This cross-sectional study reports that global differences in gray matter volume may be due to alterations in the general mechanisms underlying normal brain development in attention-deficit/hyperactivity disorder.
Recent work suggests that the amphetamine sensitization model of schizophrenia can safely be induced in healthy volunteers and is associated both with behavioral and dopaminergic hypersensitivity to amphetamine. However, the effects of a sensitization on brain function remain unclear.
To assess the impact of a sensitizing dosage regimen of dextroamphetamine on human cortical functioning and cognition.
Randomized, double-blind, parallel-groups design using pharmacological functional magnetic resonance imaging.
The neuroimaging research unit at the Institute of Psychiatry, King's College London, London, England.
Healthy male volunteers (n = 22).
Dextroamphetamine (20 mg) or placebo administration at 4 testing sessions, using a dosage regimen shown to induce sensitization (ie, 3 doses administered with a 48-hour interdose interval and a final dose after a 2-week washout period).
Sensitization was characterized by enhanced subjective response to the drug, changes in behavioral performance (reaction time and accuracy), and functional magnetic resonance imaging measurements of brain activity during an N-back working memory task.
Sensitization was associated with more rapid responding during the performance of an intermediate-load working memory challenge. During a high-load cognitive challenge, sensitization did not produce performance deficits, but functional magnetic resonance imaging showed hyperactivity of the dorsolateral prefrontal cortex and aberrant recruitment of the superior temporal gyrus, caudate nucleus, and thalamus. Furthermore, the change in striatal activity was negatively correlated with the enhanced subjective effects of the drug, whereas prefrontal hyperactivity was positively correlated with sensitized measures of alertness.
These transient load-dependent abnormalities of frontal and temporal activity induced by amphetamine sensitization support neuroimaging findings in schizophrenic patients, implying that amphetamine sensitization may help to bridge pathophysiological theories of schizophrenia that focus on pharmacological (dopaminergic) and cognitive mechanisms, respectively.
This laboratory-based cross-sectional study assesses cue-induced craving for cocaine in adults using both subjective and objective indices of cue-elicited responses.
This longitudinal prospective study uses data from the Nurses’ Health Study to examine the association between religious service attendance and suicide and the joint associations of suicide with service attendance and religious affiliation.
This cohort study examines whether quantified neural function in social perception circuits can serve as an individual-level marker of autism spectrum disorder in children and adolescents.
This meta-analysis of randomized and observational studies reports comparison of neonatal outcomes among women with untreated antenatal depression vs no depression.