Grant: Master's Award: Canada Graduate Scholarships

Dopamine (DA), a neurotransmitter associated with motivated behaviour and cognition, is closely implicated in Attention Deficit Hyperactivity Disorder (ADHD). In fact, the most effective treatment against ADHD is stimulant drugs, such as methylphenidate (MPD; Ritalin), which increase DA function. However, ADHD sufferers must continually take their medication or the ADHD symptoms will quickly resurface. More troubling, chronic use of stimulants is known to create long-term changes in the brain and behaviour. For example, prolonged stimulant use makes the DA system more sensitive to stimulants and it increases the amount of movement caused by the drugs following their administration. Interestingly, exercise has been independently shown to be effective in reducing ADHD symptoms and to protect against long-term changes induced by various stimulants. However, researchers have not yet shown whether these positive effects of exercise extend to repeated MPD use. For this reason, this project will evaluate the protective role of exercise against behavioural changes in movement caused by MPD. To do so, male rats will receive different amounts of physical activity in the form of wheel running, before being repeatedly administered with clinically relevant doses of MPD or saline injections. After documenting the effect in rats, future brain imaging studies should be conducted to translate the findings to human participants. Ultimately, this project may provide health practitioners with early insight on an exercise appendix to stimulant treatment, which may guard against potential negative long-term changes caused by chronic ADHD medication.