Stimulant
A substance that increases activity in the central nervous system, often raising alertness, energy, or attention.
Dopamine: A neurotransmitter involved in movement, motivation, reward learning, and attention. Many stimulants increase dopamine signaling, contributing to alertness and reinforcement.
Central nervous system: The brain and spinal cord, which process and coordinate information throughout the body. Stimulants are defined by increasing activity in this system.
Attention deficit hyperactivity disorder: A neurodevelopmental condition involving persistent inattention, hyperactivity, and impulsivity that impair functioning. Prescription stimulants can reduce core symptoms for many people with ADHD.
Depressant: A substance that reduces activity in the central nervous system. Depressants broadly oppose stimulants’ activating effects, though drug effects can overlap.
Stimulant use disorder: A pattern of stimulant use causing clinically significant impairment or distress. Repeated use of some stimulants can develop into compulsive use despite harm.
Norepinephrine: A neurotransmitter and hormone involved in arousal, attention, and stress responses. Increased norepinephrine signaling helps explain stimulants’ alerting effects.
Neurotransmitter: A chemical messenger that transmits signals between neurons or between neurons and other cells. Stimulant effects often arise by changing neurotransmitter release, reuptake, or receptor activity.
Methylphenidate: A prescription stimulant that inhibits dopamine and norepinephrine transporters. It is widely used to treat ADHD and narcolepsy.
Opioid: A substance that acts on opioid receptors to relieve pain and can cause euphoria and respiratory depression. Opioids primarily alter pain and reward pathways rather than producing stimulant-like activation.
Stimulant withdrawal: A set of symptoms following reduction or cessation after sustained stimulant use. Fatigue, low mood, and sleep changes can follow the end of heavy use.