Does hair zinc predict amphetamine improvement of ADD/hyperactivity?

In 18 boys with ADHD (ages 6-12) in a balanced crossover design, parent and teacher hyperactivity rating differences between one month of dextroamphetamine and one month of placebo correlated significantly (p less than .05, 2 tailed) on Pearson's r with baseline hair zinc levels and nonsignificantly with 24-hour urinary zinc excretion. The signs of the correlations were such that a higher baseline zinc predicted a better placebo-controlled response to amphetamine.

Gamma-linolenic acid for attention-deficit hyperactivity disorder: placebo-controlled comparison to D-amphetamine.

In a Latin-square double-crossover with random assignment to sequence, 18 boys, aged 6-12 years, with attention-deficit hyperactivity disorder received 1 month each of placebo, D-amphetamine, and Efamol (evening primrose oil containing gamma-linolenic acid, with vitamin E as preservative). Parents' ratings were noncontributory. Teachers' ratings showed a trend of Efamol effect between placebo and D-amphetamine.