Moderate doses: used to reduce anxiety; produce euphoria, makes you feel better, reduced stress levels. High doses: slow vital life processes, can be fatal in very high doses. Increases activity of gaba (inhibitory neurotransmitter anxiety reduction: decreases activity of glutamate (major excitatory neurotransmitter, co(cid:373)(cid:271)i(cid:374)atio(cid:374) (cid:272)reates (cid:862)high(cid:863) a(cid:374)d the(cid:374) (cid:862)dow(cid:374)(cid:863) phase. Increase blood pressure, heart rate, respiration, alertness: creates a pattern of: big high -> big low, everyday caffeine addictive/withdrawal. Increases activity of norepinephrine, dopamine by blocking reuptake: chronic use cognitive impairment, brain damage. Continuous heavy use can produce amphetamine psychosis. Opium = product of poppy plant opiates: morphine, codeine, heroin. Bind to receptors activated by endorphins: pain relief, mood changes, inducing euphoria. Highly addictive and traumatic withdrawal: withdrawal is extremely severe and painful due to how the drug binds with the system. Distort or intensify sensory experience: blur boundaries between fantasy and reality.