Research
About My Research
Attention-Deficit / Hyperactivity Disorder (ADHD) is
characterised by hyperactivity, impulsivity, and deficits in executive
functions (EFs). EFs, which are associated with a brain area called prefrontal
cortex (PFC), include abilities like attention, self-control, reasoning, and
problem-solving. Our brain cells communicate with each other via
neurotransmitters. In ADHD, there are lower levels of the neurotransmitter
dopamine (DA). Psychostimulants (or stimulants) are often used as treatment as
they increase DA. Some 50% of children with ADHD are now medicated with
stimulants. Yet, they often struggle in school. At moderate-to-high doses,
stimulants block DA’s transporters. The striatum (a brain region associated
with behavioural problems in ADHD) relies on that mechanism but PFC does not.
Thus at those doses, stimulants should help the striatum function better, but
not PFC. Recent animal neuroscience studies have now shown that at low doses,
stimulants specifically help PFC. Given this, we reasoned that psychiatrists
prescribing the right dose to help behaviour in ADHD might be giving too high a
dose to help cognition. We just completed a triple-blind study where each youth
with ADHD was tested once on their prescribed dose, and once on half that.
Whether the full dose was given in the 1st or 2nd session was randomised.
Regardless of whether the full dose was given in the 1st or 2nd session, all
performed better on EF tasks when on half their dose. For my dissertation I
would like to test the neural mechanism underlying this hypothesis. Using fMRI,
I aim to show in youths with ADHD that at moderately high stimulant doses, the
striatum works more efficiently and performance on a striatum-dependent task is
better, while at a low dose, PFC works more efficiently and performance on a
classic EF test is better. This is vital as understanding how the brain works
on different stimulant doses could help us change the standard of care for
ADHD, improving millions of lives.
Previous Lab Affiliations:
Research Assistant
Jan 2009-Apr 2011 Parent-Child Mother Goose study at Kawartha-Haliburton Children’s Aid Society
Nov 2010-Apr 2011 Trent Business Administration Program
Jan 2010-Apr 2010 Trent Action Cognition Lab
Apr 2009-Apr 2010 Trent Brain, Memory and Emotion Lab
Research Assistant/Transcriptionist
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