[Script Info] Title: [Events] Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text Dialogue: 0,0:00:06.22,0:00:07.72,Default,,0000,0000,0000,,In 1970, Dialogue: 0,0:00:07.72,0:00:13.14,Default,,0000,0000,0000,,marijuana was classified \Nas a schedule 1 drug in the United States: Dialogue: 0,0:00:13.14,0:00:15.74,Default,,0000,0000,0000,,the strictest designation possible, Dialogue: 0,0:00:15.74,0:00:20.78,Default,,0000,0000,0000,,meaning it was completely illegal \Nand had no recognized medical uses. Dialogue: 0,0:00:20.78,0:00:23.53,Default,,0000,0000,0000,,For decades, this view persisted Dialogue: 0,0:00:23.53,0:00:28.54,Default,,0000,0000,0000,,and set back research \Non the drug's mechanisms and effects. Dialogue: 0,0:00:28.54,0:00:33.03,Default,,0000,0000,0000,,Today, marijuana’s therapeutic benefits \Nare widely acknowledged, Dialogue: 0,0:00:33.03,0:00:36.09,Default,,0000,0000,0000,,and some nations \Nhave legalized medical use Dialogue: 0,0:00:36.09,0:00:38.48,Default,,0000,0000,0000,,or are moving in that direction. Dialogue: 0,0:00:38.48,0:00:42.38,Default,,0000,0000,0000,,But a growing recognition \Nfor marijuana’s medical value Dialogue: 0,0:00:42.38,0:00:44.08,Default,,0000,0000,0000,,doesn’t answer the question: Dialogue: 0,0:00:44.08,0:00:49.10,Default,,0000,0000,0000,,is recreational marijuana use \Nbad for your brain? Dialogue: 0,0:00:49.10,0:00:52.80,Default,,0000,0000,0000,,Marijuana acts \Non the body’s cannabinoid system, Dialogue: 0,0:00:52.80,0:00:56.44,Default,,0000,0000,0000,,which has receptors \Nall over the brain and body. Dialogue: 0,0:00:56.44,0:01:01.04,Default,,0000,0000,0000,,Molecules native to the body, \Ncalled endocannabinoids, Dialogue: 0,0:01:01.04,0:01:03.70,Default,,0000,0000,0000,,also act on these receptors. Dialogue: 0,0:01:03.70,0:01:07.47,Default,,0000,0000,0000,,We don’t totally understand \Nthe cannabinoid system, Dialogue: 0,0:01:07.47,0:01:12.14,Default,,0000,0000,0000,,but it has one feature \Nthat provides a big clue to its function. Dialogue: 0,0:01:12.14,0:01:15.89,Default,,0000,0000,0000,,Most neurotransmitters \Ntravel from one neuron to the next Dialogue: 0,0:01:15.89,0:01:19.46,Default,,0000,0000,0000,,through a synapse to propagate a message. Dialogue: 0,0:01:19.46,0:01:23.22,Default,,0000,0000,0000,,But endocannabinoids \Ntravel in the opposite direction. Dialogue: 0,0:01:23.22,0:01:26.72,Default,,0000,0000,0000,,When a message passes \Nfrom the one neuron to the next, Dialogue: 0,0:01:26.72,0:01:30.63,Default,,0000,0000,0000,,the receiving neuron \Nreleases endocannabinoids. Dialogue: 0,0:01:30.63,0:01:33.61,Default,,0000,0000,0000,,Those endocannabinoids \Ntravel backward Dialogue: 0,0:01:33.61,0:01:35.75,Default,,0000,0000,0000,,to influence the sending neuron— Dialogue: 0,0:01:35.75,0:01:40.42,Default,,0000,0000,0000,,essentially giving it feedback \Nfrom the receiving neuron. Dialogue: 0,0:01:40.42,0:01:44.50,Default,,0000,0000,0000,,This leads scientists \Nto believe that the endocannabinoid system Dialogue: 0,0:01:44.50,0:01:48.29,Default,,0000,0000,0000,,serves primarily \Nto modulate other kinds of signals— Dialogue: 0,0:01:48.29,0:01:51.83,Default,,0000,0000,0000,,amplifying some and diminishing others. Dialogue: 0,0:01:51.83,0:01:57.16,Default,,0000,0000,0000,,Feedback from endocannabinoids \Nslows down rates of neural signaling. Dialogue: 0,0:01:57.16,0:01:59.09,Default,,0000,0000,0000,,That doesn’t necessarily mean Dialogue: 0,0:01:59.09,0:02:01.92,Default,,0000,0000,0000,,it slows down behavior \Nor perception, though. Dialogue: 0,0:02:01.92,0:02:05.98,Default,,0000,0000,0000,,For example, \Nslowing down a signal that inhibits smell Dialogue: 0,0:02:05.98,0:02:09.65,Default,,0000,0000,0000,,could actually make smells more intense. Dialogue: 0,0:02:09.65,0:02:13.50,Default,,0000,0000,0000,,Marijuana contains \Ntwo main active compounds, Dialogue: 0,0:02:13.50,0:02:21.90,Default,,0000,0000,0000,,tetrahydrocannabinol or THC, \Nand cannabidiol, or CBD. Dialogue: 0,0:02:21.90,0:02:27.60,Default,,0000,0000,0000,,THC is thought to be primarily responsible\Nfor marijuana’s psychoactive effects Dialogue: 0,0:02:27.60,0:02:30.47,Default,,0000,0000,0000,,on behavior, cognition, and perception, Dialogue: 0,0:02:30.47,0:02:35.41,Default,,0000,0000,0000,,while CBD is responsible \Nfor the non-psychoactive effects. Dialogue: 0,0:02:35.41,0:02:37.77,Default,,0000,0000,0000,,Like endocannabinoids, Dialogue: 0,0:02:37.77,0:02:43.36,Default,,0000,0000,0000,,THC slows down signaling \Nby binding to cannabinoid receptors. Dialogue: 0,0:02:43.36,0:02:47.47,Default,,0000,0000,0000,,But it binds to receptors \Nall over this sprawling, diffuse system Dialogue: 0,0:02:47.47,0:02:48.32,Default,,0000,0000,0000,,at once, Dialogue: 0,0:02:48.32,0:02:52.29,Default,,0000,0000,0000,,whereas endocannabinoids \Nare released in a specific place Dialogue: 0,0:02:52.29,0:02:55.22,Default,,0000,0000,0000,,in response to a specific stimulus. Dialogue: 0,0:02:55.22,0:02:58.02,Default,,0000,0000,0000,,This widespread activity \Ncoupled with the fact Dialogue: 0,0:02:58.02,0:03:02.42,Default,,0000,0000,0000,,that the cannabinoid system\Nindirectly affects many other systems, Dialogue: 0,0:03:02.42,0:03:06.56,Default,,0000,0000,0000,,means that each person’s \Nparticular brain chemistry, genetics, Dialogue: 0,0:03:06.56,0:03:08.94,Default,,0000,0000,0000,,and previous life experience Dialogue: 0,0:03:08.94,0:03:11.99,Default,,0000,0000,0000,,largely determine \Nhow they experience the drug. Dialogue: 0,0:03:11.99,0:03:16.10,Default,,0000,0000,0000,,That’s true much more so with marijuana \Nthan with other drugs Dialogue: 0,0:03:16.10,0:03:20.73,Default,,0000,0000,0000,,that produce their effects \Nthrough one or a few specific pathways. Dialogue: 0,0:03:20.73,0:03:26.17,Default,,0000,0000,0000,,So the harmful effects, if any, \Nvary considerably from person to person. Dialogue: 0,0:03:26.17,0:03:28.73,Default,,0000,0000,0000,,And while we don’t know \Nhow exactly how marijuana Dialogue: 0,0:03:28.73,0:03:31.21,Default,,0000,0000,0000,,produces specific harmful effects, Dialogue: 0,0:03:31.21,0:03:34.86,Default,,0000,0000,0000,,there are clear risk factors \Nthat can increase peoples’ likelihood Dialogue: 0,0:03:34.86,0:03:37.04,Default,,0000,0000,0000,,of experiencing them. Dialogue: 0,0:03:37.04,0:03:40.00,Default,,0000,0000,0000,,The clearest risk factor is age. Dialogue: 0,0:03:40.00,0:03:42.13,Default,,0000,0000,0000,,In people younger than 25, Dialogue: 0,0:03:42.13,0:03:46.11,Default,,0000,0000,0000,,cannabinoid receptors \Nare more concentrated in the white matter Dialogue: 0,0:03:46.11,0:03:48.53,Default,,0000,0000,0000,,than in people over 25. Dialogue: 0,0:03:48.53,0:03:51.62,Default,,0000,0000,0000,,The white matter \Nis involved in communication, Dialogue: 0,0:03:51.62,0:03:54.87,Default,,0000,0000,0000,,learning, memory, and emotions. Dialogue: 0,0:03:54.87,0:03:56.28,Default,,0000,0000,0000,,Frequent marijuana use Dialogue: 0,0:03:56.28,0:03:59.25,Default,,0000,0000,0000,,can disrupt the development \Nof white matter tracts, Dialogue: 0,0:03:59.25,0:04:03.44,Default,,0000,0000,0000,,and also affect the brain’s ability \Nto grow new connections. Dialogue: 0,0:04:03.44,0:04:08.09,Default,,0000,0000,0000,,This may damage long-term learning ability\Nand problem solving. Dialogue: 0,0:04:08.09,0:04:11.48,Default,,0000,0000,0000,,For now, it’s unclear \Nhow severe this damage can be Dialogue: 0,0:04:11.48,0:04:13.08,Default,,0000,0000,0000,,or whether it’s reversible. Dialogue: 0,0:04:13.08,0:04:14.85,Default,,0000,0000,0000,,And even among young people, Dialogue: 0,0:04:14.85,0:04:17.89,Default,,0000,0000,0000,,the risk is higher the younger someone is— Dialogue: 0,0:04:17.89,0:04:22.52,Default,,0000,0000,0000,,much higher for a 15 year old \Nthan a 22 year old, for instance. Dialogue: 0,0:04:22.52,0:04:27.11,Default,,0000,0000,0000,,Marijuana can also cause hallucinations \Nor paranoid delusions. Dialogue: 0,0:04:27.11,0:04:29.84,Default,,0000,0000,0000,,Known as marijuana-induced psychosis, Dialogue: 0,0:04:29.84,0:04:33.84,Default,,0000,0000,0000,,these symptoms usually subside \Nwhen a person stops using marijuana. Dialogue: 0,0:04:33.84,0:04:37.28,Default,,0000,0000,0000,,But in rare cases, \Npsychosis doesn’t subside, Dialogue: 0,0:04:37.28,0:04:41.71,Default,,0000,0000,0000,,instead unmasking \Na persistent psychotic disorder. Dialogue: 0,0:04:41.71,0:04:46.25,Default,,0000,0000,0000,,A family history of psychotic disorders, \Nlike schizophrenia, Dialogue: 0,0:04:46.25,0:04:49.43,Default,,0000,0000,0000,,is the clearest, though not the only, \Nrisk factor for this effect. Dialogue: 0,0:04:49.43,0:04:53.96,Default,,0000,0000,0000,,Marijuana-induced psychosis \Nis also more common among young adults, Dialogue: 0,0:04:53.96,0:04:56.47,Default,,0000,0000,0000,,though it’s worth noting \Nthat psychotic disorders Dialogue: 0,0:04:56.47,0:04:59.20,Default,,0000,0000,0000,,usually surface in this age range anyway. Dialogue: 0,0:04:59.20,0:05:03.09,Default,,0000,0000,0000,,What’s unclear in these cases \Nis whether the psychotic disorder Dialogue: 0,0:05:03.09,0:05:05.40,Default,,0000,0000,0000,,would have appeared \Nwithout marijuana use— Dialogue: 0,0:05:05.40,0:05:07.99,Default,,0000,0000,0000,,whether marijuana use triggers it early, Dialogue: 0,0:05:07.99,0:05:12.24,Default,,0000,0000,0000,,is a catalyst for a tipping point \Nthat wouldn’t have been crossed otherwise, Dialogue: 0,0:05:12.24,0:05:15.96,Default,,0000,0000,0000,,or whether the reaction \Nto marijuana is merely an indication Dialogue: 0,0:05:15.96,0:05:18.17,Default,,0000,0000,0000,,of an underlying disorder. Dialogue: 0,0:05:18.17,0:05:23.39,Default,,0000,0000,0000,,In all likelihood, marijuana’s role \Nvaries from person to person. Dialogue: 0,0:05:23.39,0:05:25.94,Default,,0000,0000,0000,,At any age, as with many other drugs, Dialogue: 0,0:05:25.94,0:05:27.24,Default,,0000,0000,0000,,the brain and body Dialogue: 0,0:05:27.24,0:05:31.21,Default,,0000,0000,0000,,become less sensitive \Nto marijuana after repeated uses, Dialogue: 0,0:05:31.21,0:05:35.11,Default,,0000,0000,0000,,meaning it takes more \Nto achieve the same effects. Dialogue: 0,0:05:35.11,0:05:37.94,Default,,0000,0000,0000,,Fortunately, unlike many other drugs, Dialogue: 0,0:05:37.94,0:05:41.23,Default,,0000,0000,0000,,there’s no risk of fatal overdose \Nfrom marijuana, Dialogue: 0,0:05:41.23,0:05:44.20,Default,,0000,0000,0000,,and even heavy use \Ndoesn’t lead to debilitating Dialogue: 0,0:05:44.20,0:05:48.27,Default,,0000,0000,0000,,or life-threatening \Nwithdrawal symptoms if use stops. Dialogue: 0,0:05:48.27,0:05:52.18,Default,,0000,0000,0000,,There are more subtle forms \Nof marijuana withdrawal, though, Dialogue: 0,0:05:52.18,0:05:56.85,Default,,0000,0000,0000,,including sleep disturbances, \Nirritability, and depressed mood, Dialogue: 0,0:05:56.85,0:06:00.66,Default,,0000,0000,0000,,which pass \Nwithin a few weeks of stopping use. Dialogue: 0,0:06:00.66,0:06:03.22,Default,,0000,0000,0000,,So is marijuana bad for your brain? Dialogue: 0,0:06:03.22,0:06:05.34,Default,,0000,0000,0000,,It depends who you are. Dialogue: 0,0:06:05.34,0:06:08.86,Default,,0000,0000,0000,,But while some risk factors \Nare easy to identify, Dialogue: 0,0:06:08.86,0:06:11.13,Default,,0000,0000,0000,,others aren’t well understood— Dialogue: 0,0:06:11.13,0:06:16.08,Default,,0000,0000,0000,,which means there’s still some possibility\Nof experiencing negative effects, Dialogue: 0,0:06:16.08,0:06:19.78,Default,,0000,0000,0000,,even if you don’t have \Nany of the known risk factors.