A 16-week study appearing in the Journal of Child and Adolescent Psychopharmacology (2007; 17(6): 791-802) involved 112 children with ADHD and supplementation with acetyl-L-carnitine. The children were given either a placebo or the supplement; dosage was based on the child’s weight. Acetyl L-carnitine was found to be beneficial for the subjects with the inattentive type of ADHD, but was not beneficial for the children with the combined type of ADHD.

Another small study appearing in Prostaglandins, Leukotreines and Essential Fatty Acids (2002;67(1):33-38) involving 24 boys who received L-carnitine at a dosage of 100mg/kg of body weight. The boys were divided into two groups, one receiving the supplement. They were evaluated using the Child Behavior Checklist. The supplementation with L-carnitine reduced inattentiveness and aggressive behavior.

Both of these were small, pilot studies. They do, however, show some promise. L-carnitine promotes energy production by enhancing fat oxidation in the cell mitochondria.