Pubdate: Thu, 17 May 2018
Source: National Post (Canada)
Copyright: 2018 Canwest Publishing Inc.
Author: Sharon Kirkey


Researchers have long been intrigued by the intoxicating effects of
the world's most popular illicit drug. Here's how pot affects your
body and mind

When neurologist Frances Ames began testing the effects of a single
dose of cannabis sativa on a group of her medical colleagues who were,
on the whole, "articulate and fairly stable people," the onset of
abnormal sensations "was always abrupt and immediate." One was
sustained hilarity. "The whole idea of the experiment," Ames reported
in 1958 in the Journal of Mental Science, "would suddenly seem
enormously amusing." Researchers have long been intrigued by the
intoxicating effects of the world's most popular illicit drug. Here's
everything you need to know about how pot affects your body and mind.

First, a brief bit of biology:

The body has an endogenous, or natural cannabinoid system. Endogenous
cannabinoids play a role in the brain's normal functioning, shuttling
messages from one nerve cell to another. Not only the brain, but the
spleen, uterus, testicles and other tissue have cannabinoid receptors.
THC, the principal active component of weed, mimics a natural
cannabinoid called anandamide, the "bliss molecule." When smoked, THC
quickly diffuses to the brain. "The consumption of cannabis causes a
particular combination of relaxation and euphoria, commonly referred
to as a 'high'," a committee of the U.S. National Academies of
Sciences, Engineering and Medicine dryly noted last year in its
exhaustive review of the health effects of cannabis. With very high
levels of THC, things aren't always so pretty.

Marijuana makes us laugh and scarf snacks

The academies report notes how, during acute cannabis intoxication,
one's "sociability" and appetite for sweet and fatty foods is
heightened. "Munchies" may be driven by THC interfering with neurons
in the brain normally involved in suppressing appetite, according to a
study in Nature.

When researchers injected mice with THC, the neurons responsible for
shutting down eating were suddenly fired up. "It's like pressing a
car's brakes and accelerating instead," said lead author Tamas
Horvath. The pathological laughter is harder to explain, although
studies have suggested it may have to do with marijuana's
anti-depressant-like effects, as well as the drug's ability to
increase blood volume in the right frontal and left temporal lobes in
the cerebral cortex, the brain areas thought associated with "mirth
and laughter."

Pot increases the noise in your brain

In 2015, Yale School of Medicine researchers reported THC increased
random "corticol noise" in the brains of healthy volunteers. Corticol
noise is a kind of random activity in electrical circuits in the brain
(think of the noise of a crowded room versus a single voice). This may
explain THC's sometimes psychosis-like effects. Some people, for
reasons no one fully understands, experience a "robust syndrome" that
mimics some aspects of schizophrenia, said Dr. Deepak Cyril D'Souza, a
professor of psychiatry at Yale and the study's senior author. They
have symptoms of paranoia and hear voices. In the Yale study,
volunteers given intravenous injections of THC showed an increase in
neural noise on an EEG. The findings may add to other studies that
suggest heavy pot use might precipitate or hasten schizophrenia,
especially if used in early or mid-adolescence. The higher the use,
the greater the risk.

Weed plays with your memory

In 2015, a team of Spanish researchers Spanish researchers reported
heavy pot users appear more vulnerable to "memory distortions,"
possibly due to decreased activity in the hippocampus, the region
associated with memory. The effects were seen even though the pot
users had not consumed marijuana in the month leading up to the study,
"suggesting a long-lasting compromise of memory and cognitive control
mechanisms involved in reality monitoring." As UPI summarized it:
"Stoners don't make for good eyewitnesses." The study also suggested
that heavy pot users may remember things that never actually happened.
The study involved 16 people who had used cannabis an average of
42,000 times over 21 years.

Pot makes you a slacker. Temporarily

Cannabis dampens neurons involved in motor response and excitation in
various brain regions, "your kind of go-go response," said Will Lawn,
of University College London's clinical pharmacology unit. He was the
lead author of a study published two years ago where researchers asked
volunteers to inhale pot vapour through a balloon on one occasion, and
a placebo vapour on another. Then participants were given the option
of completing a "low-effort" or "high-effort" task for cash. They
could hit a space bar with the little finger of their non-dominant
hand 30 times in 10 seconds for 50p (about 90 cents); or press it 100
times in 21 seconds to win up to two pounds (about $3.60). Volunteers
on the placebo "pot" chose the high-effort option, on average, 50 per
cent of the time vs. 42 per cent of those high on real pot. However,
in a separate study, the researchers saw no differences in the
willingness of long-term cannabis users to work for money when they
weren't stoned. In other words, cannabis use does not effect
motivation when people are sober, Lawn said. Others report that
long-term use of marijuana is associated with cognitive impairment,
particularly in learning and remembering new things - but maybe not so
much with older people. A study last year found that a low dose of THC
reversed age-related declines in brain function in old mice.

Where did the time go?

Even low doses of THC can make time seem to slow down. The effect
disappears within a few hours, and it appears to be blunted in chronic
(two to three times a week or more) users. One 2013 study found that
even exceedingly low doses of THC can increase people's "internal
clock speed." In that study, THC was administered intravenously to 44
people. Regardless of dose, volunteers overestimated how much time had
passed, though frequent users showed no differences. Ames, the South
African neuroscientist and psychiatrist, noted that, when stoned, her
subjects reported that events that occurred immediately after each
other "seemed separated by an eternity of time." There's no time
centre in the brain, per se, said Dalhousie University professor of
psychiatry Phil Tibbo. "But cannabis does effect some of those
cognitive domains like attention, concentration, memory. That's
probably what's influencing and resulting in, for some people, feeling
time's a bit different."

Marijuana makes babies trickier

Heavy pot use might lower a man's reproductive potential by affecting
the morphology - size and shape - of his sperm. A study published in
the journal Human Reproduction found males under 30 with less than
four-per-cent normal sperm were nearly twice as likely to have used
cannabis in the last three months. No similar associations were found
with BMI, type of underwear, smoking, alcohol consumption or having a
history of the mumps. Sperm with morphology issues are generally lousy
swimmers, crawling and crashing head-on into the walls of the female
reproductive tract in their frantic swim to fertilize an egg. Chronic
cannabis use has also been linked to decreased libido in men. For
women, some research suggests cannabis suppresses ovulation. It's also
been linked to early pregnancy loss and low-birthweight babies if used
at the time of conception, or during pregnancy. Emerging animal data
also suggests using pot during pregnancy impairs fetal brain

The good and the bad:

According to the academies of sciences review, the best evidence
suggests smoking weed doesn't increase the risk for lung, head or neck
cancers in adults, though there is "modest" evidence linking it to a
subtype of testicular cancer. The evidence is "unclear" as to whether
cannabis increases the risk of heart attack or stroke, but there's
some evidence it has anti-inflammatory effects. Using pot before
driving increases the risk of being in a crash but it doesn't appear
to increase the likelihood of developing depression, anxiety or
post-traumatic stress disorder.

When do you know things are becoming problematic?

According to the fifth and latest edition of the Diagnostic and
Statistical Manual of Mental Disorders (DSM-5), psychiatry's official
catalogue of mental illness, individuals with "cannabis use disorder"
may spend many hours a day under the influence of pot. Other criteria
include spending a great deal of time obtaining, using or recovering
from the effects of cannabis and a need for markedly increased amounts
of the drug to achieve the desired effects. New to DSM-5 is "cannabis
withdrawal," caused by the abrupt cessation in heavy daily, or near
daily, pot use. Symptoms can include irritability, anger or
aggression, restlessness, sweating, fever, chills and hypersomnia.
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MAP posted-by: Matt