Behavioural genetics of childhood disorders

Autism traits, social withdrawal, and behavioral and emotional problems in a Norwegian cohort of adolescents with rare genetic disorders

BACKGROUND

Adolescents with rare genetic disorders represent a population that can be at risk in psychosocial terms. Despite its importance, the association of autism traits and social withdrawal in behavioral and emotional problems in adolescents with rare genetic disorders remains understudied.

AIM

The study aimed to empirically examine the clinical characteristics of adolescents with rare genetic disorders with a behavior theory-driven approach.

METHOD

We investigated the behavioral and emotional problems and current and lifetime autistic traits in a sample of 93 Norwegian adolescents (Mage = 13.2 years, SDage = 2.4, rangeage 10-17, 62.4% females, 37.6% males) with various rare genetic disorders. The adolescents were investigated cross-sectionally utilizing standardized psychometric questionnaires rated by their parents.

RESULTS

More current and lifetime autistic traits and social withdrawal were all associated with more internalizing problems. Further analyses demonstrated that social withdrawal partially mediated the positive association between current autistic traits and internalizing problems. In contrast, social withdrawal fully mediated the positive association between lifetime autistic traits and internalizing problems.

CONCLUSION AND IMPLICATIONS

Our results demonstrate important characteristics of adolescents with rare genetic disorders that may guide clinicians and future interventions. Social withdrawal may be prodromal to internalizing problems such as anxiety and depression. Thus, clinically addressing social withdrawal can represent a means to prevent internalizing problems in adolescents with rare genetic disorders and autistic traits.

Systematic Review: Molecular Studies of Common Genetic Variation in Child and Adolescent Psychiatric Disorders

OBJECTIVE

A systematic review of studies using molecular genetics and statistical approaches to investigate the role of common genetic variation in the development, persistence, and comorbidity of childhood psychiatric traits was conducted.

METHOD

A literature review was performed using the PubMed database, following PRISMA guidelines. There were 131 studies meeting inclusion criteria, having investigated at least one type of childhood-onset or childhood-measured psychiatric disorder or trait with the aim of identifying trait-associated common genetic variants, estimating the contribution of single nucleotide polymorphisms (SNPs) to the amount of variance explained (SNP-based heritability), investigating genetic overlap between psychiatric traits, or investigating whether the stability in traits or the association with adult traits is explained by genetic factors.

RESULTS

The first robustly associated genetic variants have started to be identified for childhood psychiatric traits. There were substantial contributions of common genetic variants to many traits, with variation in single nucleotide polymorphism heritability estimates depending on age and raters. Moreover, genetic variants also appeared to explain comorbidity as well as stability across a range of psychiatric traits in childhood and across the life span.

CONCLUSION

Common genetic variation plays a substantial role in childhood psychiatric traits. Increased sample sizes will lead to increased power to identify genetic variants and to understand genetic architecture, which will ultimately be beneficial to targeted and prevention strategies. This can be achieved by harmonizing phenotype measurements, as is already proposed by large international consortia and by including the collection of genetic material in every study.

Besonderheiten in der multiaxialen Klassifizierung, Anamnese und Psychopathologie bei Kindern und Jugendlichen mit einer Autismus-Spektrum-Störung und einer Aufmerksamkeitsdefizit-/ Hyperaktivitätsstörung

Ziel der vorliegenden Untersuchung war es, bei Kindern und Jugendlichen mit einer Autismus Spektrum Störung (ASS) ohne oder mit einer Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung (ADHS) die Achsen des Multiaxialen Klassifikationsschemas (MAS), anamnestische Daten, sowie Ergebnisse psychopathologischer Fragebogenverfahren zu vergleichen. Insgesamt wurden 120 Patienten (Gruppe ASS: n=60; Gruppe ASS+ADHS: n=60) untersucht. Es wurden eigen- und familienanamnestische Daten, die sechs Achsen der MAS und testpsychologische Ergebnisse erhoben (MBAS, FSK, SRS, CBCL). Deskriptiv konnten in der Gruppe ASS+ADHS ein gehäufter Konsum schädlicher Substanzen durch die Mütter in der Schwangerschaft erhoben werden. In beiden Gruppen fand sich bei den Vätern gehäuft eine Tätigkeit in einem akademisch-technischen Beruf. Hinsichtlich der Fragebogenverfahren zeigte sich eine höhere externalisierende Psychopathologie für die Gruppe ASS+ADHS. Passend zu bisherigen Studien konnte bei den Patienten mit ASS und ADHS eine stärker ausgeprägte psychopathologische Belastung beschrieben werden, auf die bei Diagnostik und Therapie geachtet werden sollte.

Cortisol levels in children with attention-deficit/hyperactivity disorder

Regulation of the Hypothalamus-Pituitary-Adrenal axis (HPA-axis) and its end product cortisol differs among persons with certain psychiatric disorders when compared with controls. Some reports concern Attention-Deficit/Hyperactivity Disorder (ADHD) but findings are inconclusive. In this study we collected four saliva samples during a regular weekday in children, 6-17 years old, with ADHD (n = 201) and non-affected comparisons (n = 221). Saliva cortisol was measured with radioimmunoassay technique. Clinical data were collected for diagnostic information. Subtypes and severity of symptoms were determined using parental rating scales. Children with ADHD had lower saliva cortisol levels than comparisons at waking up Median = 9.1 versus 12.7 nmol/L (p < .001), 30 min later Median = 15.8 versus 20.1 nmol/L (p < .001) and before going to bed Median = 0.8 versus 1.0 nmol/L (p = .015). No difference was found for the afternoon sample. When the study group was split into three different age groups similar results were found only for children above 10 years of age. Subtype of ADHD or co-occurring symptoms did not affect the cortisol levels. Degree of severity of ADHD symptoms was not associated with cortisol levels in the study group, other than a weak negative correlation between the afternoon sample and hyperactivity symptoms. The low cortisol levels in children with ADHD may indicate a dysregulation of the HPA-axis, for instance a down-regulation or a phase delay of the diurnal curve. The low levels may be related to the under-arousal possibly underlying several of the core symptoms of ADHD.

ADHD and autism: differential diagnosis or overlapping traits? A selective review

According to DSM-IV TR and ICD-10, a diagnosis of autism or Asperger Syndrome precludes a diagnosis of attention-deficit/hyperactivity disorder (ADHD). However, despite the different conceptualization, population-based twin studies reported symptom overlap, and a recent epidemiologically based study reported a high rate of ADHD in autism and autism spectrum disorders (ASD). In the planned revision of the DSM-IV TR, dsm5 (www.dsm5.org), the diagnoses of autistic disorder and ADHD will not be mutually exclusive any longer. This provides the basis of more differentiated studies on overlap and distinction between both disorders. This review presents data on comorbidity rates and symptom overlap and discusses common and disorder-specific risk factors, including recent proteomic studies. Neuropsychological findings in the areas of attention, reward processing, and social cognition are then compared between both disorders, as these cognitive abilities show overlapping as well as specific impairment for one of both disorders. In addition, selective brain imaging findings are reported. Therapeutic options are summarized, and new approaches are discussed. The review concludes with a prospectus on open questions for research and clinical practice.