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Biomedical subjects

E M Dykens

Publications and source records attributed to E M Dykens.

At least 19 recordsLinked to original sources
PubMed2004

Sensorimotor gating abnormalities in young males with fragile X syndrome and Fmr1-knockout mice.

Fragile X syndrome (FXS) is the most common single gene (FMR1) disorder affecting cognitive and behavioral function in humans. This syndrome is characterized by a cluster of abnormalities including lower IQ, attention deficits, impairments in adaptive behavior and increased incidence of autism. Here, we show that young males with FXS have profound deficits in prepulse inhibition (PPI), a basic marker of sensorimotor gating that has been extensively studied in rodents. Importantly, the magnitude of the PPI impairments in the fragile X children predicted the severity of their IQ, attention, adaptive behavior and autistic phenotypes. Additionally, these measures were highly correlated with each other, suggesting that a shared mechanism underlies this complex phenotypic cluster. Studies in Fmr1-knockout mice also revealed sensorimotor gating and learning abnormalities. However, PPI and learning were enhanced rather than reduced in the mutants. Therefore, these data show that mutations of the FMR1 gene impact equivalent processes in both humans and mice. However, since these phenotypic changes are opposite in direction, they also suggest that murine compensatory mechanisms following loss of FMR1 function differ from those in humans.

Acoustic Stimulation↗
PubMed2002

Maladaptive behaviour in children and adolescents with Down's syndrome.

BACKGROUND: Although children with Down's syndrome (DS) are at lower risk for psychopathology than others with intellectual disability, they do show more problems than typically developing children. However, age-related trends in these problems remain unclear. METHODS: The present authors examined age-related changes in the maladaptive behaviours of 211 children and adolescents with DS aged between 4 and 19 years (mean = 9.74 years). Most participants (n = 180) were recruited from families residing in the greater Los Angeles area, California, USA, while a minority (n = 31) were patients from a clinic specializing in the psychiatric management of people with DS. The participants were divided into four age groups: (1) 4-6 years, (2) 7-9 years, (3) 10-13 years and (4) 14-19 years. RESULTS: Externalizing behaviours were lower across both the community and clinic samples, while internalizing behaviours were significantly higher in older adolescents aged between 14 and 19 years. Increases were found in withdrawal, seen in 63% of community-based adolescents, and 75% of clinic adolescents. CONCLUSIONS: Older adolescents with DS may show decreased externalizing symptoms and subtle increases in withdrawal. Possible relationships are discussed between these shifts and increased risks of later-onset depression and Alzheimer's disease in adults with DS.

Adolescent↗
PubMed2001

Double-blind, placebo-controlled study of amantadine hydrochloride in the treatment of children with autistic disorder.

OBJECTIVE: To test the hypothesis that amantadine hydrochloride is a safe and effective treatment for behavioral disturbances--for example, hyperactivity and irritability--in children with autism. METHOD: Thirty-nine subjects (intent to treat; 5-19 years old; IQ > 35) had autism diagnosed according to DSM-IV and ICD-10 criteria using the Autism Diagnostic Interview-Revised and the Autism Diagnostic Observation Schedule-Generic. The Aberrant Behavior Checklist-Community Version (ABC-CV) and Clinical Global Impressions (CGI) scale were used as outcome variables. After a 1-week, single-blind placebo run-in, patients received a single daily dose of amantadine (2.5 mg/kg per day) or placebo for the next week, and then bid dosing (5.0 mg/kg per day) for the subsequent 3 weeks. RESULTS: When assessed on the basis of parent-rated ABC-CV ratings of irritability and hyperactivity, the mean placebo response rate was 37% versus amantadine at 47% (not significant). However, in the amantadine-treated group there were statistically significant improvements in absolute changes in clinician-rated ABC-CVs for hyperactivity (amantadine -6.4 versus placebo -2.1; p = .046) and inappropriate speech (-1.9 versus 0.4; p = .008). CGI scale ratings were higher in the amantadine group: 53% improved versus 25% (p = .076). Amantadine was well tolerated. CONCLUSIONS: Parents did not report statistically significant behavioral change with amantadine. However, clinician-rated improvements in behavioral ratings following treatment with amantadine suggest that further studies with this or other drugs acting on the glutamatergic system are warranted. The design of these and similar drug trials in children with autistic disorder must take into account the possibility of a large placebo response.

Adolescent↗
PubMed2001

Strengthening behavioral research on genetic mental retardation syndromes.

In this article we examine the status of behavioral research on genetic mental retardation syndromes. Although surveys suggest increased interest in such research, the field continues to struggle with three methodological issues: (a) how to think about control or contrast groups, (b) the interplay of behavioral phenotypes with development and other factors relating to within-group variation, and (c) the efficacy of etiology-based interventions. For each issue, we discuss salient concerns and make suggestions for future work.

Humans↗
PubMed2001

Drawings by individuals with Williams syndrome: are people different from shapes?

Because it is unclear whether people with Williams syndrome produce drawings that are delayed or deviant, we examined these two possibilities in Draw a Person and figure copying tasks (VMI) in 28 persons with Williams syndrome, 28 with mixed etiologies, and 28 with Down syndrome. All human figures could be classified into discrete stages of drawing development, and in all groups, drawing tasks were significantly correlated with MA. Human figures from participants with Williams syndrome were no more deviant than their counterparts, nor did they show "local-global" differences. Draw a Person scores exceeded VMI scores in the Williams syndrome group, whereas the Down syndrome group showed relative strengths on both drawing tasks, and the mixed group had no profile. Developmental and phenotypic implications of findings are discussed.

Adolescent↗
PubMed2001

Research in mental retardation: toward an etiologic approach.

Over the past two decades, mental retardation research converges on three general themes: co-occurring mental retardation and psychopathology; families of offspring with mental retardation; and the developmental approach regarding behavioral sequences and profiles. Intertwined with each theme is a mounting body of research on genetic mental retardation syndromes. We first review recent progress in each of the three domains--psychopathology, families, and development--based on studies of groups with heterogenous or nonspecific mental retardation. We then show how new findings from specific genetic syndromes take this knowledge even further, as well as aid in the search for genetic, physiological, and environmental mechanisms associated with certain behaviors. We end the review by briefly summarizing our reasons for promoting an etiological approach to future mental retardation research, as well as by discussing methodological and other challenges.

Adolescent↗
PubMed2000

Contaminated and unusual food combinations: what do people with Prader-Willi syndrome choose?

Although hyperphagia is a salient feature of Prader-Willi syndrome, researchers have yet to move beyond food preference and taste studies to examine more troublesome food-seeking behaviors in this population (e.g., eating food from the trash, eating inappropriate or unpalatable food combinations). Visually based tasks were used to examine willingness to eat contaminated food and various odd food combinations in 50 adolescents and adults with Prader-Willi syndrome, 42 IQ-matched participants with mental retardation, and 50 control participants without mental retardation. Although participants with Prader-Willi syndrome showed understandings similar to those of control participants about the purpose and fate of food, they endorsed eating contaminated food as well as highly unusual edible and inedible food combinations. Findings suggest novel adjuncts to traditional dietary approaches in the Prader-Willi syndrome population. Implications are also discussed for future research on food ideation in this population.

Adolescent↗
PubMed2000

Psychopathology in children with intellectual disability.

Recent advances are reviewed in understanding the heightened prevalence of psychopathology and maladaptive behavior among children with intellectual disability. Researchers have traditionally emphasized measurement and prevalence issues, using either psychiatric assessments or rating scales to identify the prevalence of various problems in children with intellectual disability. Yet the time is ripe to shift directions, and identify more precisely why children are at increased risk for psychopathology to begin with. Although several "biopsycho-social" hypotheses are reviewed, a particularly promising line of work links psychopathology to genetic intellectual disability syndromes. Psychiatric vulnerabilities in several syndromes are reviewed, as are the advantages of phenotypic work for understanding psychopathology among children with intellectual disability more generally.

Adolescent↗
PubMed1999

No relationship between the size of the deletion and the level of developmental delay in cri-du-chat syndrome.

Molecular cytogenetic and developmental assessment was performed on 50 individuals with cri-du-chat syndrome. Fluorescent in situ hybridization analysis was used to confirm a terminal deletion karyotype and map more precisely the location of the deletion breakpoint. We identified terminal deletion breakpoints mapping from 5p15.2 to 5p13. Developmental assessment was performed using the Vineland Adaptive Behavior Scales test. Composite Vineland Scores ranged from 20-75. In general, the communication score was higher than the composite score. Comparison of the size of the deletion with the composite Vineland score, as well as the Vineland Communication score, demonstrated that there was no correlation between the size of the deletion and the level of developmental delay. These results demonstrate that patients with cri-du-chat syndrome show high variability in the level of developmental achievement.

Chromosome Deletion↗
PubMed1999

Clinical and behavioral characteristics in FG syndrome.

FG syndrome is a rare X-linked recessive form of mental retardation, first described by Opitz and Kaveggia in 1974. Based on over 50 reported cases, FG syndrome is associated with agenesis of the corpus callosum, minor facial anomalies (high, broad forehead with frontal cowlick, ocular hypertelorism, down-slanted palpebral fissures, and small cupped auricles), relative macrocephaly, broad thumbs and halluces, and prominent fetal fingertip pads. Affected individuals manifest neonatal hypotonia and severe constipation, which usually resolves during mid-childhood. The hypotonia with joint hyperlaxity evolves into spasticity with joint contractures in later life. Affability, hyperactivity, and excessive talkativeness are noted frequently in patients with FG syndrome. Recently, we described three additional families (six additional patients) with FG syndrome who support the localization of a gene for the FG syndrome in chromosome region Xq12-q21 [Graham JM Jr, Tackels D, Dibbern K, Superneau D, Rodgers C, Corning K, Schwartz CE. 1998. Am J Med Genet 80:145-156.]. Using these same families and one additional sporadic case of FG syndrome, we compared behavioral and personality characteristics of 6 FG boys with other boys with syndromic and nonsyndromic mental retardation: eight with Down syndrome, seven with Prader-Willi syndrome, eight with nonspecific mental retardation, and 13 with Williams syndrome. Using the Vineland Adaptive Behavior Scales, the Reiss Personality Profiles, and the Achenbach Child Behavior Checklist, parents were asked to characterize the behavior and personality of their boys from ages 4 to 10 years. When compared with Williams syndrome, the FG boys had fewer internalizing behaviors and were significantly less anxious and withdrawn but had similar socially oriented, attention-seeking behaviors. On the Reiss Profile, FG boys were also quite similar to Williams syndrome boys. On the Vineland Scales, FG boys demonstrated significant relative strengths in their socialization skills, consistent with their personality, tending to confirm previous descriptions of their personalities.

Abnormalities, Multiple↗
PubMed1999

Obsessive-compulsive symptoms in Prader-Willi and "Prader-Willi-Like" patients.

OBJECTIVE: To compare obsessive-compulsive (OC) symptoms in patients with Prader-Willi syndrome (PWS) and symptoms in a group of patients presenting with "Prader-Willi-like" features but without the genetic abnormalities associated with PWS. METHOD: 16 patients aged 4 through 20 years were evaluated in a clinic specializing in the assessment and management of behavioral and food-related problems in PWS. Eight patients were found to have key features of the syndrome but did not have a PWS genotype. These PWS-like subjects were matched to 8 clinic patients with a confirmed deletion of the PWS critical region of the paternally derived chromosome 15. All subjects were evaluated for obesity, IQ, food-related problems, maladaptive behaviors, and non-food-related OC symptoms. RESULTS: There were no differences between the 2 groups with respect to measures of obesity, IQ, food-related difficulties, or overall maladaptive behaviors. The PWS group showed significantly greater numbers of OC symptoms and greater symptom severity. CONCLUSIONS: Patients with PWS have elevated numbers of OC symptoms and significant symptom-related impairment which are not explained by developmental delay, food-related difficulties, or obesity. OC symptoms are part of a behavioral phenotype that accompanies deletions on the proximal long arm of chromosome 15 in PWS.

Adolescent↗
PubMed1999

Maladaptive behavior differences in Prader-Willi syndrome due to paternal deletion versus maternal uniparental disomy.

Maladaptive behavior was compared across 23 people with Prader-Willi syndrome due to paternal deletion to 23 age- and gender-matched subjects with maternal uniparental disomy. Controlling for the higher IQs of the uniparental disomy group, deleted cases showed significantly higher maladaptive ratings on the Child Behavior Checklist's Internalizing, Externalizing, and Total domains as well as more symptom-related distress on the Yale-Brown Obsessive-Compulsive Scale. Across both measures, deleted cases were more apt to skin-pick, bite their nails, hoard, overeat, sulk, and withdraw. A dampening of symptom severity is suggested in Prader-Willi syndrome cases due to maternal uniparental disomy. Findings are compared to Angelman syndrome, and possible genetic mechanisms are discussed, as are implications for Prader-Willi syndrome and obsessive-compulsive behaviors.

Adolescent↗
PubMed1999

Refining behavioral phenotypes: personality-motivation in Williams and Prader-Willi syndromes.

Despite behavioral differences, individuals with Williams or Prader-Willi syndrome share a proneness to certain personality characteristics. We hypothesized that there are qualitative differences in these shared personality features. Personality-motivation (measured using the Reiss Profiles) was compared for equal numbers of age- and gender-matched individuals with Williams or Prader-Willi syndrome or mental retardation due to nonspecific causes. Each syndrome featured aberrant motivational profiles, and similarities were found across groups in various domains. Significant differences emerged in the specific stimuli that motivated behavior in several Reiss Profile domains. Implications are discussed for the "classic" sociable personality in Williams syndrome and for compulsivity in Prader-Willi syndrome. Recommendations are made for treatment and more refined phenotypic research.

Adolescent↗
PubMed1998

Distinctiveness and correlates of maladaptive behaviour in children and adolescents with Smith-Magenis syndrome.

This two-part study examines the distinctiveness and correlates of maladaptive behaviour in 35 children and adolescents with Smith-Magenis syndrome, a developmental disorder caused by an interstitial deletion of chromosome 17 (p11.2). Study I compares Child Behavior Checklist scores in 35 children with Smith-Magenis syndrome to age- and gender-matched subjects with Prader-Willi syndrome and mixed intellectual disability. Subjects with Smith-Magenis syndrome had significantly higher levels of maladaptive behaviour than the other groups. Although some problems were shared across groups, 12 behaviours differentiated the three groups with 100% accuracy. Study 2 assessed the frequency and correlates of self-injurious and stereotypical behaviours, including unusual features such as nail-yanking, inserting objects into bodily orifices, self-hugging and a 'lick-and flip' behaviour. Nail-yanking and bodily insertions were less common than other types of self-injury, and self-hugs and the 'lick-and flip' stereotypies were seen in about half the sample. Although age and degree of delay were correlated with problem behaviours, sleep disturbance emerged as the strongest predictor of maladaptive behaviour. The implications are discussed for clinical diagnostic ambiguities between the Smith-Magenis and Prader-Willi syndromes, and for intervention.

Adolescent↗
PubMed1998

Exercise and sports in children and adolescents with developmental disabilities. Positive physical and psychosocial effects.

This article reviews findings to date on the effects of exercise and sports in children and adolescents with developmental disabilities. Although much work remains, exercise and sports are associated with reduced maladaptive behavior in children with disabilities, as well as with improved physical fitness, self-esteem, and social competence. Improved physical and psychosocial functioning are found in studies of both children and adults with mental retardation, as well as in research on athletes enrolled in Special Olympics International, the largest recreational sport program in the world for persons with developmental disabilities. The review ends with recommendations for promoting recreation and sports in children and adolescents with disabilities.

Adolescent↗