Drug Addiction and the Brain

00:09:20
https://www.youtube.com/watch?v=62FYNwd-8Jo

概要

TLDRDrugs, which are substances that have a physiological effect when ingested, can range from common ones like caffeine to illicit ones. They affect the body in various ways depending on how they're introduced—ingestion, injection, inhalation, or absorption. Some drugs penetrate the blood-brain barrier, becoming psychoactive and influencing brain activity by binding to receptors or affecting neurotransmitters. Tolerance to drugs can develop, leading to higher doses being required for the same effect, and withdrawal symptoms upon sudden cessation indicate physical dependence. Addiction involves habitual drug use regardless of negative effects, and can be physical or psychological. Common addictive substances include nicotine, which stimulates dopamine release, and alcohol, which impacts various brain functions and may have a genetic predisposition. Cocaine increases neural activity by inhibiting dopamine reuptake. Overall, understanding addiction involves both physical dependence and the psychological craving for drug-induced pleasure, with dopamine playing a critical role. Future discussions will delve deeper into specific drugs and their effects.

収穫

  • 💊 Drugs can range from harmless to illicit substances, affecting the body physiologically.
  • 🚪 Drugs enter the body via ingestion, injection, inhalation, or absorption into mucous membranes.
  • 🧠 Psychoactive drugs affect the brain by crossing the blood-brain barrier and influencing neurotransmitters.
  • 🔄 Repeated drug use leads to tolerance, requiring more to achieve the same effect.
  • ⚠️ Sudden drug elimination can cause withdrawal symptoms, indicating physical dependence.
  • 🔗 Addiction involves both physical dependence and psychological craving, impacting health and social life.
  • 🚬 Nicotine in tobacco is addictive, affecting acetylcholine receptors and stimulating dopamine release.
  • 🍸 Alcohol affects various brain regions, leading to changes in inhibition, movement, and consciousness.
  • ⚡ Cocaine keeps dopamine levels high by blocking reuptake, stimulating neural activity.
  • 💉 Opiates mimic natural pain reduction mechanisms, causing euphoria and high addiction potential.
  • 🔬 Dopamine is crucial in addiction, influencing pleasure and reinforcement in the brain.
  • 🎓 The upcoming pharmacology series will explore specific drugs and their mechanisms in detail.

タイムライン

  • 00:00:00 - 00:09:20

    Professor Dave introduces the topic of drug addiction, discussing how drugs can range from common substances like caffeine to illicit drugs and how they affect the body. He notes that drug addiction will be looked at through the lens of biopsychology, focusing on how addiction occurs and what it looks like in the brain.

マインドマップ

ビデオQ&A

  • What is defined as a drug?

    A drug is any substance that has a physiological effect when ingested.

  • How can drugs enter the body?

    Drugs can be ingested orally, injected, inhaled, or absorbed through mucous membranes.

  • What are psychoactive drugs?

    Psychoactive drugs are those that affect the mind, often penetrating the blood-brain barrier.

  • What is drug tolerance?

    Drug tolerance is a decreased sensitivity to a drug with regular exposure, requiring higher doses for the same effect.

  • What causes withdrawal symptoms?

    Withdrawal symptoms occur when the body is suddenly deprived of a drug it has grown accustomed to.

  • What are some examples of addictive substances?

    Examples of addictive substances include tobacco, alcohol, cocaine, and opiates.

  • What is the role of dopamine in addiction?

    Dopamine is a crucial component in addiction, involved in the pleasure and reinforcement aspects.

  • How does nicotine affect the brain?

    Nicotine acts on nicotinic cholinergic receptors, resulting in dopamine release and pleasure sensations.

  • What genetic factors influence alcohol addiction?

    There is a genetic predisposition to alcohol addiction, with about a 50% probability of being inherited.

  • How does cocaine affect neural activity?

    Cocaine inhibits the reuptake of dopamine, increasing neural activity by keeping dopamine levels high.

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  • 00:00:00
    It’s Professor Dave, let’s check out your brain on drugs.
  • 00:00:10
    A drug is defined as any substance that has a physiological effect when ingested.
  • 00:00:17
    Drugs can therefore range from something as common as aspirin or caffeine to all the illicit
  • 00:00:22
    or hallucinogenic substances that typically come to mind during any discussion of drugs.
  • 00:00:28
    A thorough analysis of specific drugs and how they interact with the body to produce
  • 00:00:34
    a particular physiological effect will have to wait for the upcoming pharmacology series.
  • 00:00:41
    But in the context of biopsychology, the phenomenon of drug addiction will be of significant interest to us.
  • 00:00:50
    What does it mean to get addicted to a drug?
  • 00:00:53
    How does this happen, and what does the corresponding brain activity look like?
  • 00:00:58
    Let’s take a closer look at the drug-addicted brain now.
  • 00:01:04
    Drugs enter the body in a few different ways.
  • 00:01:06
    They can be ingested orally, like a pill, injected into the bloodstream, inhaled into
  • 00:01:13
    the lungs, or absorbed through any of the external mucous membranes of the body.
  • 00:01:20
    The path taken will impact the severity of the effect, as well as the rate of its onset.
  • 00:01:26
    The bloodstream is the most direct, and thus the fastest and most predictable, while the
  • 00:01:32
    other methods eventually make it to the bloodstream after being absorbed into blood vessels from
  • 00:01:38
    wherever they were administered.
  • 00:01:42
    Some drugs are able to penetrate the blood-brain barrier that we discussed earlier, thus making
  • 00:01:47
    their way into the brain, while others are not.
  • 00:01:51
    Of the ones that do, most can be referred to as psychoactive drugs, which generally
  • 00:01:56
    means any drug that affects the mind.
  • 00:02:00
    This is typically achieved in one of several ways.
  • 00:02:03
    Some drugs bind to certain synaptic receptors, acting as inhibitors, also called antagonists,
  • 00:02:11
    while others bind and behave as agonists, meaning that they mimic the role of the native ligand.
  • 00:02:19
    Some drugs influence the synthesis, transport, release, or deactivation of specific neurotransmitters.
  • 00:02:29
    Whatever the case may be, the drug will continue to have its particular effect until it is
  • 00:02:34
    metabolized by enzymes, which essentially chop them up until they can no longer perform
  • 00:02:40
    any function.
  • 00:02:41
    The body will respond to the presence or absence of a drug differently over time.
  • 00:02:47
    If exposed to a particular drug regularly, a tolerance can be developed.
  • 00:02:53
    This is a decreased sensitivity to the drug, either in the way of metabolic tolerance,
  • 00:02:59
    where less and less of the drug makes it to its destination, or functional tolerance,
  • 00:03:05
    where the drug makes it to where its going, but its efficacy diminishes, often because
  • 00:03:10
    receptors undergo endocytosis.
  • 00:03:14
    If the body grows accustomed to a drug, its sudden elimination can trigger symptoms of
  • 00:03:20
    withdrawal.
  • 00:03:22
    These tend to be the opposite of the effects of the drug, and if withdrawal is experienced,
  • 00:03:28
    it means a physical dependency has developed.
  • 00:03:32
    This is a big part of what we refer to as drug addiction.
  • 00:03:36
    A drug addict will use a particular drug habitually, despite the adverse effects on the health
  • 00:03:43
    or social life of the individual.
  • 00:03:46
    This goes beyond a mere physical dependence that can develop with certain substances,
  • 00:03:51
    as addiction can also be a psychological condition, as is evidenced by addictions to activities
  • 00:03:58
    like gambling, which has nothing to do with any substance, but works quite similarly from
  • 00:04:04
    a neural standpoint.
  • 00:04:07
    While physical addiction can arise with a wide variety of substances, a few common ones
  • 00:04:13
    are tobacco, alcohol, cocaine, and opiates.
  • 00:04:18
    We can examine these to introduce a few concepts.
  • 00:04:22
    With tobacco, there are many compounds that are ingested, and many of these are harmful
  • 00:04:27
    to one’s health, but the one that causes addiction is nicotine.
  • 00:04:33
    This acts on nicotinic cholinergic receptors in the brain.
  • 00:04:37
    These normally respond to acetylcholine, but nicotine is an agonist for these receptors
  • 00:04:43
    as well.
  • 00:04:44
    This causes the receptors to open, allowing ions to enter, which eventually results in
  • 00:04:50
    the release of neurotransmitters like dopamine, which generates a pleasurable sensation.
  • 00:04:58
    The brain responds through neuroadaptation, affecting the binding sites for nicotine,
  • 00:05:04
    which produces withdrawal symptoms, thus establishing tolerance and dependence.
  • 00:05:12
    Nicotine addiction can arise very quickly, even after just a few weeks of regular use.
  • 00:05:20
    In alcoholic beverages, the active agent is ethanol.
  • 00:05:24
    This interacts with the brain in a variety of ways.
  • 00:05:27
    In the cerebral cortex, behavioral inhibitory centers are depressed, which lowers behavioral
  • 00:05:33
    inhibition, and processing of information slows down.
  • 00:05:38
    It affects the center of movement and balance in the cerebellum, as well as the medulla,
  • 00:05:44
    which impacts breathing and consciousness.
  • 00:05:49
    Long-term alcohol exposure causes neurological changes resulting in tolerance, which then
  • 00:05:55
    causes excitation of certain neurotransmitter systems as well as withdrawal symptoms in
  • 00:06:01
    absence of the drug.
  • 00:06:04
    This is alcohol addiction.
  • 00:06:07
    There is also a major genetic component to alcohol addiction, or a predisposition that
  • 00:06:13
    has about a fifty percent probability of being passed on to offspring.
  • 00:06:18
    Cocaine, on the other hand, is a stimulant, meaning it increases neural activity.
  • 00:06:25
    It acts by inhibiting the reuptake of dopamine from the synaptic space, thus keeping their
  • 00:06:31
    levels quite high.
  • 00:06:34
    And finally, opiates like heroin and morphine bind to opioid receptors that normally bind
  • 00:06:42
    to endogenous neurotransmitters like endorphins, so they mimic innate mechanisms of pain reduction,
  • 00:06:48
    causing euphoria.
  • 00:06:51
    Heroin is widely regarded as the most addictive substance we are aware of.
  • 00:06:57
    As we mentioned, we will get a much closer look at specific drugs and their mechanisms
  • 00:07:02
    of action during the upcoming pharmacology series.
  • 00:07:07
    For now, let’s mention just a few more things about the brain and addiction in a general sense.
  • 00:07:14
    As we have begun to discuss, an understanding of addiction must combine the notion of physical
  • 00:07:21
    dependence with positive incentive.
  • 00:07:24
    Sometimes drug use involves a direct effort to alleviate withdrawal symptoms.
  • 00:07:29
    However, a very high percentage of drug users that go through rehabilitation and completely
  • 00:07:36
    rid themselves of physical dependence will nevertheless return to the drug, illustrating
  • 00:07:43
    that the craving for the pleasurable properties of the drug is a huge factor with addiction.
  • 00:07:51
    Countless experiments done with rats in isolation show that they will self-administer electrical
  • 00:07:57
    stimulation to pleasure-producing areas of the brain, foregoing essentially all other
  • 00:08:03
    activity in favor of maintaining this stimulation.
  • 00:08:09
    Dopaminergic neurons project from the midbrain into a number of regions of the telencephalon,
  • 00:08:15
    including the prefrontal cortex, limbic cortex, amygdala, and more, and these structures are
  • 00:08:23
    heavily involved with this self-stimulating behavior.
  • 00:08:28
    We can therefore identify dopamine as a crucial component of drug addiction, or addiction
  • 00:08:35
    in general.
  • 00:08:38
    There is much more to discuss regarding drugs, in both a recreational and medicinal context,
  • 00:08:44
    but right now let’s move on to some other topics in biopsychology.
タグ
  • drugs
  • addiction
  • brain
  • neurotransmitters
  • withdrawal
  • tolerance
  • psychoactive
  • tobacco
  • alcohol
  • cocaine
  • opiates
  • dopamine