WEBVTT 00:02.566 --> 00:05.300 align:left position:0%,start line:73.33% size:100% JUDY WOODRUFF: All this week, we're looking at the impact of the wave of marijuana legalization. 00:07.266 --> 00:10.566 align:left position:0%,start line:80% size:100% One of the key questions is whether marijuana is generally more potent now and whether that 00:11.966 --> 00:13.966 align:left position:0%,start line:86.67% size:100% poses an increased health risk for some people. 00:13.966 --> 00:18.966 align:left position:0%,start line:80% size:100% It's also coming amid debates surrounding the larger benefits and risks of marijuana. 00:20.933 --> 00:24.466 align:left position:0%,start line:80% size:100% For our Leading Edge segment, Miles O'Brien sifts through the science around what's known 00:25.566 --> 00:27.066 align:left position:12.5%,start line:86.67% size:87.5% and not known about these claims. 00:27.066 --> 00:30.733 align:left position:0%,start line:86.67% size:100% It's part of a close look at The Green Rush around the country. 00:30.733 --> 00:35.733 align:left position:0%,start line:80% size:100% MILES O'BRIEN: For connoisseurs of cannabis, these are heady times indeed. 00:37.200 --> 00:40.400 align:left position:0%,start line:86.67% size:100% MAN: It's pretty much like Toys 'R' Us for adults now. 00:40.400 --> 00:45.366 align:left position:0%,start line:80% size:100% MILES O'BRIEN: We caught up with Levon at a jammed dispensary in Leicester, Massachusetts. 00:46.800 --> 00:50.400 align:left position:0%,start line:86.67% size:100% He had just bought some cannabis oil and a pre-rolled joint. 00:50.400 --> 00:53.033 align:left position:12.5%,start line:86.67% size:87.5% MAN: No one really gets in trouble with this. 00:53.033 --> 00:56.766 align:left position:0%,start line:80% size:100% So, it's nice not being hassled and things like that just for smoking weed. 00:56.766 --> 01:01.733 align:left position:0%,start line:73.33% size:100% MILES O'BRIEN: The state is among 11 and the District of Columbia that have legalized recreational 01:02.933 --> 01:05.866 align:left position:12.5%,start line:86.67% size:87.5% use of marijuana for those 21 and older. 01:05.866 --> 01:08.166 align:left position:12.5%,start line:86.67% size:87.5% MAN: Can't complain there one bit. 01:08.166 --> 01:10.366 align:left position:0%,start line:86.67% size:100% Looking forward to enjoying this when I get home. 01:10.366 --> 01:15.366 align:left position:0%,start line:80% size:100% MILES O'BRIEN: Massachusetts is among 47 states that have sanctioned cannabis for medical 01:16.100 --> 01:18.166 align:left position:12.5%,start line:93.33% size:87.5% purposes as well. 01:18.166 --> 01:23.166 align:left position:0%,start line:80% size:100% It's a stark contrast from the days of reefer madness, the war on drugs and the vilification 01:25.200 --> 01:28.700 align:left position:0%,start line:80% size:100% of a plant that humans have used for more than 2500 years, precious little of it informed 01:31.866 --> 01:33.933 align:left position:25%,start line:93.33% size:75% by research. 01:33.933 --> 01:36.000 align:left position:0%,start line:80% size:100% RONALD REAGAN, President of the United States: What an insult it will be to what we are and 01:36.000 --> 01:40.833 align:left position:0%,start line:80% size:100% whence we came if we do not rise up together in defiance against this cancer of drugs. 01:41.566 --> 01:44.133 align:left position:37.5%,start line:93.33% size:62.5% DR. 01:44.133 --> 01:46.533 align:left position:0%,start line:73.33% size:100% STACI GRUBER, Harvard Medical School: It was much more motivated by sociopolitical pressures, 01:46.533 --> 01:49.233 align:left position:12.5%,start line:86.67% size:87.5% if you will, not a ton of real scientific data. 01:49.233 --> 01:51.300 align:left position:0%,start line:93.33% size:100% A lot of assumptions were made. 01:51.300 --> 01:55.833 align:left position:0%,start line:80% size:100% MILES O'BRIEN: Neuroscientist Staci Gruber is an associate professor of psychiatry at 01:55.833 --> 02:00.833 align:left position:12.5%,start line:73.33% size:87.5% Harvard Medical School and director of the Marijuana Investigations for Neuroscientific 02:02.000 --> 02:05.266 align:left position:12.5%,start line:86.67% size:87.5% Discovery Program at McLean Hospital. 02:05.266 --> 02:09.900 align:left position:0%,start line:80% size:100% She has been studying how cannabis affects the human brain for more than two decades. 02:09.900 --> 02:12.400 align:left position:37.5%,start line:93.33% size:62.5% DR. 02:12.400 --> 02:14.366 align:left position:0%,start line:73.33% size:100% STACI GRUBER: We're still playing catchup in terms of trying to understand what we really 02:14.366 --> 02:16.866 align:left position:0%,start line:80% size:100% need to understand about cannabis and cannabinoids and how they work. 02:16.866 --> 02:21.766 align:left position:0%,start line:73.33% size:100% MILES O'BRIEN: She's doing her best to fill the gaps of understanding by imaging the brains 02:21.766 --> 02:26.766 align:left position:0%,start line:73.33% size:100% of teens and emerging adults, some heavy cannabis users who started very young, and others who 02:28.633 --> 02:30.600 align:left position:25%,start line:93.33% size:75% are weed-free. 02:30.600 --> 02:34.866 align:left position:0%,start line:80% size:100% When they conduct cognitive tests, their brains look very different. 02:34.866 --> 02:37.900 align:left position:0%,start line:86.67% size:100% They use different regions to get the job done. 02:37.900 --> 02:39.966 align:left position:37.5%,start line:93.33% size:62.5% DR. 02:39.966 --> 02:41.333 align:left position:0%,start line:80% size:100% STACI GRUBER: These patterns of activations suggest there is really something different 02:41.333 --> 02:43.366 align:left position:0%,start line:86.67% size:100% in the way they're processing the information. 02:43.366 --> 02:47.433 align:left position:0%,start line:80% size:100% MILES O'BRIEN: The data suggests that heavy recreational use of cannabis during adolescence 02:49.933 --> 02:52.666 align:left position:0%,start line:73.33% size:100% and emerging adulthood inhibits the development of the prefrontal cortex, the decision-making 02:54.066 --> 02:56.366 align:left position:12.5%,start line:93.33% size:87.5% center of the brain. 02:56.366 --> 03:01.166 align:left position:0%,start line:80% size:100% And Gruber also reports evidence of changes in the white matter, which connects various 03:01.166 --> 03:03.100 align:left position:12.5%,start line:93.33% size:87.5% regions of the brain. 03:03.100 --> 03:07.833 align:left position:0%,start line:86.67% size:100% The white matter in pot users is less organized and coherent. 03:07.833 --> 03:11.533 align:left position:12.5%,start line:80% size:87.5% These individuals also self-report more impulsive behavior. 03:11.533 --> 03:12.800 align:left position:37.5%,start line:93.33% size:62.5% DR. 03:12.800 --> 03:14.833 align:left position:12.5%,start line:86.67% size:87.5% STACI GRUBER: We know some things, for sure. 03:14.833 --> 03:19.133 align:left position:0%,start line:80% size:100% We know that there are likely negative effects if cannabis becomes a regular part of one's 03:20.366 --> 03:22.400 align:left position:0%,start line:86.67% size:100% routine when we're neurodevelopmentally vulnerable. 03:22.400 --> 03:27.100 align:left position:12.5%,start line:73.33% size:87.5% That is, we're just still growing up, we're under construction, or half-baked, better 03:27.700 --> 03:29.800 align:left position:25%,start line:93.33% size:75% way to put it. 03:29.800 --> 03:33.133 align:left position:12.5%,start line:73.33% size:87.5% MILES O'BRIEN: And the pot is much stronger than it was a generation ago, when it contained, 03:35.100 --> 03:38.300 align:left position:0%,start line:80% size:100% on average, about 5 percent THC, the psychoactive main ingredient in marijuana. 03:40.266 --> 03:44.733 align:left position:0%,start line:80% size:100% Today, the plants themselves have been bred to be much more potent, 12 percent THC on 03:46.133 --> 03:47.366 align:left position:37.5%,start line:93.33% size:62.5% average. 03:47.366 --> 03:50.600 align:left position:12.5%,start line:86.67% size:87.5% Strains over 20 percent are widely available. 03:50.600 --> 03:55.100 align:left position:0%,start line:86.67% size:100% But that is still not enough for Dario and his friends. 03:55.100 --> 04:00.133 align:left position:0%,start line:73.33% size:100% They frequently use highly concentrated cannabis products known as shatter, oil and wax with 04:02.166 --> 04:06.733 align:left position:0%,start line:80% size:100% average THC levels of more than 50 percent, up to 80 percent and even higher. 04:08.700 --> 04:13.400 align:left position:0%,start line:80% size:100% They prefer the concentrates in part because they get more buzz for their buck. 04:14.933 --> 04:18.933 align:left position:0%,start line:86.67% size:100% MAN: The high is a little different, I would say. 04:18.933 --> 04:23.933 align:left position:0%,start line:80% size:100% And you definitely get, like, higher off of the oil, which is enjoyable, for sure. 04:25.533 --> 04:28.966 align:left position:12.5%,start line:80% size:87.5% MILES O'BRIEN: But what are the consequences of this high-test high? 04:29.700 --> 04:30.233 align:left position:12.5%,start line:93.33% size:87.5% The data is scant. 04:30.233 --> 04:32.200 align:left position:37.5%,start line:93.33% size:62.5% DR. 04:32.200 --> 04:34.666 align:left position:0%,start line:80% size:100% STACI GRUBER: Do they simply use less of a more potent product to get the same effect? 04:34.666 --> 04:38.100 align:left position:0%,start line:80% size:100% And some studies have actually reported that, and some others have reported not so much. 04:38.100 --> 04:41.833 align:left position:0%,start line:80% size:100% So, I think that's a type of investigation I would very much like to see done. 04:41.833 --> 04:45.433 align:left position:0%,start line:86.67% size:100% MILES O'BRIEN: Important, but right now impossible. 04:45.433 --> 04:50.433 align:left position:12.5%,start line:73.33% size:87.5% Despite the trend toward legalization by the states, marijuana is still classified by the 04:52.933 --> 04:55.633 align:left position:0%,start line:73.33% size:100% federal government as a Schedule 1 drug, meaning it supposedly has no currently accepted medical 04:56.833 --> 05:01.200 align:left position:12.5%,start line:86.67% size:87.5% use and a high potential for abuse. 05:01.200 --> 05:05.966 align:left position:0%,start line:80% size:100% This makes it very difficult for researchers to do their work legally. 05:05.966 --> 05:10.666 align:left position:0%,start line:80% size:100% Cannabis used in scientific studies must be acquired from a government-sanctioned grow 05:10.666 --> 05:13.833 align:left position:12.5%,start line:86.67% size:87.5% site at the University of Mississippi. 05:13.833 --> 05:18.766 align:left position:0%,start line:86.67% size:100% And it only produces flower, not the high-concentrate products. 05:18.766 --> 05:23.600 align:left position:12.5%,start line:86.67% size:87.5% There is an urgent need to do this science. 05:23.600 --> 05:28.133 align:left position:0%,start line:80% size:100% Dost Ongur is chief of the Psychotic Disorders Division at McLean Hospital. 05:28.133 --> 05:30.500 align:left position:37.5%,start line:93.33% size:62.5% DR. 05:30.500 --> 05:33.033 align:left position:0%,start line:73.33% size:100% DOST ONGUR, McLean Hospital: Research is showing that if you're smoking weed that is high in 05:33.033 --> 05:37.266 align:left position:0%,start line:73.33% size:100% THC, the odds of developing a psychotic disorder are higher than if you're smoking weed that's 05:37.266 --> 05:39.133 align:left position:25%,start line:93.33% size:75% low in THC. 05:39.133 --> 05:43.000 align:left position:0%,start line:80% size:100% There is a lot of compelling evidence, but it's not necessarily final. 05:43.000 --> 05:48.000 align:left position:0%,start line:80% size:100% MILES O'BRIEN: They're seeking clues by studying the way our nervous system interacts with 05:48.600 --> 05:50.600 align:left position:25%,start line:93.33% size:75% cannabis. 05:50.600 --> 05:54.266 align:left position:0%,start line:80% size:100% The internal wiring that regulates our perceptions and thoughts is not continuous. 05:55.700 --> 05:59.400 align:left position:0%,start line:86.67% size:100% The nerve ends are called neurons, the gaps synapses. 06:01.400 --> 06:04.700 align:left position:0%,start line:80% size:100% The electrical current is transmitted across the synapses by chemical messengers called 06:05.633 --> 06:08.200 align:left position:12.5%,start line:93.33% size:87.5% neurotransmitters. 06:08.200 --> 06:12.033 align:left position:0%,start line:73.33% size:100% Our bodies naturally produce cannabinoids to help regulate the flow of these neurotransmitters. 06:12.766 --> 06:15.233 align:left position:37.5%,start line:93.33% size:62.5% DR. 06:15.233 --> 06:17.133 align:left position:0%,start line:73.33% size:100% DOST ONGUR: So, when somebody smokes cannabis, you are actually introducing chemicals that 06:17.133 --> 06:19.633 align:left position:0%,start line:86.67% size:100% can hijack that system that's controlling brain chemistry. 06:19.633 --> 06:24.633 align:left position:12.5%,start line:73.33% size:87.5% It appears that, during some critical period in brain development, cannabis has this effect 06:26.966 --> 06:29.400 align:left position:0%,start line:73.33% size:100% on the brain that actually disrupts normal functioning and predisposes people to a psychotic 06:29.400 --> 06:33.066 align:left position:0%,start line:86.67% size:100% disorder, whereas, in your 30s, it doesn't have the same effect. 06:33.066 --> 06:37.966 align:left position:0%,start line:80% size:100% MILES O'BRIEN: In all of this research, it's difficult, if not impossible, to tease apart 06:37.966 --> 06:39.966 align:left position:12.5%,start line:93.33% size:87.5% cause and effect. 06:39.966 --> 06:44.800 align:left position:0%,start line:80% size:100% Does cannabis trigger these disorders, or do people with these problems gravitate toward 06:44.800 --> 06:46.900 align:left position:25%,start line:93.33% size:75% the drug? 06:46.900 --> 06:51.033 align:left position:0%,start line:80% size:100% And no one has taken a look at the implications of long-term recreational cannabis use on 06:51.900 --> 06:53.966 align:left position:0%,start line:93.33% size:100% the fully formed adult brain. 06:53.966 --> 06:58.866 align:left position:0%,start line:80% size:100% But, recently, Staci Gruber has taken a look at medical marijuana among adults. 06:59.933 --> 07:01.066 align:left position:12.5%,start line:86.67% size:87.5% And she has some surprising conclusions. 07:01.066 --> 07:03.233 align:left position:37.5%,start line:93.33% size:62.5% DR. 07:03.233 --> 07:05.733 align:left position:12.5%,start line:73.33% size:87.5% STACI GRUBER: We're seeing improvements in cognitive performance, specifically on tasks 07:05.733 --> 07:08.266 align:left position:0%,start line:93.33% size:100% requiring executive function. 07:08.266 --> 07:11.766 align:left position:0%,start line:73.33% size:100% We're also seeing improvements in clinical state, so significantly lower levels of depressive 07:11.766 --> 07:13.866 align:left position:12.5%,start line:86.67% size:87.5% symptoms after only three months. 07:13.866 --> 07:18.333 align:left position:12.5%,start line:73.33% size:87.5% And, really important, we have seen some very striking decreases in the use of conventional 07:18.333 --> 07:20.433 align:left position:25%,start line:93.33% size:75% medications. 07:20.433 --> 07:23.666 align:left position:0%,start line:80% size:100% MILES O'BRIEN: Benefits, as opposed to the detriments she has documented in young people 07:23.666 --> 07:27.966 align:left position:12.5%,start line:86.67% size:87.5% using pot heavily to just get high. 07:27.966 --> 07:30.833 align:left position:0%,start line:86.67% size:100% Steve Mandile is a regular medical marijuana user. 07:30.833 --> 07:32.866 align:left position:0%,start line:86.67% size:100% STEPHEN MANDILE, Medical Marijuana User: Much better. 07:32.866 --> 07:37.466 align:left position:0%,start line:80% size:100% MILES O'BRIEN: In 2004, while serving in the Army in Iraq, he got in an accident that left 07:39.466 --> 07:43.300 align:left position:0%,start line:80% size:100% him with an excruciating back injury and a long list of prescription painkillers. 07:43.300 --> 07:48.300 align:left position:0%,start line:80% size:100% STEVE MANDILE: Over a 10-year period, I had taken 57 different medications, nine different 07:48.933 --> 07:50.433 align:left position:37.5%,start line:93.33% size:62.5% opioids. 07:50.433 --> 07:52.900 align:left position:0%,start line:86.67% size:100% I believe, in 2009, I was just getting on to fentanyl. 07:52.900 --> 07:57.900 align:left position:0%,start line:80% size:100% I did six years on fentanyl, oxycodone for my chronic pain and then breakthrough pain. 08:00.000 --> 08:03.733 align:left position:12.5%,start line:73.33% size:87.5% MILES O'BRIEN: It was a struggle, but he finally weaned himself off of opioids, and now relies 08:05.566 --> 08:09.733 align:left position:0%,start line:80% size:100% mostly on medical marijuana, which, unlike those prescription painkillers, has never 08:10.600 --> 08:13.400 align:left position:0%,start line:93.33% size:100% caused an overdose death. 08:13.400 --> 08:18.400 align:left position:12.5%,start line:73.33% size:87.5% But government studies show 9 percent of those who use marijuana will become dependent on 08:20.300 --> 08:23.666 align:left position:0%,start line:80% size:100% the drug, much better than alcohol, at about 23 percent, or cocaine, 21 percent. 08:25.700 --> 08:28.533 align:left position:12.5%,start line:93.33% size:87.5% But it is not risk-free. 08:28.533 --> 08:33.533 align:left position:12.5%,start line:73.33% size:87.5% Steve Mandile is well aware of all of this, but remains convinced cannabis has made nearly 08:34.400 --> 08:36.066 align:left position:0%,start line:93.33% size:100% every aspect of his life better. 08:36.066 --> 08:39.566 align:left position:0%,start line:86.67% size:100% STEVE MANDILE: Every person suffering deserves a choice. 08:39.566 --> 08:44.566 align:left position:0%,start line:80% size:100% And let's stop looking at this as the initial idea back in the '30s, where this is something 08:45.733 --> 08:47.566 align:left position:12.5%,start line:86.67% size:87.5% that's terrible, it's going to ruin the world. 08:47.566 --> 08:49.233 align:left position:0%,start line:93.33% size:100% Let's get past all the stigma. 08:49.233 --> 08:51.633 align:left position:0%,start line:93.33% size:100% Let's focus on the facts. 08:51.633 --> 08:56.366 align:left position:0%,start line:73.33% size:100% MILES O'BRIEN: Once vilified, but now moving into the mainstream, cannabis is neither totally 08:57.600 --> 09:00.800 align:left position:0%,start line:93.33% size:100% bad, nor completely benign. 09:00.800 --> 09:05.766 align:left position:12.5%,start line:80% size:87.5% It turns out weed is as much about shades of gray as it is green. 09:07.166 --> 09:10.033 align:left position:0%,start line:86.67% size:100% For the "PBS NewsHour," I'm Miles O'Brien in Boston.