Behavioral responses to 0.3 mg/kg i.v. d-amphetamine were studied in a series of 13 monozygotic twin pairs, using a double-blind randomized crossover design of active drug and placebo injections. Two independent behavioral responses which we termed "excitation" and "elation" were concordant in twin pairs And reproducible within individuals. Elation was correlated with plasma amphetamine levels, but excitation was not. Higher excitation was predicted by male sex, lower pre-drug plasma prolactin, and higher pre-drug total plasma MHPG. Growth hormone response after amphetamine was greater in persons with higher excitation scores. All the biological measures but pre-drug prolactin were concordant in twin pairs. These data may imply higher activity of norepinephrine and dopamine in persons with high excitation response. Neurochemical differences between the sexes are also implied.
|Original language||English (US)|
|Number of pages||9|
|Journal||Advances in the Biosciences|
|State||Published - Dec 1 1981|
- human monozygotic twins