Average MRI differences are generalized to large populations, not indivudals but may be essential for those with developmental disorders when there has been an injury or some sort of trauma. An MRI will not tell us if there is a specific developmental disorder. EEG's can be useful in determining the different processing speeds that may only be seen in those with developmental disorders.
With all medications we should be concerned about this. It is a valid concern for many parents and caregivers. Especially, with the substantial increase in the abuse of prescription drugs. Stimulant medication should only be used if there is evidence that the individual performs better on the medication. However, the risk of NOT treating a developmental disorder such as an attention disorder that may warrant stimulant medication puts an individudal at a much higher risk for substance abuse. It also increase risk of addiction to street narcotics. These risks can be lessened with safe, monitored daily prescriptions or other therapies. Those with a family history of substance abuse should be monitored carefully on such medications and evaluated on a regular basis.
We don't want to give kids medicine that they don't need, or would be harmful or won't work. We must be able to prove the medications effectiveness for the child specific need. We measure this through in office medication trials.