Introduction to the special issue on behavioral phenotypes.
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Adolescent↗
Biomedical subjects
E Dykens
Publications and source records attributed to E Dykens.
Prader-Willi and Angelman syndromes: sister imprinted disorders.
Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are clinically distinct complex disorders mapped to chromosome 15q11-q13. They both have characteristic neurologic, developmental, and behavioral phenotypes plus other structural and functional abnormalities. However, the cognitive and neurologic impairment is more severe in AS, including seizures and ataxia. The behavioral and endocrine disorders are more severe in PWS, including obsessive-compulsive symptoms and hypothalamic insufficiency. Both disorders can result from microdeletion, uniparental disomy, or an imprinting center defect in 15q11-q13, although the abnormality is on the paternally derived chromosome 15 for PWS and the maternally derived 15 for AS because of genomic imprinting. Although the same gene may control imprinting for both disorders, the gene(s) causing their phenotypes differ. AS results from underexpression of a single gene, UBE3A, which codes for E6-AP, a protein that functions to transfer small ubiquitin molecules to certain target proteins, to enable their degradation. The genes responsible for PWS are not determined, although several maternally imprinted genes in 15q11-q13 are known. The most likely candidate is SNRPN, which codes for a small nuclear ribonucleoprotein, a ribosome-associated protein that controls gene splicing and thus synthesis of critical proteins in the brain. Animal models exist for both disorders. The genetic relationship between PWS and AS makes them unique and potentially highly instructive disorders that contribute substantially to the population burden of cognitive impairment.
Angelman Syndrome↗
Behavioral phenotype of Smith-Magenis syndrome (del 17p11.2).
Smith-Magenis syndrome (SMS) is a distinct and clinically recognizable multiple congenital anomaly (MCA) and mental retardation syndrome caused by an interstitial deletion of chromosome 17 p11.2. The phenotype of SMS has been well described and includes: a characteristic pattern of physical features; a hoarse, deep voice; speech delay with or without associated hearing loss; signs of peripheral neuropathy; variable levels of mental retardation; and neurobehavioral problems. Although self-injury and sleep disturbance are major problems in SMS, studies are limited on the behavioral phenotype of SMS. This report reviews the current state of knowledge about SMS and presents new data based on syndrome-specific observations by the authors' longitudinal experience working with SMS, specifically related to the behavioral aspects of SMS. This information should have relevance for parents, clinicians, geneticists, and educators involved in the care of individuals with SMS.
Abnormalities, Multiple↗
Sleep disturbance in Smith-Magenis syndrome (del 17 p11.2).
Smith-Magenis syndrome (SMS) is a clinically recognizable multiple congenital anomaly and mental retardation syndrome caused by an interstitial deletion of chromosome 17 p11.2. Although the physical and molecular genetic features of SMS are increasingly well understood, work is more limited on SMS's behavioral phenotype, which includes self-injury, tantrums, and sleep disturbance. This study examines the sleep behaviors of 39 individuals with SMS, ranging in age from 1.6 to 32 years (mean = 10.5). Prominent sleep problems, seen in 65 to 100% of the sample, included difficulties falling asleep, shortened sleep cycles, frequent and prolonged nocturnal awakenings, excessive daytime sleepiness, daytime napping, snoring, and bed-wetting. Medication to facilitate sleep was used by 59% of SMS subjects. Possible etiologic mechanisms of sleep disturbance in SMS are discussed, as are recommended interventions.
Abnormalities, Multiple↗
Mental retardation: a review of the past 10 years. Part I.
OBJECTIVE: To review the literature over the past decade on mental retardation, particularly as regards its definition, prevalence, major causes, and associated mental disorders. METHOD: A computerized search was performed for articles published in the past decade, and selected papers were highlighted. RESULTS: The study of mental retardation has benefited considerably by advances in medicine generally and by developments in molecular neurobiology in particular. Increasing awareness of psychiatric comorbidity in the context of intellectual disability highlights the need for studies of the phenomenology and treatment of mental disorders in this population. CONCLUSIONS: Although the study of developmental disorders has advanced significantly over the past decade, considerable work remains. Mental retardation is a model for the utility of the biopsychosocial approach in medicine.
Adolescent↗
Mental retardation: a review of the past 10 years. Part II.
OBJECTIVE: To review the literature over the past decade on mental retardation, particularly with respect to genetics and behavioral phenotypes. METHOD: A computerized search was performed for articles published in the past decade, and selected papers were highlighted. RESULTS: The study of mental retardation has benefited considerably by advances in medicine generally, and by developments in molecular neurobiology in particular. These advances in genetics have led to new insights regarding the causes of mental retardation, as well as a growing appreciation of behavioral phenotypes associated with some mental retardation syndromes. CONCLUSIONS: Although the study of developmental disorders has advanced significantly over the past decade, considerable work remains. Mental retardation should remain the model for the utility of the biopsychosocial approach in medicine.
Adolescent↗
Trajectories and profiles of adaptive behavior in males with fragile X syndrome: multicenter studies.
We conducted two multicenter studies on adaptive trajectories and profiles in males with fragile X syndrome. Study 1 longitudinally assessed 29 males ages 1-20 years using age-equivalent scores from the Vineland Adaptive Behavior Scales. Fragile X boys ages 1-10 years showed significant gains in adaptive skills from first to second testing; males ages 11-20 years were stable in their adaptive development. Study 2 cross-sectionally examined 132 males ages 1-20 years. Significant age-related gains were found in boys ages 1-10, particularly in preschool children. Subjects ages 11-20 showed increased variability and nonsignificant relations between age and adaptive skills. Preliminary findings from 26 young adults with fragile X syndrome ages 21-40 years showed stable age-equivalent adaptive scores during these years. Relative strengths in daily living skills and weaknesses in communication were only evident among older subjects. Significant relations were found between adaptive behavior standard scores and IQ; these two scores also showed age-related declines that likely parallel one another. Findings are related to adaptive features in other genetic syndromes, and to directions for future adaptive behavior research.
Activities of Daily Living↗
Though disorder in high-functioning autistic adults.
Examined thought disorder in a sample (n = 11) of high-functioning autistic young adults and older adolescents (mean IQ = 83) utilizing objective ratings from the Thought, Language and Communication Disorder Scale (TLC Scale) and projective data from the Rorschach ink blots. Results from the TLC Scale pointed to negative features of thought disorder in this sample (e.g., Poverty of Speech). Rorschach protocols revealed poor reality testing and perceptual distortions in every autistic subject, and also identified several areas of cognitive slippage (e.g., Incongruous Combinations, Fabulized Combinations, Deviant Responses, Inappropriate Logic). Comparing TLC Scale and Rorschach results to schizophrenic reference groups, autistic subjects demonstrated significantly more Poverty of Speech and less Illogically on the TLC Scale, and on the Rorschach they evidenced features of thought disorder that are encountered also in schizophrenia. Results are discussed in relation to the measures employed, and to areas of similarity and difference between autism and schizophrenia.
Adolescent↗
Intellectual, academic, and adaptive functioning of Tourette syndrome children with and without attention deficit disorder.
The intellectual, academic, and adaptive strengths and weaknesses of 30, medication-free children (M = 10.5 years) with Tourette syndrome (TS) were assessed with a battery of standardized psychoeducational measures and the Vineland Adaptive Behavior Scales. Results indicated significant relative weaknesses in mental and written arithmetic, and relative strengths in reading achievement and abstract, logical thinking. Socialization skills emerged as a significant weakness in adaptive functioning. Comparisons between TS children with attention deficit disorder with hyperactivity (ADD-H) (n = 19) weakness in both groups in all areas assessed, but significantly lower performance IQs in TS subjects with ADD-H. These findings are discussed in relation to future research with TS children.
Achievement↗
Cognitive, behavioral, and adaptive functioning in fragile X and non-fragile X retarded men.
The cognitive, behavioral, and adaptive functioning of 12 men with fragile X syndrome (aged 23 to 62 years) was systematically assessed and compared to two matched groups of retarded men without fragile X syndrome residing at the same institution. The fragile X group was largely indistinguishable from the comparison groups on the cognitive, behavioral, and adaptive measures. Fragile X patients were, however, significantly more likely to have achieved levels of adaptive functioning commensurate with their intellectual abilities. Fragile X subjects who had similarly affected siblings emerged as significantly higher-functioning in all areas than Fragile X subjects who did not have affected siblings. These findings are discussed with respect to future research.
Adaptation, Psychological↗
An evaluation of the Autism Behavior Checklist.
The Autism Behavior Checklist (ABC), an assessment instrument for autistic individuals, was evaluated in a group of 157 subjects, 94 clinically autistic and 63 nonautistic. The two groups differed significantly in ratings of pathology. Both false positive and false negative diagnostic classifications were made when the results of the checklist were compared with clinical diagnosis. Effects of developmental level and age were observed. The ABC appears to have merit as a screening instrument, though results of the checklist alone cannot be taken as establishing a diagnosis of autism. Important issues of reliability and validity remain to be addressed.
Adolescent↗
A comparison of language characteristics of mentally retarded adults with fragile X syndrome and those with nonspecific mental retardation and autism.
Fragile X syndrome is a recently identified form of mental retardation that is associated with a chromosomal abnormality and inherited in an X-linked manner. Previous studies have suggested that distinctive speech and language characteristics are associated with the syndrome. Twelve adult male residents of an institution for the retarded (aged 23 to 51 years) were compared on a series of speech and language measures to 12 adult males with nonspecific forms of MR who were residents of the same institution and were matched on age and IQ. A second contrast group consisted of similarly matched autistic men. Results revealed that there were no significant differences among the groups' performance, with the exception of increased rates of echolalia in the autistic group. A nonsignificant trend toward poorer performance on expressive measures on the part of the fragile X group was noted. The implications of these findings for further research on the syndrome are discussed.
Adult↗
Fragile-X syndrome: variability of phenotypic expression.
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Female↗
The Draw-a-Person task in persons with mental retardation: what does it measure?
As a widely used, easy-to-administer, and nonthreatening task, the Draw-a-Person (DAP) holds particular promise as a nonverbal index of intelligence in persons with mental retardation. The DAPs of 108 adolescents and adults with mental retardation were reliably scored using Naglieri's cognitive and emotional disturbance scoring systems. Contrary to expectations, visual-motor skills emerged as the best predictor of DAP cognitive scores. Intelligence was correlated with DAP scores, but had considerably less predictive value than visual-motor skills. DAP emotional indicator scores were only modestly associated with social adaptation; even less support was found linking DAP emotional indicators to psychopathology. Findings point to considerable caution in using the DAP as an index of intelligence or as a screen for adjustment problems or specific psychopathology. Although related to intelligence, this popular task seems predominantly to measure visual-motor development in adults with mental retardation.
Adolescent↗