Blockade of striatal dopamine transporters by intravenous methylphenidate is not sufficient to induce self-reports of "high." J Pharmacol Exp Ther 1999 Jan

The reinforcing effects of cocaine and methylphenidate have been linked to their ability to block dopamine transporters (DAT), however DAT blockade alone is not sufficient, and may be an explanation why Ritalin is not addicting and cocaine is.

Effects of methylphenidate on complex cognitive processing in ADHD. J Abnorm Psychol 1999 Feb

Without medication, children with ADHD showed high error rates and slow reaction times across both low and high task and concentration loads, as did younger, normal control children. On low stress tasks, methylphenidate at all doses helped ADHD children to improve accuracy with no loss in reaction time. At higher task loads, higher methylphenidate doses improved error rates while slowing reaction time. It is argued that methylphenidate improves self-regulatory ability, enabling children with ADHD to adapt differentially to high and low loads.

Long-term methylphenidate therapy in children with comorbid ADHD and chronic multiple tic disorder. Arch Gen Psychiatry 1999

Long term treatment with methylphenidate seems to be safe and effective for the management of ADHD behaviors in many children with mild to moderate tic disorder. Sometimes methylphenidate may exacerbate tics.

A comparison of Ritalin and Adderall: efficacy and time-course in children with ADHD. Pediatrics 1999 Apr;103(4):e43

Both drugs were routinely superior to placebo and produced dramatic improvements in rates of bad behavior, academic productivity, and staff/parent ratings of behavior. The doses of Adderall that were assessed produced greater improvement than did the assessed doses of Ritalin, particularly the lower dose of Ritalin, on numerous but not all measures. Adderall was more potent. Adderall was generally superior to the low dose of Ritalin when the effects of Ritalin were wearing off at midday and late afternoon/early evening. The lower dose (7.5mg) of Adderall produced effects comparable to those of the higher dose of Ritalin (17.5). Both drugs produced low and comparable levels of clinically significant side effects. Staff members preferred Adderall 3:1. 25% did not get benefits.

Methylphenidate treatment for bulimia nervosa associated with a cluster B personality disorder. Int J Eat Disorders 1999 Mar (Menninger Clinic)

Those with bulimia and a comorbid cluster B impulsive problem improved who had responded to psychotherapy and SSRI’s improved with methylphenidate with decreased bingeing and purging. (Note: very small study, and in my experience the BPD and ADHD are comorbid conditions - improving the attention deficit disorder improved their other problems since everything one has wrong makes everything else worse.)

Association of methylphenidate induced craving with changes in right striato-orbitofrontal metabolism in cocaine abusers: implications in addition. Am J Psychiatry 1999 Jan

Cravings in drug addicts in right side of brain.