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Baseline-dependent effects of amphetamine on attention are associated with striatal dopamine metabolism.

ABSTRACT: Psychostimulants, such as amphetamine, are widely used to treat attentional deficits. In humans, response to dopaminergic medications is complex with improvement often dependent on baseline performance. Our goal was to determine if attention in rats could be improved by low dose amphetamine in a baseline-dependent manner by examining the relationship between task performance, drug response and monoamine levels in corticostriatal tissue. Firstly, rats performed a signal detection task with varying signal durations before administration of saline, 0.1 or 0.25?mg/kg amphetamine. Following 0.1?mg/kg amphetamine, accuracy in poor performing individuals increased to that of high performing rats. Furthermore, baseline accuracy correlated with the magnitude of improvement after amphetamine. Secondly, neurochemical analysis of monoamine content and gene expression levels in the prefrontal cortex (PFC) and dorsal striatum (CPU) was conducted. CPU homovanillic acid and 5-hydroxyindoleacetic acid levels were increased in poor performers with a significant correlation between the expression of the dopamine transporter gene and baseline accuracy. No changes were found in the PFC. These results indicated poor performance was associated with greater response to amphetamine and altered DA and 5-HT neurotransmitter systems in CPU. These results suggest striatal monoamine function may be fundamental to explaining individual differences in psychostimulant response.

SUBMITTER: Turner KM

PROVIDER: S-EPMC5428442 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

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Baseline-dependent effects of amphetamine on attention are associated with striatal dopamine metabolism.

Turner Karly M KM Peak James J Burne Thomas H J TH

Scientific reports 20170322 1

Psychostimulants, such as amphetamine, are widely used to treat attentional deficits. In humans, response to dopaminergic medications is complex with improvement often dependent on baseline performance. Our goal was to determine if attention in rats could be improved by low dose amphetamine in a baseline-dependent manner by examining the relationship between task performance, drug response and monoamine levels in corticostriatal tissue. Firstly, rats performed a signal detection task with varyin ...[more]

PMID: 28331177

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Project description:ObjectiveSleep problems are common in adults with attention-deficit/hyperactivity disorder (ADHD). The presence of sleep problems at the time of presentation for ADHD treatment could impact the level of improvement in ADHD symptoms or executive function occurring with ADHD pharmacotherapy. Therefore, we examined the influence of baseline sleep quality on the effects of SHP465 mixed amphetamine salts (MAS) extended-release.MethodsAdults (18-55 years) with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision-defined ADHD and baseline ADHD Rating Scale IV (ADHD-RS-IV) total scores ≥ 24 were randomized to once-daily SHP465 MAS (12.5-75 mg) or placebo in a 7-week, double-blind, dose-optimization study. Post-hoc analyses evaluated SHP465 MAS treatment effects on ADHD symptoms, using the ADHD-RS-IV, and executive function, using the Brown Attention-Deficit Disorder Scale (BADDS), based on baseline sleep quality as defined by Pittsburgh Sleep Quality Index (PSQI) scores [sleep quality impaired (PSQI total score > 5; PSQI component scores 2 or 3) versus not impaired (PSQI total score ≤ 5; PSQI component scores 0 or 1)]. Analyses were conducted in the intent-to-treat population.ResultsOf 280 enrolled participants, 272 were randomized (placebo, n = 135; SHP465 MAS, n = 137). The intent-to-treat population consisted of 268 participants (placebo, n = 132; SHP465 MAS, n = 136), and 170 participants (placebo, n = 76; SHP465 MAS, n = 94) completed the study. Treatment differences nominally favored SHP465 MAS over placebo in both sleep impairment groups regarding ADHD-RS-IV total score changes (all nominal p < 0.05), except for those with impairment defined by sleep efficiency (p = 0.2696), and regarding BADDS total score changes (all nominal p < 0.05), except for those with impairment defined by sleep duration (p = 0.1332) and sleep efficiency (p = 0.8226). There were no statistically significant differences in SHP465 MAS treatment effects between sleep impairment groups.ConclusionsImprovements in ADHD symptoms and executive function occurred with dose-optimized SHP465 MAS, regardless of baseline impairment in some aspects of sleep in adults with ADHD, with no significant differences observed as a function of sleep impairment.Clinical trials registrationClinicalTrials.gov identifier-NCT00150579.

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Baseline-dependent effects of amphetamine on attention are associated with striatal dopamine metabolism.

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Baseline-dependent effects of amphetamine on attention are associated with striatal dopamine metabolism.

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