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Autism affects males more than females, giving rise to the idea that the influence of steroid hormones on early fetal brain development may be one important early biological risk factor. Utilizing the Danish Historic Birth Cohort and Danish Psychiatric Central Register, we identified all amniotic fluid samples of males born between 1993 and 1999 who later received ICD-10 (International Classification of Diseases, 10th Revision) diagnoses of autism, Asperger syndrome or PDD-NOS (pervasive developmental disorder not otherwise specified) (n=128) compared with matched typically developing controls. Concentration levels of Δ4 sex steroids (progesterone, 17α-hydroxy-progesterone, androstenedione and testosterone) and cortisol were measured with liquid chromatography tandem mass spectrometry. All hormones were positively associated with each other and principal component analysis confirmed that one generalized latent steroidogenic factor was driving much of the variation in the data. The autism group showed elevations across all hormones on this latent generalized steroidogenic factor (Cohen's d=0.37, P=0.0009) and this elevation was uniform across ICD-10 diagnostic label. These results provide the first direct evidence of elevated fetal steroidogenic activity in autism. Such elevations may be important as epigenetic fetal programming mechanisms and may interact with other important pathophysiological factors in autism.

Autism spectrum conditions have been hypothesized to be an exaggeration of normal male low-empathizing and high-systemizing behaviors. We tested this hypothesis at the molecular level by performing comprehensive multi-analyte profiling of blood serum from adult subjects with Asperger's syndrome (AS) compared with controls. This led to identification of distinct sex-specific biomarker fingerprints for male and female subjects. Males with AS showed altered levels of 24 biomarkers including increased levels of cytokines and other inflammatory molecules. Multivariate statistical classification of males using this panel of 24 biomarkers revealed a marked separation between AS and controls with a sensitivity of 0.86 and specificity of 0.88. Testing this same panel in females did not result in a separation between the AS and control groups. In contrast, AS females showed altered levels of 17 biomarkers including growth factors and hormones such as androgens, growth hormone and insulin-related molecules. Classification of females using this biomarker panel resulted in a separation between AS and controls with sensitivities and specificities of 0.96 and 0.83, respectively, and testing this same panel in the male group did not result in a separation between the AS and control groups. The finding of elevated testosterone in AS females confirmed predictions from the 'extreme male brain' and androgen theories of autism spectrum conditions. We conclude that to understand the etiology and development of autism spectrum conditions, stratification by sex is essential.

The objective of this study is to examine the occurrence and characteristic features of obsessive-compulsive behaviours in children and adolescents with Asperger syndrome (AS), with respect to a matched obsessive compulsive disorder group (OCD) and a typically developing control group (CG). For this purpose, 60 subjects (20 OCD; 18 AS; 22 CG), aged 8-15 years, matched for age, gender and IQ were compared. AS and OCD patients were diagnosed according to the DSM-IV-TR criteria. The Autism Diagnostic Interview-Revised and the Autism Diagnostic Observation Schedule were used to assist in the AS diagnosis; the WISC-R was administered to assess IQ. Obsessive and compulsive symptoms were evaluated by using the Children's Yale-Brown Obsessive-Compulsive Scale (CY-BOCS). None of the AS children received a formal diagnosis of OCD. The AS group presented significantly higher frequencies of Hoarding obsessions and Repeating, Ordering and Hoarding compulsions compared to CG. The OCD group, in turn, reported significantly higher frequencies of Contamination and Aggressive obsessions and Checking compulsions compared to both the AS group and CG. As expected, the OCD group displayed a higher severity of symptoms (Moderate level of severity) than did the AS group (Mild level of severity). Finally, in our sample, neither the OCD group nor the AS group demonstrated a completely full awareness of the intrusive, unreasonable and distressing nature of symptoms, and the level of insight did not differ between the OCD group and CG, although an absence of insight was observed in the AS group. Children with AS showed higher frequencies of obsessive and compulsive symptoms than did typically developing children, and these features seem to cluster around Hoarding behaviours. Additionally, different patterns of symptoms emerged between the OCD and AS groups. Finally, in our sample, the level of insight was poor in both the OCD and the AS children. Further research should be conducted to better understand the characteristics of repetitive thoughts and behaviours in autism spectrum disorders, and to clarify the underlying neurobiological basis of these symptoms.