 The effects of psychostimulants include increases in heart rate, body temperature, and sweating; improvements in alertness, attention, and endurance; increases in pleasure produced by rewarding events; but at higher doses agitation, anxiety, or even loss of contact with reality.Drugs in this group can have a high addiction potential, due to their activating effects on the dopamine-mediated reward system in the brain.However some can also be useful, at lower doses, for treating attention deficit hyperactivity disorder (ADHD) and narcolepsy.