Transcript Document

Drug Types
• Types
– Psychoactive – alters mood or consciousness;
affects neural functioning
– Non-psychoactive – e.g., antibacterial
• Classes of psychoactive drugs
– Sedative-Hypnotics
• E.g. Barbiturates, Anti-anxiety, alcohol
• Reduce anxiety (low), sedation (medium), anesthesia (high)
– Behavioral Stimulants and Consultants
• E.g. Amphetamines, Cocaine, Caffeine, Nicotine
• Increase activity (increase motor activity or counter fatigue)
Drug Types
• Classes of psychoactive drugs
– Narcotic Analgesics
• E.g., Opium, heroine, morphine, codeine
• Relieve Pain
– Antipsychotic Agents
• E.g., Lithium, haloperidol, reserpine
• Used to treat schzophrenia
– Psychedelics and Hallucinogens
• E.g., LSD, Marijuana, MDMA (Ecstasy)
• Alter sensory perception and cognitive processes
Drug Harm
• Nutt et al. (2007) – The Lancet
– Two sets of experts rate drugs on dimensions
of harm
• Physical Harm – acute, chronic, Intravenous
• Dependence – pleasure intensity, psychological
dependence, physical dependence
• Social Harm – Intoxication, other social harm,
health-care costs
Motivation
• Initial (Early) Motivation
• Motivation
– Approach – using to increase positive/mood feelings
– Avoid – using to escape negative mood/feelings
» More likely to become addicted
• Many factors moderate likelihood of initial use
– Self-medication – can be used to alleviate negative state
such as anxiety or depression (e.g., high anxious people
more likely to smoke & use alcohol)
– Temperament – people high in novelty more likely to try
– Social Aspects – peers and/or parents
Motivation
• Continuing Motivation (Craving)
– Physical Dependency
• Body adapts to presence of drugs with physical changes
(e.g., may change number of receptors)
• Drug is required for “normal” operation
• Tolerance
– Greater doses to have same effect
• Withdrawal
– Symptoms associated with cessation
» E.g., headaches, shakes, pain, depression, anxiety, etc.
– Source of motivation – people take drug to prevent negative
symptoms
Motivation
• Continuing Motivation (Craving)
– Psychological Dependency
• Desire for drug in absence of physical need
– Can last months or years
• Can be triggered by cues in environment
– Classical conditioning –pleasure of drug
associated with context, stimulus, or event
– Desire for drug can be evoked by conditioned cue
Tolerance
• Decreased responsiveness to same dose of drug
– More likely with constant drug use
• Types
– Metabolic
• Increasing enzymes to destroy drug
– Cellular
• Cells adjust to be minimize effects
– Learned
• Covering outward signs of intoxication
• Training rats to walk & avoid shock
– Training - Alcohol before training, after training; or no alcohol
– Test – alcohol before – rats who had trained with alcohol did
better than other two conditions
Sensitization
• Increased responsiveness to same dose of
drug
– More likely with occasional drug use
– Context is important
• Sensitization seems to occur when taken in novel
environments
– Very long lasting
• Evidence that sensitization may be due to dendrite
growth
Routes of Drug Administration
• Chemical properties of drugs affect how they
can be administered
– Solubility – fat or water
– Acidity – acid or base
• Modes
– Injection (fastest)
– Absorption
• Lungs
• Mucus membranes (nose)
– Ingestion (slowest)
Your Interests
• Top Individual Drugs
– Heroin (Narcotic)
– Cocaine (Stimulant)
– Marijuana (Psychedelic)
• Top Classes
– Stimulant
– Psychedelic
– Narcotic
Stimulants (Cocaine)
• Psychological Effect
– Euphoria (fairly reliable and intense relative to other
drugs)
– Appetite suppressant
– Increased energy
• Physiological Effect
– Dopamine – blocks re-uptake protein (allows DA to
remain in synapse)
• Chronic use - DA receptor down-regulation
• Depression may result from decreased DA activity after
withdrawal
• Sensitization – brain is more sensitive to things that increase
DA (cocaine)
Stimulants (Cocaine)
• Dopamine
– Central role of DA in addiction
• Electrical stimulation of important DA region of
brain is rewarding
• Most drugs of abuse cause increased DA activity
(increase release or block re-uptake)
– Effects can be direct or indirect (via a different neural
circuit that connects to DA system)
• Drugs that block DA or inhibit DA release are not
abused
Stimulants (Cocaine)
• Physiological Effect
– Norepinephrine
• Blocks re-uptake protein
• NE implicated in attention (stimulants increase NE in helping
with ADD/ADHD)
– Serotonin (5-HT)
• Blocks re-uptake protein
– Sodium Channels
• Blocks sodium channels & interferes with action potentials
• Local anesthetic properties
Stimulants (Cocaine)
• Withdrawal
– Craving – can last months
– Depressed mood – can last months
– Fatigue
– Generalized malaise
– Vivid and unpleasant dreams
– Agitation and restless behavior
– Slowing of activity
– Increased appetite
Psychedelic (Marijuana - THC)
• Psychological Effect
– Vary widely across people & situation
– Mild euphoria (relative to other drugs)
– Relaxation
– Distortions of time and space & sometimes
hallucinations
– Appetite stimulation
– Slight analgesic
Psychedelic (Marijuana - THC)
• Physical Effect
– Agonist for anadamide that binds to CB1 cannabinoid
receptor
• Cannabinoid receptors are very widely distributed in brain
– Anandamide works as second messenger
• Less cAMP – less protein kinaese A
• Affects CA+ & K+ channels – less NTs released (many
different kinds)
– Dopamine influenced indirectly
• DA neurons don’t have CB1 receptors so THC does not
cause less DA release
• GABA neurons normally inhibit DA
– GABA neurons have CB1 receptors and become less active
• More DA because THC inhibits GABA which inhibits DA
Psychedelic (Marijuana - THC)
• Withdrawal
– Insomnia & vivid dreams
– Depression
– Anger
– Headaches
– Night sweats
Narcotic (Heroin & Morphine)
• Heroin vs. Morphine
– Same active chemical
– Heroin is more fat soluble and can enter brain
more easily (converted to Morphine in brain)
• Psychological Effect
– Analgesia (pain relief)
– Euphoria (greater than other opioid drugs)
– Relaxation
Narcotic (Heroin & Morphine)
• Physical Effect
– Agonist for endogenous endorphins (βendorphin, dynorphin, leu-enkephalin, & metenkephalin) that are used to diminish pain
• μ-opioid receptor that is located thought brain,
spinal cord, and gut
• Second messenger system that influences the
likelihood of action potentials (e.g., reducing pain)
– Dopamine influenced indirectly
• μ-opioid receptor decreases GABA
• GABA normally inhibits DA (and many other NTs)
• Increase in DA (inhibit the inhibitor)
Narcotic (Heroin & Morphine)
• Withdrawal
– Sustained use for as little as 3 days can lead to
withdrawal (minor compared to longer use)
– Sweating, anxiety, depression, mailaise, priapism or
genital sensitivity, insomnia, vomiting, diareaha,
cramps, fever
• Many symptoms occur because of hyperactive sympathetic
nervous system
– Very unpleasant but generally not fatal (sedatives
can be fatal)
– Methadone
• Same effects as heroin but is slowly absorbed in stomach
• Relieves withdrawal without the euphoric effect
Drugs & Reward
• Most drugs of abuse seem to activate “reward”
circuit(s) in the brain
– Dopamine is a (the) principle one
– Reward circuit(s) important for normal functioning &
learning
• Food, sex, & other necessary activities that are enjoyable
(interacting with others, mastering a task, etc.)
• All (most) behavior is channeled through these reward
circuit(s) – do not have completely difference systems for
sex, hunger, etc.
• Recent research suggests that it is possible to
separate systems – “liking” vs. “wanting”
– “Liking” - system responsible for pleasure
– “Wanting” – system that drives behavior