• ALL three of these stimulate the brain's "reward circuits"

• Cocaine is the most widespread drug in the world; however, the aforementioned drugs can be found in numerous places around the world
• Over half of addicts begin by consuming marijuana

• PCP- Veterinary anesthetic
• Cannabis- reduces nausea from chemotherapy

• morphine- painkiller, cough suppressant
• heroin- under investigation
• codeine- painkiller, cough suppressant
• mathadone- treatment of heroin addiction

• Barbiturates- sedative, sleep, anticonvulsant, anesthetic
• Benzodiazepines- antianxiety, sleep, anticonvulsant, sedative
• Alcohol- antiseptic
• Rohypnol- None in U.S. (elsewhere for sedation, anesthesia, and treatment of insomnia)

• Amphetamines- weight control, counteract anesthesia
• Methamphetamine- ADHD, weight control (rarely)
• MDMA (Ecstasy)- None (originally developed as an appetite suppressant)
• Cocaine- local anesthetic
• Nicotine- Gum, patch for cessation of smoking
• Caffeine- Weight control, stimulant in acute respiratory failure, analgesia

• produce changes in consciousness by altering perceptions, creating hallucinations, and blurring the boundary between self and the external world
• Distort the brain's processing of sensory experiences
• users often feel dismebodied or removed from parts of their personality
• Some Native American groups have been known to consume hallucinogens in past history

• Slow down or impair the activity of the CNS. 

• Enhance the activity of the CNS.
• This results in a boost in both mental and physical activity level.

• Caffeine 
• Produces its behavioral effects indirectly. 
• It blocks the action of adenosine. So this is blocking the the release of neurotransmitters. This then allows caffeine to indirectly boost the release of these neurotransmitters
• Nicotine
  • Contains more than 19 known chemicals that can cause cancer.
  • Creates more saliva and phlegm.
• Marijuana
• Smoking pot can increase your heart rate by as much as two times for up to 3 hours. That’s why some people have a heart attack right after they use marijuana.
• It can increase bleeding, lower blood pressure, and affect your blood sugar
• Red eyes and dilated pupils
• Dry mouth
• Heroin
• blood pressure and body temperature drops and the heartbeat can become irregular
• Prescription Drugs
• Cocaine
• In low doses it can increase your alertness and energy that lasts from a few minutes to an hour.
• In high doses it can produce depression and paranoia, as well as life-threatening strokes and seizures.
• Depressants
• They slow

Physical dependence of drugs is an adaptive psychological state that occurs with regular drug use and results in a withdrawal syndrome when the drug use is stopped. Physical dependence occurs because of addiction, but it is not directly associated with addiction itself. Instead, it is normally associated with increased tolerance.

Symptoms of withdrawal from alcohol are: Diarrhea, anxiety, sweating, nausea. 

Symptoms of withdrawal from opiate abuse are: Irritability, fatigue, shaking, sweating, and nausea.

Symptoms of withdrawal from nicotine are: Irritability, fatigue, insomnia, difficulty concentrating, and headaches.

Symptoms of withdrawal of marijuana are: Insomnia, depression, nightmares, vivid dreams.

Symptoms of tolerance to most drugs means that the strongest behavioral effects occur the first few times that the drug is used. So that after a few times of using the drugs they have to do larger doses to produce those same effects from before.

Functional Tolerance: This develops as a result of the changes in the synaptic receptors for that drug. Our neurons adapt to the drug being there so it alters the number of receptors.

Metabolic Tolerance: This occurs because our liver also adapts to the repeated use of certain drugs which causes it to speed up the production of enzymes that can metabolize the drugs. This makes it so the drugs are only activated for a short period of time so they need more and more.