I've heard that eating high sugar foods or ingesting large amounts of stimulants (caffeine, nicotine, etc) can worsen symptoms of ADHD. is this true? does the theory have any grounding in scientific research?
Yes they can and the scientific basis on it is simply that stimulants like caffeine and nicotine are just that: stimulants. they increase energy and blood flow, which would exacerbate the HYPERACTIVE portion of the ADHD quite easily.
They say it does, but I don't believe it.