N&PD Moderators: Skorpio
Dopamine depletion does not alter the mood elevating effects of amphetamine
The subjects in the experimental arm of the OP were not "healthy men"; they were malnourished. It's not far-fetched to think that dietary depletion of certain essential AAs elicits a signaling cascade that shifts an organism's focus from leisure to survival. Reward cues would be less relevant (and therefore less salient) to the mind of one so preoccupied.
