The researchers accept many people believe the drugs do work for them, but argue that could be a placebo effect - people feel better simply because they are taking a medication which they think will help them.

BBC: RELATED BBC SITES

Patients will be asked to keep a record of the dose and how often they are taking the medication.

BBC: NEWS | Health | Warning to patients on toxic drug

Recent studies show clearly that when people believe they are taking an active medication but are receiving a placebo their brains activate in much the same way -- but to a lesser degree -- as their brains do in response to the active medication.

CNN: Do homeopathic treatments for ADHD work?