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Journal Article 2010; 31(5): 685-689 PubMed PMID: 21178943 Citation  Keywords:  Autonomic Nervous System:physiology, Circadian Rhythm:physiology, Electrocardiography, Female, Humans, Hydrocortisone:secretion, Male, Saliva:metabolism, Sleep:physiology, Sympathetic Nervous System:physiology, Time Factors, Vagus Nerve:physiology, Wakefu.   

: The current study focuses on autonomic nervous system activity during sleep as a physiological aspect of sleep quality, and investigated the associations between the cortisol awakening response (CAR) and autonomic activity during sleep and after awakening. Ambulatory electrocardiograms were obtained from 20 participants, who also provided saliva samples (at the time of awakening, and 30, 45, and 60 min after awakening) and rated the subjective quality of their sleep at home. Autonomic activity was assessed with the Lorenz plot indices, cardiac sympathetic index (CSI) and cardiac vagal index. Total salivary cortisol secretion after awakening was calculated as area under the curve with respect to ground (AUC(G)) and increase (AUC(I)). After controlling for confounding factors, including sleep duration and awakening time, cortisol AUC(G) and AUC(I) were both found to be negatively correlated with CSI during the 30 min before and after awakening: before (r = -0.526 and -0.601 respectively) and after (r = -0.540 and -0.493 respectively). Self-reported sleep quality was not associated with the CAR. These results suggest that the CAR is negatively affected by basal sympathetic activity immediately before and after awakening, but not affected by subjective sleep quality. Physiological arousals around the time of awakening might inhibit the CAR....

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Journal Article 2007; 28(5): 662-665 PubMed PMID: 17984929 Citation  Keywords:  Adolescent, Adult, Altruism, Amylases:metabolism, Decision Making:physiology, Games, Experimental, Humans, Male, Reference Values, Reward, Saliva:metabolism, Self Concept, Social Perception,.   

OBJECTIVE: Little is known regarding the relationship between social evaluation-induced neuroendocrine responses and generosity in game-theoretic situations. Previous studies demonstrated that reputation formation plays a pivotal role in prosocial behavior. This study aimed to examine the relationships between a social evaluation-induced salivary alpha-amylase (sAA) response and generosity in the dictator game. The relationship is potentially important in neuroeconomics of altruism and game theory.

METHODS: We assessed sAA and allocated money in the dictator game in male students with and without social evaluation. RESULTS Social evaluation-responders allocated significantly more money than controls; while there was no significant correlation between social evaluation-induced sAA elevation and the allocated money.

CONCLUSIONS: Social evaluation significantly increases generosity in the dictator game, and individual differences in trait characteristics such as altruism and reward sensitivity may be important determinants of generosity in the dictator game task....

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Comparative Study 2007; 28(4): 445-448 PubMed PMID: 17693971 Citation  Keywords:  Adolescent, Adult, Autistic Disorder:physiopathology, Circadian Rhythm:physiology, Cognition:physiology, Empathy, Female, Humans, Hydrocortisone:metabolism, Logic, Male, Psychopathology, Saliva:metabolism, Sex Characteristics, Social Adjustment,.   

OBJECTIVE: Little is known regarding the relationship between cortisol (a stress hormone) levels and psychological cognitive styles. Baron-Cohen proposed two fundamental cognitive styles, which are measured by the Empathy Quotient (EQ) and the Systemizng Quotient (SQ). Previous studies have examined the influences of prenatal testosterone exposure on EQ and SQ scores. This study aimed to examine the relationships between morning cortisol levels and EQ and SQ scores, and the 'brain types' which were determined by two quotients in both sexes. These relationships are potentially important in the developmental psychopathology of autism and neuroeconomics of empathy.

METHODS: We assessed morning cortisol levels with LC/MS (liquid chromatography-mass spectrometry) and ESQ in healthy male and female university students.

CONCLUSIONS: Results indicate clear sex differences between brain types: i.e. E-type males and S-type females (participants with atypical cognitive styles) have significantly higher cortisol levels than S-type males and E-type females (participants with typical cognitive styles). Implications for the role of sex in social adaptation of autistic patients are discussed....

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Journal Article 2007; 28(4): 395-400 PubMed PMID: 17693970 Citation  Keywords:  Adult, Case-Control Studies, Circadian Rhythm:physiology, Depressive Disorder, Major:drug therapy, Female, Fluoxetine:therapeutic use, Humans, Male, Psychiatric Status Rating Scales, Saliva:metabolism, Serotonin:metabolism, Serotonin Uptake Inhibitors:the.   

OBJECTIVES: The present study aimed to explore the circadian rhythm of salivary serotonin in patients with major depressive disorder before and after treatment with fluoxetine and its relationship with clinical therapeutic effect.

METHODS: This study investigated salivary serotonin in 13 outpatients with major depressive disorder and age- and sex-matched healthy controls. Depressed patients received six weeks fluoxetine treatment (20 mg/day), saliva was collected before and four weeks after treatment. A total of 8 time-point salivary serotonin was measured across the whole day. Multi-oscillator cosinor model was used to fit the rhythms.

RESULTS: Serotonin concentration in saliva ranged from 0.32 ng/ml to 9.62 ng/ml. Salivary serotonin showed prominent circadian rhythm in 91% depressed patients and 92% healthy subjects. Circadian amplitude tend to be higher after fluoxetine treatment in depressed patients, so as the ultradian cycle amplitude. The serotonin circadian amplitude (After minus Before) was positively correlated with the decrease of Zung Self-Rating Depression Scale(SDS) scores at day 42 whereas there was no such correlation at day 28. There was no significant difference in the parameters of mesor, acrophase, harmonic and area under curve among three groups.

CONCLUSIONS: Salivary serotonin in patients with major depressive disorder showed clear circadian rhythm. The relationship between the increase of salivary serotonin amplitude and clinical response deserve further study....

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Controlled Clinical Trial 2007; 28(1): 28-32 PubMed PMID: 17277729 Citation  Keywords:  Adult, Antidepressive Agents, Second-Generation:pharmacology, Circadian Rhythm:drug effects, Depressive Disorder, Major:drug therapy, Female, Fluoxetine:pharmacology, Humans, Male, Melatonin:metabolism, Psychiatric Status Rating Scales, Saliva:metabolism,.   

OBJECTIVES: The purpose of this study is to explore the response of melatonin circadian rhythm to fluoxetine treatment and its relationship with clinical therapeutic effect.

METHODS: This study investigated salivary melatonin in 13 outpatients with major depressive disorder and age- and sex-matched healthy controls. Depressed patients received six weeks fluoxetine (20 mg/day) treatment, and saliva was collected before and four weeks after treatment. In sampling days, a total of 12 time-point salivary melatonin was measured over 24-hours. Multioscillator cosinor model was used to fit the rhythms.

RESULTS: There was no difference of circadian melatonin rhythms in depressed patients, and melatonin was not significantly lower after fluoxetine treatment. To our surprise, the melatonin amplitude (Before minus After) was positively correlated with the improvement in Hamilton Depression Rating Scale (HDRS) scores at day 42 whereas there was no such correlation at day 28.

CONCLUSIONS: Melatonin rhythms were similar between depressed patients and matched healthy controls. The interesting finding that the difference of salivary melatonin amplitude was correlated with the clinical improvement after six weeks fluoxetine treatment deserve further study....

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Journal Article 2006; 27(4): 439-444 PubMed PMID: 16891992 Citation  Keywords:  Adult, Choice Behavior:physiology, Decision Making:physiology, Economics, Humans, Impulsive Behavior:metabolism, Male, Nonlinear Dynamics, Risk-Taking, Saliva:metabolism, Surveys and Questionnaires, Testosterone:metabolism, Time Factors,.   

OBJECTIVES: Although impulsivity has been associated with androgens (e.g., testosterone), little is known regarding the relationship between testosterone levels and impulsivity in intertemporal choice (delay discounting). This study was aimed to examine the relationship between delay discounting of gains and losses and testosterone levels, which is of interest in neuroendocrinology and neuroeconomics.

METHODS: We assessed degrees to which delayed monetary gains and losses were discounted (hyperbolic discounting rate) in healty male students (age: 22.4+/-2.67). Participants' salivary testosterone levels were also assessed by utilizing liquid chromatography/mass spectroscopy (LC/MS) method.

RESULTS: Non-linear curve fitting analysis showed an inverted-U relationship between delay discounting of gains and salivary testosterone levels; while no relationship between salivary testosterone levels and delay discounting of losses was observed.

CONCLUSIONS: The results indicate that (i) testosterone may enhance delay discounting rate of gains in non-impulsive subjects, (ii) testosterone may have an opposite (reducing) effect on delay discounting rate of gains in impulsive subjects, and (iii) testosterone is unrelated to subject's sensitivity to future bad outcomes. Implications for evaluating the effects of testosterone treatment and anti-androgenic therapy on impulsive behavior often observed in psychiatrics (e.g., pathological gambling, credit card debt, substance misuse, and needle-sharing) are discussed....

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Clinical Trial 2005; 26(5): 599-602 PubMed PMID: 16264395 Citation  Keywords:  Adult, Emotions:physiology, Humans, Hydrocortisone:metabolism, Male, Memory:physiology, Saliva:metabolism,.   

OBJECTIVES: The aim of this study was to examine (i) the influence of cortisol on both prospective and retrospective memory performance and (ii) the role of emotional valence in both types of memory.

METHODS: Thirty-four male students participated in a memory task, which measured both prospective and retrospective memory performance. Baseline salivary cortisol levels were assessed.

RESULTS: Spearman's rank order correlation analysis showed a significant positive correlation between salivary cortisol levels and retrospective memory performance for neutral words. Cortisol levels were not significantly correlated with prospective memory performance for either negative nor neutral words.

CONCLUSIONS: The present results indicate chronic cortisol levels are positively associated with retrospective memory at relatively low concentration ranges, but not prospective memory, in healthy young men. Implications for evaluating the beneficial effects of low-dose cortisol treatment on posttraumatic stress disorder is discussed....

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Journal Article 2004; 25(6): 415-418 PubMed PMID: 15665802 Citation  Keywords:  Aged, Aged, 80 and over, Aging:metabolism, Analysis of Variance, Cohort Studies, Humans, Melatonin:metabolism, Middle Aged, Radioimmunoassay, Saliva:metabolism,.   

OBJECTIVES: The purpose of this study was to investigate whether melatonin levels in older cohorts within the 'aged' population were significantly lower than in younger 'aged' individuals and hence point to a possible confound in cross-sectional studies which group individuals over 55 in one category.

SETTING AND DESIGN: Melatonin levels of 35 North Queensland residents over 55 years of age living in an aged-care facility, a retirement village or the general community were compared across three age groups.

METHODS: Subjects were ten 56-65 year olds, eighteen 66-75 year olds and seven over-75 year olds. Information was obtained on sleep, awakening, medical conditions and medications, with subsequent exclusion of those with known medical conditions and/or medications. Melatonin was collected by salivary samples at 2200 hours and concentrations were determined by immunoassay.

RESULTS: Mean melatonin levels were significantly lower (p=.03) in the 'oldest' (over 75 yrs) group compared to the 'youngest' (56-65 yrs) group.

MAIN FINDINGS: The results of this preliminary study indicate that within the older population, melatonin levels appear to decline significantly with age.

CONCLUSIONS: Future studies of melatonin and ageing may benefit from a longitudinal approach, with older subjects sampled across time....

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