Three steps toward improving the measurement of behavior in behavioral phenotype research

Adaptive functioning in Williams syndrome and its relation to demographic variables and family environment

This study assessed adaptive functioning in children and adults with Williams syndrome. The aims were to: (1) profile adaptive functioning; (2) investigate the relationship between adaptive functions and gender, CA, and IQ; (3) investigate the relationship between levels of adaptive functioning and family environment characteristics. In line with predictions: (1) there was extensive variability in adaptive functions; (2) neither gender nor IQ were significantly related to adaptive skills, but Communication skills and Interpersonal Relationship skills failed to make appropriate gains relative to same aged peers and (3) adaptive functioning was significantly related to family environment. Practical and clinical implications are discussed.

Identifying large-scale brain networks in fragile X syndrome

IMPORTANCE

Fragile X syndrome (FXS) is an X-linked neurogenetic disorder characterized by a cognitive and behavioral phenotype resembling features of autism spectrum disorder. Until now, research has focused largely on identifying regional differences in brain structure and function between individuals with FXS and various control groups. Very little is known about the large-scale brain networks that may underlie the cognitive and behavioral symptoms of FXS.

OBJECTIVE

To identify large-scale, resting-state networks in FXS that differ from control individuals matched on age, IQ, and severity of behavioral and cognitive symptoms.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional, in vivo neuroimaging study conducted in an academic medical center. Participants (aged 10-23 years) included 17 males and females with FXS and 16 males and females serving as controls.

MAIN OUTCOMES AND MEASURES

Univariate voxel-based morphometric analyses, fractional amplitude of low-frequency fluctuations (fALFF) analysis, and group-independent component analysis with dual regression.

RESULTS

Patients with FXS showed decreased functional connectivity in the salience, precuneus, left executive control, language, and visuospatial networks compared with controls. Decreased fALFF in the bilateral insular, precuneus, and anterior cingulate cortices also was found in patients with FXS compared with control participants. Furthermore, fALFF in the left insular cortex was significantly positively correlated with IQ in patients with FXS. Decreased gray matter density, resting-state connectivity, and fALFF converged in the left insular cortex in patients with FXS.

CONCLUSIONS AND RELEVANCE

Fragile X syndrome results in widespread reductions in functional connectivity across multiple cognitive and affective brain networks. Converging structural and functional abnormalities in the left insular cortex, a region also implicated in individuals diagnosed with autism spectrum disorder, suggests that insula integrity and connectivity may be compromised in FXS. This method could prove useful in establishing an imaging biomarker for FXS.

Reciprocity among maternal distress, child behavior, and parenting: transactional processes and early childhood risk

Transactional theories support that parent-child processes are best studied in conjunction with one another, addressing their reciprocal influence and change across time. This study tested a longitudinal, autoregressive model exploring bidirectional relations among maternal symptomatology, child internalizing/externalizing symptoms, and maternal sensitivity during the preschool period (child ages 3 to 5 years), comparing relations among families of typically developing children and children with developmental risk. This study included 250 families, 110 of which had a child with early developmental delay. Analyses utilized data from maternal report, father report, and observational methods. The results indicated significant stability in maternal symptomatology, child internalizing/externalizing symptoms, and maternal sensitivity over time. Support for bidirectional effects between maternal symptomatology and child internalizing symptoms was found specifically for mothers of children with developmental risk. Maternal symptomatology was found to mediate the influence of child internalizing and externalizing symptoms on maternal sensitivity. The findings underscore critical transactional processes within families of children with early developmental risk that connect increased maternal symptomatology to emerging child internalizing symptoms during the preschool period.

Developmental risk and young children's regulatory strategies: predicting behavior problems at age five

Children with early developmental delays are at heightened risk for behavior problems and comorbid psychopathology. This study examined the trajectories of regulatory capabilities and their potentially mediating role in the development of behavior problems for children with and without early developmental delays. A sample of 231 children comprised of 137 typically developing children and 94 children with developmental delays were examined during mildly frustrating laboratory tasks across the preschool period (ages 3-5). Results indicated that children with delays had greater use of maladaptive strategies (distraction, distress venting) and lower use of adaptive strategies (constructive coping) than typically developing children. For both groups, strategies had similar rates of growth across time; maladaptive strategies decreased and adaptive strategies increased. The intercept of strategy use, but not the slope, was found to mediate the relation between developmental risk and externalizing behaviors. Findings support that dysregulation, rather than the developmental risk, may be responsible for the high levels of comorbid psychopathology.

The down syndrome behavioral phenotype: implications for practice and research in occupational therapy

ABSTRACT Down syndrome (DS) is the most common chromosomal cause of intellectual disability. The genetic causes of DS are associated with characteristic outcomes, such as relative strengths in visual-spatial skills and relative challenges in motor planning. This profile of outcomes, called the DS behavioral phenotype, may be a critical tool for intervention planning and research in this population. In this article, aspects of the DS behavioral phenotype potentially relevant to occupational therapy practice are reviewed. Implications and challenges for etiology-informed research and practice are discussed.

Genes, brain development and psychiatric phenotypes in velo-cardio-facial syndrome

Velo-cardio-facial syndrome (VCFS) has been in the focus of intensive research over the last 15 years. The syndrome represents a homogeneous model for studying the effect of a decreased dosage of genes on the development of brain structure and function and, consequently, on the emergence of schizophrenia-like psychotic disorder. In this review, we describe the psychiatric phenotype of children, adolescents, and young adults with VCFS. We redefine the concept of "behavioral phenotype" and suggest that psychosis fulfills the criteria of a behavioral phenotype of the syndrome. Identifying the risk factors for the emergence of psychosis in VCFS is a major goal of several large-scale longitudinal studies that are currently underway. We review the knowledge gained so far about risk factors for psychosis in VCFS, including early neuropsychiatric symptoms, development of brain structure and function, and the effect of a reduced dosage of genes from the 22q11 deletion region. Although the brain structure in subjects with VCFS is not drastically different from typically developing controls, newer imaging modalities that measure white matter tracts, cortical thickness, and cortical gyrification are likely to identify more subtle and specific neuroanatomical substrates of the syndrome. Among the 24 genes within the deletion region, the role of catechol-O-methyltransferase (COMT) on the VCFS phenotype has been investigated in depth. The findings suggest that because of haploinsufficiency of the COMT gene individuals with VCFS are exposed to a high level of prefrontal dopamine, and this interferes with their prefrontal cognitive functioning and may contribute to their high rate of psychosis and other psychiatric disorders. The other genes and environmental factors that shape the unique neuropsychiatric phenotype of VCFS are yet to be discovered.

The changing impact of genes and environment on brain development during childhood and adolescence: initial findings from a neuroimaging study of pediatric twins

Human brain development is created through continuing complex interactions of genetic and environmental influences. The challenge of linking specific genetic or environmental risk factors to typical or atypical behaviors has led to interest in using brain structural features as an intermediate phenotype. Twin studies in adults have found that many aspects of brain anatomy are highly heritable, demonstrating that genetic factors provide a significant contribution to variation in brain structures. Less is known about the relative impact of genes and environment while the brain is actively developing. We summarize results from the ongoing National Institute of Mental Health child and adolescent twin study that suggest that heritability of different brain areas changes over the course of development in a regionally specific fashion. Areas associated with more complex reasoning abilities become increasingly heritable with maturation. The potential mechanisms by which gene-environment interactions may affect heritability values during development is discussed.