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:
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
Apr 2010-Apr 2011 Trent Language and Cognition Lab