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Cerebellar morphology and the effects of stimulant medications in youths with attention deficit-hyperactivity disorder.

ABSTRACT: The cerebellum is emerging as a key anatomical structure underlying normal attentional and cognitive control mechanisms. Dysregulation within cerebellar circuits may contribute to the core symptoms of Attention Deficit/Hyperactivity Disorder (ADHD). In the present study we aimed to characterize surface morphological features of the cerebellum in ADHD and healthy comparison youths. Further, we studied the association of cerebellar morphology with the severity of ADHD symptoms and the effects of stimulant treatment. We examined 46 youths with ADHD and 59 comparison youths 8-18 years of age in a cross-sectional, case-control study using magnetic resonance imaging. Measures of cerebellar surface morphology were the primary outcome. Relative to comparison participants, youths with ADHD exhibited smaller regional volumes corresponding to the lateral surface of the left anterior and the right posterior cerebellar hemispheres. Stimulant medication was associated with larger regional volumes over the left cerebellar surface, whereas more severe ADHD symptoms were associated with smaller regional volumes in the vermis. We used optimized measures of morphology to detect alterations in cerebellar anatomy specific to ADHD, dimensions of symptomology, and stimulant treatment. Duration of treatment correlated positively with volumes of specific cerebellar subregions, supporting a model whereby compensatory morphological changes support the effects of stimulant treatment.

SUBMITTER: Ivanov I

PROVIDER: S-EPMC3895250 | biostudies-literature | 2014 Feb

REPOSITORIES: biostudies-literature

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Cerebellar morphology and the effects of stimulant medications in youths with attention deficit-hyperactivity disorder.

Ivanov Iliyan I Murrough James W JW Bansal Ravi R Hao Xuejun X Peterson Bradley S BS

Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology 20130927 3

The cerebellum is emerging as a key anatomical structure underlying normal attentional and cognitive control mechanisms. Dysregulation within cerebellar circuits may contribute to the core symptoms of Attention Deficit/Hyperactivity Disorder (ADHD). In the present study we aimed to characterize surface morphological features of the cerebellum in ADHD and healthy comparison youths. Further, we studied the association of cerebellar morphology with the severity of ADHD symptoms and the effects of s ...[more]

PMID: 24077064

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Project description:ImportanceSignificant concern exists over treating youths with attention-deficit/hyperactivity disorder (ADHD) with antipsychotic medications, yet little is known about the factors associated with antipsychotic treatment.ObjectivesTo describe the percentage of youths who fill antipsychotic prescriptions in the year following a new diagnosis of ADHD and characterize the clinical and demographic factors associated with antipsychotic initiation.Design, setting, and participantsA retrospective longitudinal cohort analysis of antipsychotic treatment was performed in 187 563 youths, aged 3 to 24 years, with a new diagnosis of ADHD (without recent diagnosis of any US Food and Drug Administration [FDA]-indicated conditions for antipsychotic treatment). The sample was derived from the 2010 to 2015 MarketScan Commercial Database, with the analysis completed between November 1, 2018, and May 30, 2019.Main outcomes and measuresThe percentage of youths prescribed an antipsychotic in the first year following a new diagnosis of ADHD. Among those prescribed antipsychotic medications, the percentage who received a diagnosis of conduct disorder, oppositional defiant disorder, or a disorder for which 1 or more antipsychotic medication has received an indication for use in youths from the FDA (schizophrenia, bipolar disorder, and Tourette disorder) and the percentage that filled an antipsychotic prescription before filling a stimulant prescription (methylphenidate or amphetamine derivative).ResultsOf the 187 563 youths included in the study, 114 305 (60.9%) were male with a mean (SD) age of 13.74 (5.61) years. In the year following a new ADHD diagnosis, 4869 youths (2.6%; 95% CI, 2.5%-2.7%) with ADHD were prescribed an antipsychotic. Youths treated with antipsychotics with ADHD were more likely than their peers who were not receiving an antipsychotic to have recently received diagnoses of self-harm and/or suicidal ideation (adjusted odds ratio [aOR], 7.5; 95% CI, 5.9-9.6), oppositional defiant disorder (aOR, 4.4; 95% CI, 3.9-4.9), and substance use disorder (aOR, 4.0; 95% CI, 3.6-4.5). The youths who received antipsychotics were also more likely to have received inpatient treatment (aOR, 7.9; 95% CI, 6.7-9.3). During the year following the new ADHD diagnosis, 52.7% (95% CI, 51.3%-54.1%) of youths treated with antipsychotics received a diagnosis for which antipsychotics have either an FDA or evidence-supported indication for their use. Among youths who initiated antipsychotic medications, 47.9% (95% CI, 46.5%-49.3%) did not receive a stimulant prescription between their ADHD diagnosis and antipsychotic initiation. Antipsychotic prescribing was proportionally highest for preschool-aged children (4.3%) and associated with neurodevelopmental disorders (aOR, 3.9; 95% CI, 1.3-11.2) and recent inpatient mental health treatment (aOR, 8.9; 95% CI, 1.7-45.8).Conclusions and relevanceApproximately half of youths with a new ADHD diagnosis may have an evidence-supported indication for an antipsychotic medication. Less than half of these youths received a stimulant; the evidence-supported first line treatment for ADHD, before the antipsychotic was initiated. Use of antipsychotic prescribing appears to be associated with high levels of psychiatric comorbidity.

Project description:IntroductionAttention-deficit hyperactive disorder (ADHD) is the most common neurodevelopmental disorder in children. Diagnosis is currently based on behavioral criteria, but magnetic resonance imaging (MRI) of the brain is increasingly used in ADHD research. To date however, MRI studies have provided mixed results in ADHD patients, particularly with respect to the laterality of findings.MethodsWe studied 849 children and adolescents (ages 6-21?y.o.) diagnosed with ADHD (n?=?341) and age-matched typically developing (TD) controls with structural brain MRI. We calculated volumetric measures from 34 cortical and 14 non-cortical brain regions per hemisphere, and detailed shape morphometry of subcortical nuclei. Diffusion tensor imaging (DTI) data were collected for a subset of 104 subjects; from these, we calculated mean diffusivity and fractional anisotropy of white matter tracts. Group comparisons were made for within-hemisphere (right/left) and between hemisphere asymmetry indices (AI) for each measure.ResultsDTI mean diffusivity AI group differences were significant in cingulum, inferior and superior longitudinal fasciculus, and cortico-spinal tracts (p?<?0.001) with the effect of stimulant treatment tending to reduce these patterns of asymmetry differences. Gray matter volumes were more asymmetric in medication free ADHD individuals compared to TD in twelve cortical regions and two non-cortical volumes studied (p?<?0.05). Morphometric analyses revealed that caudate, hippocampus, thalamus, and amygdala were more asymmetric (p?<?0.0001) in ADHD individuals compared to TD, and that asymmetry differences were more significant than lateralized comparisons.ConclusionsBrain asymmetry measures allow each individual to serve as their own control, diminishing variability between individuals and when pooling data across sites. Asymmetry group differences were more significant than lateralized comparisons between ADHD and TD subjects across morphometric, volumetric, and DTI comparisons.

Project description:Working memory impairments are commonly found in attention-deficit/hyperactivity disorder (ADHD) and often improve with psychostimulant treatment. Little is known about how these medications affect the function of frontoparietal brain regions engaged for working memory. This study used functional magnetic resonance imaging (fMRI) to examine medication-related changes in brain activation and functional connectivity in ADHD.Eighteen ADHD-combined subtype youths (ages 11-17) twice completed a Sternberg working memory fMRI task in a randomized, double-blind, placebo-controlled design. Medications were individualized as patients' standard, clinically effective psychostimulant (e.g., methylphenidate or dextroamphetamine/amphetamine combination) dose. Brain activity and functional connectivity were characterized using group independent component analysis. SPM5 repeated-measures t tests compared ADHD patients' network engagement and regional functional connectivity on and off medication.Independent component analysis identified six frontoparietal networks/components with hemodynamic responses to encoding/maintenance or retrieval phases of the Sternberg fMRI task. On medication, three of these networks significantly increased activation. Functional connectivity analyses found medication led to recruitment of additional brain regions that were not engaged into the networks when participants were on placebo. Also, medication strengthened connectivity of some frontoparietal regions. Many connectivity changes were directly related to improved working memory reaction time. Overall, there was strong evidence for regional functional connectivity changes following medication in structures previously implicated as abnormal in ADHD, such as anterior cingulate, ventrolateral prefrontal cortex, and precuneus.Stimulant medication has widespread effects on the functional connectivity of frontoparietal brain networks, which might be a mechanism that underlies their beneficial effects on working memory performance.

Project description:ObjectivePsychostimulants are partially effective in reducing cognitive dysfunction associated with attention-deficit/hyperactivity disorder (ADHD). Cognitive effects of guanfacine, an alternative treatment, are poorly understood. Given its distinct action on α2A receptors, guanfacine may have different or complementary effects relative to stimulants. This study tested stimulant and guanfacine monotherapies relative to combined treatment on cognitive functions important in ADHD.MethodChildren with ADHD (n = 182; aged 7-14 years) completed an 8-week, double blind, randomized, controlled trial with 3 arms: d-methylphenidate (DMPH), guanfacine (GUAN), or combination treatment with DMPH and GUAN (COMB). A nonclinical comparison group (n = 93) had baseline testing, and a subset was retested 8 weeks later (n = 38). Analyses examined treatment effects in 4 cognitive domains (working memory, response inhibition, reaction time, and reaction time variability) constructed from 20 variables.ResultsThe ADHD group showed impaired working memory relative to the nonclinical comparison group (effect size = -0.53 SD unit). The treatments differed in effects on working memory but not other cognitive domains. Combination treatment improved working memory more than GUAN but was not significantly better than DMPH alone. Treatment did not fully normalize the initial deficit in ADHD relative to the comparison group.ConclusionCombined treatment with DMPH and GUAN yielded greater improvements in working memory than placebo or GUAN alone, but the combined treatment was not superior to DMPH alone and did not extend to other cognitive domains. Although GUAN may be a useful add-on treatment to psychostimulants, additional strategies appear to be necessary to achieve normalization of cognitive function in ADHD.Clinical trial registration informationSingle Versus Combination Medication Treatment for Children With Attention Deficit Hyperactivity Disorder; http://clinicaltrials.gov/; NCT00429273.

Project description:ObjectiveBecause models of attention-deficit/hyperactivity disorder (ADHD) therapeutics emphasize benefits of both enhanced dopaminergic and noradrenergic signaling, strategies to enhance D1 and α2A agonism may yield enhanced clinical and cognitive responses. This study tested the hypothesis that combined effects of a dopamine and noradrenergic agonist, d-methylphenidate extended-release (DMPH) with guanfacine (GUAN), an α2A receptor agonist, would be clinically superior to either monotherapy and would have equal tolerability.MethodAn 8-week, double-blind, 3-arm, comparative trial randomized 7- to 14-year-olds with DSM-IV ADHD to GUAN (1-3 mg/day), DMPH (5-20 mg/day), or a combination (COMB) with fixed-flexible dosing. Outcome measures were the ADHD Rating Scale IV (ADHD-RS-IV) and the Clinical Global Impression-Improvement (CGI-I) scale. Data on adverse events and safety measures were obtained.ResultsA total of 207 participants were randomized and received drug. Analyses showed significant treatment group main effects for ADHD-RS-IV ADHD total (p = .0001) and inattentive symptoms (p = .0001). COMB demonstrated small but consistently greater reductions in ADHD-RS-IV Inattentive subscale scores versus monotherapies (DMPH: p = .05; f(2) = .02; and GUAN: p = .02; f(2) = .02), and was associated with a greater positive response rate by CGI-I (p = .01). No serious cardiovascular events occurred. Sedation, somnolence, lethargy, and fatigue were greater in both guanfacine groups. All treatments were well tolerated.ConclusionCOMB showed consistent evidence of clinical benefits over monotherapies, possibly reflecting advantages of greater combined dopaminergic and α2A agonism. Adverse events were generally mild to moderate, and COMB treatment showed no differences in safety or tolerability.Clinical trial registration informationSingle Versus Combination Medication Treatment for Children With Attention Deficit Hyperactivity Disorder (Project1); http://clinicaltrials.gov/; NCT00429273.

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Cerebellar morphology and the effects of stimulant medications in youths with attention deficit-hyperactivity disorder.

Publications

Cerebellar morphology and the effects of stimulant medications in youths with attention deficit-hyperactivity disorder.

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