Claim: Levoamphetamine increases concentration.
Evidence: Levoamphetamine , also known as levamfetamine -LRB- INN -RRB- , -LRB- R -RRB- - amphetamine , - amphetamine , and L-amphetamine , is a central nervous system -LRB- CNS -RRB- stimulant known to increase wakefulness and concentration in association with decreased appetite and fatigue.