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Does Long-Term Cannabis Use Stifle Motivation?

Habitual use of marijuana is linked to lower dopamine levels.

Researchers have found that levels of dopamine are lower in long-term cannabis smokers and those who began using the drug at a younger age. Lower dopamine in a part of the brain called the striatum is linked to less ambition and motivation at a neuronal level. I have written extensively about dopamine and endocannabinoids (self-produced cannabis) in The Athlete’s Way over the years.

The new study, released on July 1, 2013, was conducted by scientists at Imperial College London, UCL and King's College London. The researchers found that long-term cannabis users tend to produce less dopamine, a neurochemical directly linked to motivation and reward. Using PET brain imaging, the researchers found that dopamine levels in a part of the brain called the striatum were lowest in people who smoke more cannabis and those who began smoking marijuana at a younger age.

The findings suggest why "stoners" are stereotypically viewed as lacking the motivation to work hard to pursue their dreams or to be ambitious. Do you think that pot makes people lazy? Have you had personal experience with the phenomenon of cannabis-induced “amotivational syndrome”—also known as being a slacker?

There is a strong link between dopamine and the CB-1 and CB-2 cannabinoid receptors of the brain. Any exogenous substance, like cannabis, hijacks the pre-existing receptors for the endogenously produced neurochemical. Contrary to popular belief, endocannabinoids are more strongly linked to "runner’s high" than endorphins.

Dopamine has long been linked to reward-driven behavior like achieving any type of goal in life or sport. You can increase the levels of both cannabinoids and dopamine through lifestyle choices without drugs. Setting goals and achieving them is the best way to keep the dopamine pumping. Regular aerobic exercise is the best way to get the endocannabinoids pumping.

Cannabis makes you more prone to “amotivational syndrome,” but less prone to psychosis.

All of the cannabis users in the study had experienced some psychotic-like symptoms while smoking marijuana. Researchers describe these symptoms as “experiencing strange sensations or having bizarre thoughts like feeling as though they are being threatened by an unknown force.” I call this having a “bad trip.”

The London researchers studied the level of dopamine production in the striatum of 19 regular cannabis users and 19 non-users of matching gender and age. The cannabis users chosen for the study started experimenting with cannabis between the ages of 12 and 18.

The researchers found that the younger someone was when he or she started smoking pot the lower the current levels of dopamine. Also, dopamine was lower in those who smoked more cannabis and had higher levels of THC in their bodies. The researchers conclude that these findings suggest that cannabis use may be the cause of the difference in dopamine levels.

The lowest dopamine levels were seen in users who meet a diagnostic criteria for cannabis addiction. The link to lower dopamine could be used as a new measure for what degree someone is addicted to—or abusing—cannabis. The good news from the study is that these results are most likely reversible. Other researchers have studied the dopamine release in former long-term cannabis users and found no differences with people who never abused cannabis.

Other good news from the study was that previous research had shown that cannabis users have a higher risk of mental illnesses that involve repeated episodes of psychosis, such as schizophrenia. This study found that smoking marijuana actually lowered the odds of having repeated episodes of psychosis. According to lead author Dr. Michael Bloomfield, "It has been assumed that cannabis increases the risk of schizophrenia by inducing the same effects on the dopamine system that we see in schizophrenia, but this hasn't been studied in active cannabis users until now.”

Bloomfield adds, "The results weren't what we expected, but they tie in with previous research on addiction, which has found that substance abusers—people who are dependent on cocaine or amphetamine, for example—have altered dopamine systems."

"Although we only looked at cannabis users who have had psychotic-like experiences while using the drug, we think the findings would apply to cannabis users in general, since we didn't see a stronger effect in the subjects who have more psychotic-like symptoms,” Bloomfield says. The researchers believe that more research needs to be done before drawing final conclusions.

Conclusion: Have you ever smoked pot? Does cannabis make you less motivated?

Do you smoke pot? If so, how often? What age were you when you started smoking marijuana? Do you find that cannabis makes you more productive and creative, or less? Does smoking pot make you paranoid? Different friends of mine seem to have a wide range of responses to cannabis.

I had a classic bad trip on psychedelic mushrooms when I was in high school. I felt like the blueprint of my brain was being permanently reconfigured and the architecture of my mind was being rearranged. It was terrifying. The psilocybin opened doors of perception that should stay closed, and closed windows to perceptions of reality that need to stay open.

William Blake once said, “If the doors of perception were cleansed, everything would appear to man as it is, infinite. For man has closed himself up, till he sees all things thro' narrow chinks of his cavern.” Some people—like Jim Morrison of the DOORS—used this Blake quotation to romanticize being high or tripping. For me, having a bad trip was the most harrowing experience of my life. I smoked pot once after that and had a flashback. Needless to say, I was so spooked by the experience that I haven’t smoked pot since 1983.

Bloomfield concludes that the 'amotivational syndrome,' which he describes in cannabis users, is linked to lower levels of dopamine, but acknowledges that whether such a syndrome exists is still controversial. If you or someone you know is a long-term pot smoker, would you agree or disagree with the scientific findings that abusing cannabis stifles motivation?

For more on the power of self-produced neurochemicals associated with feeling good and staying motivated please check out my Psychology Today blog The Neurochemicals of Happiness.

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