Is marijuana bad for your brain? - Anees Bahji
-
0:06 - 0:08In 1970,
-
0:08 - 0:13marijuana was classified
as a schedule 1 drug in the United States: -
0:13 - 0:16the strictest designation possible,
-
0:16 - 0:21meaning it was completely illegal
and had no recognized medical uses. -
0:21 - 0:24For decades, this view persisted
-
0:24 - 0:29and set back research
on the drug's mechanisms and effects. -
0:29 - 0:33Today, marijuana’s therapeutic benefits
are widely acknowledged, -
0:33 - 0:36and some nations
have legalized medical use -
0:36 - 0:38or are moving in that direction.
-
0:38 - 0:42But a growing recognition
for marijuana’s medical value -
0:42 - 0:44doesn’t answer the question:
-
0:44 - 0:49is recreational marijuana use
bad for your brain? -
0:49 - 0:53Marijuana acts
on the body’s cannabinoid system, -
0:53 - 0:56which has receptors
all over the brain and body. -
0:56 - 1:01Molecules native to the body,
called endocannabinoids, -
1:01 - 1:04also act on these receptors.
-
1:04 - 1:07We don’t totally understand
the cannabinoid system, -
1:07 - 1:12but it has one feature
that provides a big clue to its function. -
1:12 - 1:16Most neurotransmitters
travel from one neuron to the next -
1:16 - 1:19through a synapse to propagate a message.
-
1:19 - 1:23But endocannabinoids
travel in the opposite direction. -
1:23 - 1:27When a message passes
from the one neuron to the next, -
1:27 - 1:31the receiving neuron
releases endocannabinoids. -
1:31 - 1:34Those endocannabinoids
travel backward -
1:34 - 1:36to influence the sending neuron—
-
1:36 - 1:40essentially giving it feedback
from the receiving neuron. -
1:40 - 1:44This leads scientists
to believe that the endocannabinoid system -
1:44 - 1:48serves primarily
to modulate other kinds of signals— -
1:48 - 1:52amplifying some and diminishing others.
-
1:52 - 1:57Feedback from endocannabinoids
slows down rates of neural signaling. -
1:57 - 1:59That doesn’t necessarily mean
-
1:59 - 2:02it slows down behavior
or perception, though. -
2:02 - 2:06For example,
slowing down a signal that inhibits smell -
2:06 - 2:10could actually make smells more intense.
-
2:10 - 2:13Marijuana contains
two main active compounds, -
2:13 - 2:22tetrahydrocannabinol or THC,
and cannabidiol, or CBD. -
2:22 - 2:28THC is thought to be primarily responsible
for marijuana’s psychoactive effects -
2:28 - 2:30on behavior, cognition, and perception,
-
2:30 - 2:35while CBD is responsible
for the non-psychoactive effects. -
2:35 - 2:38Like endocannabinoids,
-
2:38 - 2:43THC slows down signaling
by binding to cannabinoid receptors. -
2:43 - 2:47But it binds to receptors
all over this sprawling, diffuse system -
2:47 - 2:48at once,
-
2:48 - 2:52whereas endocannabinoids
are released in a specific place -
2:52 - 2:55in response to a specific stimulus.
-
2:55 - 2:58This widespread activity
coupled with the fact -
2:58 - 3:02that the cannabinoid system
indirectly affects many other systems, -
3:02 - 3:07means that each person’s
particular brain chemistry, genetics, -
3:07 - 3:09and previous life experience
-
3:09 - 3:12largely determine
how they experience the drug. -
3:12 - 3:16That’s true much more so with marijuana
than with other drugs -
3:16 - 3:21that produce their effects
through one or a few specific pathways. -
3:21 - 3:26So the harmful effects, if any,
vary considerably from person to person. -
3:26 - 3:29And while we don’t know
how exactly how marijuana -
3:29 - 3:31produces specific harmful effects,
-
3:31 - 3:35there are clear risk factors
that can increase peoples’ likelihood -
3:35 - 3:37of experiencing them.
-
3:37 - 3:40The clearest risk factor is age.
-
3:40 - 3:42In people younger than 25,
-
3:42 - 3:46cannabinoid receptors
are more concentrated in the white matter -
3:46 - 3:49than in people over 25.
-
3:49 - 3:52The white matter
is involved in communication, -
3:52 - 3:55learning, memory, and emotions.
-
3:55 - 3:56Frequent marijuana use
-
3:56 - 3:59can disrupt the development
of white matter tracts, -
3:59 - 4:03and also affect the brain’s ability
to grow new connections. -
4:03 - 4:08This may damage long-term learning ability
and problem solving. -
4:08 - 4:11For now, it’s unclear
how severe this damage can be -
4:11 - 4:13or whether it’s reversible.
-
4:13 - 4:15And even among young people,
-
4:15 - 4:18the risk is higher the younger someone is—
-
4:18 - 4:23much higher for a 15 year old
than a 22 year old, for instance. -
4:23 - 4:27Marijuana can also cause hallucinations
or paranoid delusions. -
4:27 - 4:30Known as marijuana-induced psychosis,
-
4:30 - 4:34these symptoms usually subside
when a person stops using marijuana. -
4:34 - 4:37But in rare cases,
psychosis doesn’t subside, -
4:37 - 4:42instead unmasking
a persistent psychotic disorder. -
4:42 - 4:46A family history of psychotic disorders,
like schizophrenia, -
4:46 - 4:49is the clearest, though not the only,
risk factor for this effect. -
4:49 - 4:54Marijuana-induced psychosis
is also more common among young adults, -
4:54 - 4:56though it’s worth noting
that psychotic disorders -
4:56 - 4:59usually surface in this age range anyway.
-
4:59 - 5:03What’s unclear in these cases
is whether the psychotic disorder -
5:03 - 5:05would have appeared
without marijuana use— -
5:05 - 5:08whether marijuana use triggers it early,
-
5:08 - 5:12is a catalyst for a tipping point
that wouldn’t have been crossed otherwise, -
5:12 - 5:16or whether the reaction
to marijuana is merely an indication -
5:16 - 5:18of an underlying disorder.
-
5:18 - 5:23In all likelihood, marijuana’s role
varies from person to person. -
5:23 - 5:26At any age, as with many other drugs,
-
5:26 - 5:27the brain and body
-
5:27 - 5:31become less sensitive
to marijuana after repeated uses, -
5:31 - 5:35meaning it takes more
to achieve the same effects. -
5:35 - 5:38Fortunately, unlike many other drugs,
-
5:38 - 5:41there’s no risk of fatal overdose
from marijuana, -
5:41 - 5:44and even heavy use
doesn’t lead to debilitating -
5:44 - 5:48or life-threatening
withdrawal symptoms if use stops. -
5:48 - 5:52There are more subtle forms
of marijuana withdrawal, though, -
5:52 - 5:57including sleep disturbances,
irritability, and depressed mood, -
5:57 - 6:01which pass
within a few weeks of stopping use. -
6:01 - 6:03So is marijuana bad for your brain?
-
6:03 - 6:05It depends who you are.
-
6:05 - 6:09But while some risk factors
are easy to identify, -
6:09 - 6:11others aren’t well understood—
-
6:11 - 6:16which means there’s still some possibility
of experiencing negative effects, -
6:16 - 6:20even if you don’t have
any of the known risk factors.
- Title:
- Is marijuana bad for your brain? - Anees Bahji
- Speaker:
- Anees Bahji
- Description:
-
View full lesson: https://ed.ted.com/lessons/is-marijuana-bad-for-your-brain-anees-bahji
In 1970, marijuana was classified as a schedule 1 drug in the United States: the strictest designation possible, meaning it was completely illegal and had no recognized medical uses. Today, marijuana's therapeutic benefits are widely acknowledged, but a growing recognition for its medical value doesn't answer the question: is recreational marijuana use bad for your brain? Anees Bahji investigates.
Lesson by Anees Bahji, directed by Anton Bogaty.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 06:21
lauren mcalpine edited English subtitles for Is marijuana bad for your brain? | ||
Elise Haadsma approved English subtitles for Is marijuana bad for your brain? | ||
Elise Haadsma accepted English subtitles for Is marijuana bad for your brain? | ||
lauren mcalpine edited English subtitles for Is marijuana bad for your brain? |