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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