Biomedical subjects

Stephen R Schroeder

Publications and source records attributed to Stephen R Schroeder.

13 recordsLinked to original sources

PubMed2006

A crossover study of risperidone in children, adolescents and adults with mental retardation.

Risperidone has shown safety and efficacy for aggressive and destructive behaviors in short-term studies. This longer-duration study includes a broad sample. Forty subjects, aged 8-56 years (mean=22), all with mental retardation and 36 with autism spectrum disorders participated in this 22-week crossover study, with 24 weeks of open maintenance thereafter. Of 40 subjects, 23 (57.5%) responded fully (50% decrease in Aberrant Behavior Checklist-Community Irritability subscale score), while 35 subjects (87.5%) showed a 25% decrease. Gender, mood disorder, and antiseizure medications did not alter response. Increased appetite and weight gain were common. Low dose risperidone was effective for aggressive behavior in persons with MR. More long-term studies are needed, incorporating weight control interventions.

Adolescent↗

PubMed2005

A double-blind, placebo-controlled study of valproate for aggression in youth with pervasive developmental disorders.

OBJECTIVE: The aim of this study was to study valproate efficacy and safety for aggression in children and adolescents with pervasive developmental disorders (PDD). METHODS: In this prospective double-blind, placebo-controlled study, 30 subjects (20 boys, 10 girls) 6-20 years of age with PDD and significant aggression were randomized and received treatment with valproate (VPA) or placebo (PBO) for 8 weeks as outpatients. Mean VPA trough blood levels were 75.5 mcg/mL at week 4 and 77.8 mcg/mL at week 8. RESULTS: No treatment difference was observed statistically between VPA and PBO groups. The Aberrant Behavior Checklist--Community Scale (ABC-C) Irritability subscale was the primary outcome measure (p = 0.65), and CGI--Improvement (p = 0.16) and OAS (p = 0.96) were secondary outcome measures. Increased appetite and skin rash were significant side effects. Only 1 subject was dropped from the study owing to side effects, notably a spreading skin rash, which then resolved spontaneously. Two subjects receiving VPA developed increased serum ammonia levels, one with an associated parent report of slurred speech and mild cognitive slowing. Poststudy, of 16 VPA and PBO subjects receiving VPA, 10 subjects demonstrated sustained response, 4 of whom later attempted taper, with significant relapse of aggression. CONCLUSION: The present negative findings cannot be viewed as conclusive, partly owing to the large placebo response, subject heterogeneity, and size of the groups. Larger studies are needed to expand upon these findings.

Adolescent↗

PubMed2005

Risperidone-induced prolactin elevation in a prospective study of children, adolescents, and adults with mental retardation and pervasive developmental disorders.

OBJECTIVE: Risperidone is widely prescribed for aggression and self-injury in children, adolescents, and adults with mental retardation (MR) and pervasive developmental disorders (PDD). Risperidone elevates prolactin more than other atypical antipsychotic medications. Females may show greater prolactin elevation than males. METHOD: In this relatively long-term study of risperidone efficacy and safety for aggression and self-injury in children, adolescents, and adults with MR and PDDs, serum prolactin was measured in a 21-subject subset during the course of a double-blind, placebo-controlled trial. Prolactin was measured in ng/mL at baseline, once during acute treatment, and once during maintenance. RESULTS: In children and adolescents (n=10), mean age of 12.5 years, prolactin increased from mean 13.2+/-8.6 at baseline to 31.0+/-11.6 acutely and remained elevated at 37.9+/-10.4 in maintenance. In adults, mean age of 35.3 years, prolactin increased more markedly from 11.6+/-7.4 baseline (n=11) to 93.3+/-54.2 acutely but decreased to 67.8+/-62.9 in maintenance (n=7). Prolactin remained significantly elevated above normal in all subjects for at least 26 weeks. Mean prolactin of adult females, while similar to that of adult males at baseline, was 2.2 times male levels acutely and 3.7 times greater in maintenance. CONCLUSION: In this small subset, mean prolactin elevation persisted for at least 26 weeks. In adults, females showed significantly greater elevations than males.

Adolescent↗

PubMed2005

The overt aggression scale for rating aggression in outpatient youth with autistic disorder: preliminary findings.

Aggression is a common and costly problem in youth with developmental disabilities. Rating scales that accurately capture and measure subtypes of aggression phenomenology, frequency and severity are urgently needed, in both clinical practice and research. The authors studied the Overt Aggression Scale (OAS) in a preliminary sample of eight outpatients who participated in an ongoing placebo-controlled study of valproate for aggression in autism. Subjects' OAS aggression scores showed significant correlation with the already validated retrospectively rated Aberrant Behavior Checklist Community Scale irritability subscale. Further study of the OAS in outpatients with aggression and developmental disabilities is warranted.

Adolescent↗

PubMed2004

Effects of risperidone on destructive behavior of persons with developmental disabilities: III. Functional analysis.

Functional analyses were conducted during a double-blind, placebo-controlled study of the atypical antipsychotic medication risperidone with 13 individuals. Risperidone was effective in reducing destructive behavior (compared to placebo) for 10 participants. For 7 of these responders, an undifferentiated pattern of responding occurred across their baseline functional analysis conditions (i.e., a similar rate of responding across conditions), and risperidone treatment produced nonspecific reductions of their destructive behavior across functional analysis conditions. For the remaining 3 responders, a differentiated pattern of responding occurred across their baseline functional analysis conditions (i.e., an elevated rate of responding occurred in a specific condition), and risperidone treatment produced function-specific reductions of their destructive behavior.

Adult↗

PubMed2003

Use of functional analysis methodology in the evaluation of medication effects.

The atypical antipsychotic medication risperidone was evaluated using a double-blind, placebo-controlled design in the treatment of destructive behavior in two individuals with autism. Pre-medication functional analyses indicated that destructive behavior was maintained by escape from demands, attention, or access to tangible items. For both individuals, destructive behavior during the demand condition was significantly reduced during the medication phases, whereas destructive behavior continued to occur to obtain tangible items (Reggie) and attention (Sean). In addition, there appeared to be a differential effect of the medication on self-injurious behavior (SIB) versus aggression for Sean. Results of the study demonstrate how functional analysis may provide information on those conditions and behaviors that are most likely to be affected by a specific medication.

Adult↗

PubMed2003

Rate-decreasing effects of the atypical neuroleptic risperidone attenuated by conditions of reinforcement in a woman with mental retardation.

Effects of two doses of risperidone on the performance of a matching task under tangible reinforcement and nonreinforcement conditions were measured in a woman with mental retardation. In both conditions, time to complete the task increased and response rates decreased under two doses of risperidone. Accuracy was generally unchanged. These changes were much smaller in the tangible reinforcement condition; thus, reinforcement seemed to protect performance from the rate-decreasing effects of risperidone.

Adult↗

PubMed2002

Fixed ratio discrimination training increases in vivo striatal dopamine in neonatal 6-OHDA-lesioned rats.

Massed training in the conditional discrimination task, the fixed ratio discrimination (FRD) task led to elevated extracellular dopamine (DA) concentrations in the neonatal 6-hydroxydopamine (6-OHDA)-treated rat, a model of Lesch-Nyhan disease (LND). Rats neonatally treated with 6-OHDA or its vehicle were, as adults, implanted with microdialysis probes and assessed for basal pretraining concentrations of DA and its major metabolites. Subsequently, microdialysis samples were collected each day following three separate FRD training periods (trained group) or three separate periods of noncontingent food presentations (untrained group). The present study found that there were significant increases in extracellular DA in the caudate-putamen from basal pretraining concentrations in the repeated sample collections of trained 6-OHDA-lesioned animals but not in the samples of untrained 6-OHDA-lesioned animals. Consistent with previous studies [Brain Res. 508 (1990) 30.], there was an increase in the extracellular concentrations as compared to tissue concentrations of DA and 3,4-dihydroxyphenylacetic acid (DOPAC). Similar to our previous studies with long-term FRD training [Pharmacol. Biochem. Behav. 51 (1995) 861; Brain Res. 713 (1996) 246.], there was also an indication of an increase in cortical and striatal tissue concentration of DA in the trained 6-OHDA-lesioned animals as compared to the untrained 6-OHDA-lesioned animals. The elevations in striatal DA concentrations following operant performance in the present study illustrate how operant procedures of the behavior therapy used with individuals with LND and other mental retardation syndromes may interact with the modulation of dopaminergic function by the pharmaceutical application of DA antagonists to suppress aberrant behaviors.

Animals↗

PubMed2002

Multimodal evaluation of risperidone for destructive behavior: functional analysis, direct observations, rating scales, and psychiatric impressions.

Risperidone, an atypical neuroleptic, has become a popular option for treating destructive behaviors of persons with developmental disabilities. A few studies have been conducted that evaluate the effects of risperidone on destructive behavior; however, none of these studies have combined objective measures with rating scales to evaluate the effects of risperidone on destructive behavior across home and clinical settings. This study evaluated the wide range of effects of risperidone on destructive behavior of 2 persons with developmental disabilities using weekly functional analysis sessions, daily observations, hourly home data, weekly rating scales, and monthly psychiatric impressions. Results indicate that risperidone does decrease destructive behavior and that, for the most part, all of the various measures yielded similar results.

Adult↗

PubMed2002

Kinetic assessment of the effects of task difficulty, microencephaly, and a response manipulandum alteration on the rate of fixed-ratio discrimination acquisition.

Fixed-ratio discrimination (FRD) training session-accuracy curves were constructed using first-order, nonlinear regression and probit analyses to determine maximal (asymptotic) accuracy and the number of sessions required to reach half-maximal accuracy. Increased FRD difficulty (reductions in the differences between the 2 fixed-ratio values to be discriminated) and a training parameter change each increased the number of sessions required to reach half-maximal accuracy and decreased maximal FRD accuracy (i.e., session-accuracy curves were shifted down and to the right) regardless of analysis procedure. These findings indicate that the above manipulations induced mixed competitive-noncompetitive inhibition of the rate of FRD learning. Microencephalic rats were more sensitive to increases in FRD difficulty, whereas control rats were more sensitive to the training parameter change.

Animals↗

PubMed2002

Effects of risperidone on aberrant behavior in persons with developmental disabilities: II. Social validity measures.

Consumer satisfaction and social validity were measured during a double-blind, placebo-controlled evaluation of the atypical neuroleptic risperidone in treating severe aberrant behavior of persons with developmental disabilities. First, a satisfaction survey was completed after a medication trial by each participant's caregiver. Results showed that 100% of the caregivers felt that participation was a positive experience for themselves and participants. Second, 52 community members viewed videotapes of 5 participants during a clinical interview when they were taking either placebo or risperidone. Raters also indicated that when on the medication, participants displayed fewer aberrant behaviors, were less irritable, in a better mood, and were more responsive to their environment.

Adolescent↗

PubMed2002

A comparison of multiple reinforcer assessments to identify the function of maladaptive behavior.

Functional analysis results indicated that maladaptive behaviors displayed by a 25-year-old man with profound mental retardation were maintained by attention from caregivers and possibly, to a lesser degree, by access to tangible items. A concurrent-schedules procedure was then used to study the relative reinforcing value for maladaptive behavior of attention versus tangible items. Results of the concurrent-schedules assessment and subsequent functional communication training indicated that preference for attention versus access to a tangible object varied.

Adult↗

PubMedDate not supplied

Dopamine re-uptake inhibitor GBR-12909 induction of aberrant behaviors in animal models of dopamine dysfunction.

Many individuals with mental retardation exhibit chronic aberrant behaviors (CABs) that includes hyperactive, stereotyped, aggressive, and self-injurious behaviors. Brain imaging studies have found that several of these individuals have abnormalities in their dopaminergic neurotransmitter systems that are thought to be responsible in part, for the development of these behaviors. The present study evaluated the effects of a selective dopamine re-uptake blocker, GBR-12909 in three animal models of varying striatal dopamine concentrations. The three animal models included the neonatal 6-hydroxydopamine (6-OHDA)-lesioned rat, a model of dopamine neuronal depletion, the prenatal methylazoxymethanol (MAM)-exposed rat, a model of hyper-dopaminergic innervation and control rats, a model of normal dopaminergic function. The animals were given five daily injections of GBR-12909 and videotaped observations were conducted immediately following the injections and 6h later. The results of the study indicate that the MAM-treated rats exhibited more hyperactive behaviors than either the 6-OHDA or the control animals in response to the GBR-12909 injections. However, the 6-OHDA and control rats exhibited more self-injurious behaviors than the MAM rats. Interestingly, the topography of the self-injurious behavior exhibited differed from that we have previously observed in 6-OHDA lesioned rats following dopamine agonists and resembles the mouthing behaviors seen in some individuals with mental retardation, in particular those with Rett syndrome. These findings indicate the models of varying dopaminergic function interact differently with a dopamine re-uptake blocker than dopamine agonists and that the partially dopamine depleted model may model the behaviors seen in individuals with Rett syndrome.

Animals↗