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Hemispheric processing and methylphenidate effects in attention-deficit hyperactivity disorder
M A Malone1, J R Kershner, J M Swanson
1Division of Neurology, Hospital For Sick Children, Toronto, Ontario, Canada.
Journal of Child Neurology
|April 1, 1994
Summary
Attention-deficit hyperactivity disorder (ADHD) may stem from neurotransmitter imbalances and bihemispheric dysfunction. ADHD medications may help by restoring neurotransmitter balance and improving attentional resource allocation between brain hemispheres.
Area of Science:
- Neuroscience
- Psychiatry
- Neurochemistry
Background:
- Attention-deficit hyperactivity disorder (ADHD) is associated with neurotransmitter imbalances.
- An asymmetric neural control system links dopaminergic pathways to left-hemispheric and noradrenergic pathways to right-hemispheric processing.
Purpose of the Study:
- To explore the roles of norepinephrine and dopamine imbalances in ADHD.
- To investigate the link between hemispheric processing and ADHD pathophysiology.
- To understand the mechanism of action for ADHD medications.
Main Methods:
- Review of existing evidence on neurotransmitter systems in ADHD.
- Analysis of the asymmetric neural control system model.
- Hypothesizing medication effects based on neurochemical and hemispheric interactions.
Main Results:
- ADHD may involve bihemispheric dysfunction with reduced dopaminergic and excessive noradrenergic functioning.
- Medication effects may be linked to restoring neurotransmitter balance.
- Medications may enhance control over attentional resource allocation between hemispheres.
Conclusions:
- ADHD pathophysiology may involve a complex interplay of neurotransmitter imbalances and hemispheric dysfunction.
- Medication efficacy in ADHD may be explained by the restoration of neurochemical balance and improved interhemispheric attentional control.