rearing conditions on behavioural and physiological responses of pigs to preslaughter handling and mixing at transport

The physiological and behavioural responses of slaughter pigs reared in either a barren environment or in an enriched environment (larger pens with straw bedding) to preslaughter handling and mixing at transport were studied. Enriched-reared pigs had higher salivary cortisol concentrations in the home pen before and after transport than barren housed pigs, but at the end of the lairage period salivary cortisol concentrations did not differ between enriched- and barren-housed pigs. In pigs reared in a barren environment, salivary cortisol concentrations increased significantly after transport and being in lairage, as compared to home pen salivary cortisol concentrations. In pigs reared in an enriched environment, salivary cortisol concentrations did not significantly change after any stage of preslaughter handling and transport as compared with home pen salivary cortisol concentrations. In the truck, pigs reared in a barren environment tended to spend more time walking, standing and manipulating other pigs than enriched-reared pigs. Moreover, pigs reared in a barren environment tended to spend more time walking and fighting in lairage than enriched-reared pigs. Results showed that rearing conditions may affect the behavioural and physiological responses of pigs to preslaughter handling and mixing at transport. The tendency for increased manipulation of pen mates and fighting, and the significant increases in salivary cortisol in response to mixing at transport and being in lairage in pigs reared in a barren environment indicate that pigs reared in a barren environment are likely to experience more stress during common preslaughter procedures than pigs reared in an enriched environment. Key words: Behaviour, cortisol, housing conditions, pigs, slaughter

Stress response in school-age children who have been growth retarded since early childhood

BackgroundApproximately 39% of children aged <5 y in developing countries are growth retarded (stunted) and many have poor mental development and behavioral abnormalities. Animal research suggests that an altered stress response may contribute to the negative outcomes following undernutrition. ObjectiveWe tested the hypothesis that stunted children have higher salivary cortisol concentrations and heart rates and altered behavior when compared with nonstunted children when social background was controlled for. DesignWe compared 30 stunted with 24 nonstunted children, all of whom were 8-10 y old and lived in the same poor areas of Kingston, Jamaica. All subjects were participants in a prospective, longitudinal, case-control study of children who were stunted in early childhood. We administered a test session (including psychologic and physical stressors), measured baseline and response levels of salivary cortisol and heart rate, and observed behavior. ResultsCompared with nonstunted children, stunted children had higher salivary cortisol concentrations (P = 0.007), had higher heart rates during the psychologic test session (P = 0.03), exhibited enhanced cardiovascular responsivity to a physical stressor (P = 0.04), vocalized less, were more inhibited, and were less attentive. After birth weight or social background and maternal and child intelligence quotients were controlled for, the differences in cortisol concentration and cardiovascular reactivity remained significant. ConclusionsOur findings suggest that consistent growth retardation since early childhood affects physiologic arousal, which, we speculate, may contribute to the poor cognitive functioning and immune responses of stunted children and the relation between adult short stature and increased cardiovascular risk. Am J Clin Nutr 1998;68:691–8.

The Effects of Morning Naps, Car Trips, and Maternal Separation on Adrenocortical Activity in Human Infants

3 studies of adrenocortical activity in healthy 9-month-old infants were conducted to examine unanticipated results obtained in previous research. In the first study, morning naps were examined and found to be associated with significant decreases in salivary cortisol. These decreases were followed by a significant return to prenap cortisol concentrations. In the second study, riding for 40 min in the car was also shown to significantly lower salivary cortisol concentrations. This effect was obtained both for infants who did and who did not sleep during the car trip. In the third study, the effect of 30 min of maternal separation in the laboratory on salivary cortisol was compared to the effect of 30 min of play with mother present. Separation resulted in significantly higher salivary cortisol concentrations as compared to play with mother present. In general, correlations between cortisol and behavior were found to be nonsignificant under conditions that did not produce stress elevations in cortisol, while less positive, more distressed behaviour was significantly correlated with cortisol under separation or stress conditions.