Attenuated relationship between salivary oxytocin levels and attention to social information in adolescents and adults with autism spectrum disorder: a comparative study.

BACKGROUND: Previous research studies have assessed the relationship between attention to social information and peripheral (e.g., plasma and salivary) oxytocin (OT) levels in typically developing (TD) children and children with autism spectrum disorder (ASD). A relationship between them was observed in TD children, but not in children with ASD. However, this relationship remains unexamined in other age groups. To clarify whether this lack of association is maintained throughout development in individuals with ASD, we aimed to assess the relationship between salivary OT levels and attention to social information in adolescents and adults with and without ASD. METHODS: We recruited male adolescents and adults with ASD (n = 17) and TD participants (n = 24). Using the all-in-one eye-tracking system Gazefinder, we measured the percentage fixation time allocated to social information. We also measured the salivary OT levels and Autism Spectrum Quotient (AQ) of participants. Subsequently, we confirmed group differences and conducted a correlation analysis to investigate the relationships between these three measures. RESULTS: Salivary OT levels did not show any significant difference between the ASD and TD groups and were negatively correlated with the AQ in the whole-group analysis, but not in within-group analysis. Individuals with ASD had significantly lower percentage fixation times than did TD individuals for eye regions in human faces with/without mouth motion, for upright biological motion, and for people regions in the people and geometry movies. The percentage of fixation for geometric shapes in the people and geometry movies was significantly higher in the ASD than in the TD group. In the TD group, salivary OT levels were positively correlated with percentage fixation times for upright biological motion and people and negatively correlated with inverted biological motion and geometry. However, no significant correlations were found in the ASD group. CONCLUSIONS: Our exploratory results suggest that salivary OT levels in adolescents and adults with ASD are less indicative of attention to social stimuli than they are in TD adolescents and adults. It is suggested that their association is slightly weaker in adolescents and adults with ASD and that this attenuated relationship appears to be maintained throughout development.

Oxytocin efficacy is modulated by dosage and oxytocin receptor genotype in young adults with high-functioning autism: a 24-week randomized clinical trial.

Recent studies have suggested that long-term oxytocin administration can alleviate the symptoms of autism spectrum disorder (ASD); however, factors influencing its efficacy are still unclear. We conducted a single-center phase 2, pilot, randomized, double-blind, placebo-controlled, parallel-group, clinical trial in young adults with high-functioning ASD, to determine whether oxytocin dosage and genetic background of the oxytocin receptor affects oxytocin efficacy. This trial consisted of double-blind (12 weeks), open-label (12 weeks) and follow-up phases (8 weeks). To examine dose dependency, 60 participants were randomly assigned to high-dose (32 IU per day) or low-dose intranasal oxytocin (16 IU per day), or placebo groups during the double-blind phase. Next, we measured single-nucleotide polymorphisms (SNPs) in the oxytocin receptor gene (OXTR). In the intention-to-treat population, no outcomes were improved after oxytocin administration. However, in male participants, Clinical Global Impression-Improvement (CGI-I) scores in the high-dose group, but not the low-dose group, were significantly higher than in the placebo group. Furthermore, we examined whether oxytocin efficacy, reflected in the CGI-I scores, is influenced by estimated daily dosage and OXTR polymorphisms in male participants. We found that >21 IU per day oxytocin was more effective than ⩽21 IU per day, and that a SNP in OXTR (rs6791619) predicted CGI-I scores for ⩽21 IU per day oxytocin treatment. No severe adverse events occurred. These results suggest that efficacy of long-term oxytocin administration in young men with high-functioning ASD depends on the oxytocin dosage and genetic background of the oxytocin receptor, which contributes to the effectiveness of oxytocin treatment of ASD.

Oxytocin signal and social behaviour: comparison among adult and infant oxytocin, oxytocin receptor and CD38 gene knockout mice.

Oxytocin in the hypothalamus is the biological basis of social recognition, trust, love and bonding. Previously, we showed that CD38, a proliferation marker in leukaemia cells, plays an important role in the hypothalamus in the process of oxytocin release in adult mice. Disruption of Cd38 (Cd38 (-/-)) elicited impairment of maternal behaviour and male social recognition in adult mice, similar to the behaviour observed in Oxt and oxytocin receptor (Oxtr) gene knockout (Oxt (-/-) and Oxtr (-/-), respectively) mice. Locomotor activity induced by separation from the dam was higher and the number of ultrasonic vocalisation calls was lower in Cd38 (-/-) than Cd38( +/+) pups. However, these behavioural changes were much milder than those observed in Oxt (-/-) and Oxtr (-/-) mice, indicating less impairment of social behaviour in Cd38 (-/-) pups. These phenotypes appeared to be caused by the high plasma oxytocin levels during development from the neonatal period to 3-week-old juvenile mice. ADP-ribosyl cyclase activity was markedly lower in the knockout mice from birth, suggesting that weaning for mice is a critical time window of plasma oxytocin differentiation. Breastfeeding was an important exogenous source of plasma oxytocin regulation before weaning as a result of the presence of oxytocin in milk and the dam's mammary glands. The dissimilarity between Cd38 (-/-) infant behaviour and those of Oxt (-/-) or Oxtr (-/-) mice can be explained partly by this exogenous source of oxytocin. These results suggest that secretion of oxytocin into the brain in a CD38-dependent manner may play an important role in the development of social behaviour.

High prevalence of bipolar disorder comorbidity in adolescents and young adults with high-functioning autism spectrum disorder: a preliminary study of 44 outpatients.

BACKGROUND: Psychiatric comorbidity of autism spectrum disorder (ASD) has not been well examined. METHODS: Mood disorders in 44 consecutive outpatients with high-functioning ASD were examined at a university hospital according to DSM-IV. Inclusion criteria were an IQ of 70 or higher on the Wechsler Intelligence Scale and age of 12 years or over. RESULTS: Sixteen patients (36.4%) were diagnosed with mood disorder. Of these 16 patients, four were diagnosed as having major depressive disorder, two patients as bipolar I disorder, six patients as bipolar II disorder, and four patients as bipolar disorder not otherwise specified. Bipolar disorder accounted for 75% of cases. Twelve patients had Asperger disorder and four patients had pervasive developmental disorder not otherwise specified. None of the patients had autistic disorder. LIMITATIONS: The sample size was small. We could not use Autism Diagnostic Interview - Revised. Referral bias could not be avoided in this study. CONCLUSIONS: The major comorbid mood disorder in patients with high-functioning ASD is bipolar disorder and not major depressive disorder. The autistic spectrum may share common vulnerability genes with the bipolar spectrum.

Excessive water drinking behavior in autism.

The aim of this study was to determine the incidence of polydipsia in 49 autistic children, and also the influence of psychotropic drugs and residential factors on water drinking behavior, as compared with in 89 mentally retarded children, in schools for mentally handicapped children in Fukui prefecture. Questionnaires were used to detect polydipsia and to assess the severity of the water drinking behavior in the autistic children and mentally retarded children. The incidence of polydipsia in the autistic children tended to be higher (P = 0.074) than that in the retarded children. The severity of water drinking behavior was significantly higher in autism (P = 0.022) than in mental retardation. The majority of the autistic children with polydipsia had been taking no psychotropic drugs. The incidence of polydipsia showed no significant difference between two residential situations, i.e. 'not at home' and 'at home'. The present study suggests that polydipsia or excessive water drinking behavior occurs more often in autism than in mental retardation, possibly due to some intrinsic factor in autism itself.

[Two cases of infantile autism with intermittent water intoxication due to compulsive water drinking and episodic release of antidiuretic hormone (SIADH)].

The syndrome of water intoxication, resulting from dilutional hyponatremia and characterized by lethalgy, confusion, seizures, and coma was seen in two autistic boys living in the institution for mentally retarded children. Patient 1, a 19 year-old autistic boy showed loss of attention, inactiveness, sleepiness and delirium and then followed by overbreathing, severe vomiting and finally convulsive seizures several times, or coma, since October 1985. In August 1988, he was admitted with generalized tonic clonic convulsion associated with frequent vomiting EEG showed diffuse spike and wave complex with slow background activity. Laboratory data showed inappropriately high serum ADH level (8.5 pg/ml), low sodium concentration (121 mOsm/m/l), serum osmolality (237 mOsm/l) which was lower than urine osmolality (334 mOsm/l), and remarkable body weight gain (8.5 kg). He was diagnosed as water intoxication due to compulsive water drinking and SIADH. Diminished GH secretion to insulin-induced hypoglycemia and exaggerated prolactin response to LHRH stimulation suggested a hypothalamic lesion. Patient 2, a 17-year-old autistic boy, showed essentially the same symptoms and laboratory data as Patient 1, except that he had no epileptic discharge in EEG, and curious GH response to insulin-induced hypoglycemia. A remarkable daily body weight change suggested excessive water drinking and a possible episodic release of ADH. With mild water restriction, this became smaller. Since Patient 1 had epileptic attacks several times without hyponatremia and his EEG showed epileptic discharges, he was diagnosed as having epilepsy. Patient 2 has been seizure-free until now. Abnormality of hypothalamic or pituitary defects and polydipsia and possibility of water intoxication should always be considered when an autistic patients shows recurrent epileptic attacks or episodic strange behaviors with hyponatremia.

The prevalence of Rett syndrome in Fukui prefecture.

The present study was performed to estimate the prevalence of Rett syndrome in Fukui prefecture by sending questionnaires to special classes (classes for handicapped children in schools for normal children) and schools for mentally/physically handicapped children, and observing children suspected of having this syndrome on the basis of answers to the questionnaire. The subjects were girls aged 6-14 years who were attending 11 special classes and 7 schools for handicapped children. The prevalence of Rett syndrome was estimated to be 0.22 per 10,000 girls aged 6-14 years in Fukui prefecture, as of April 1, 1993. The prevalence noted in this study was lower than those found in previous studies in Japan and Western countries.