People have touted amotivation syndrome as a symptom of excessive cannabis use, but I have always had trouble with this concept. I have watched many adolescents abandon their normal pursuits after discovering cannabis, but no one has shown me how to measure motivated objectively.
The Gestalt therapist Fritz Perls was said to have asked people to demonstrate they were trying to drop a pillow. After multiple contortions, while still holding onto the pillow, it became apparent that motivation is an elusive concept, impossible to see or directly measure.
Instead of thinking in terms of amotivation, I consider the boredom and loss of interest in activities that characterize many regular users to be a failure to respond to novelty. When nothing is novel, people are less likely to be interested and feel motivated in any particular direction, except perhaps to use cannabis again.
In addition, when people enter Cannabis Culture, they often begin looking at the world through a different lens. Changing values and aspirations can withdraw interest from pursuits that no longer hold the same meaning. [Excerpted from Marijuana on My Mind: The Science and Mystique of Cannabis]
A clever human study began changing my mind.1 A delayed monetary reward study asked college students to press a button when a stimulus appeared on the screen. They were promised either $0.20 or $5.00 after the test, depending on their performance. MRI of the reward center was conducted during the test, administered at ages 20, 22, and 24.
Over the four years, those whose cannabis use increased the most were found to have decreasing activation of the reward center in anticipation of financial reward. This interesting research suggests that, as cannabis alters the brain’s reward center, regular users begin to anticipate less reward from non-cannabis sources.
Cannabis alters the structure and function of reward circuitry to shift attention and priorities away from previous targets and toward cannabis. This is a prime example of the brain being hijacked; the promise of financial gain began stimulating less activity in their reward center.
This study shows how the reward for non-cannabis events is lessened as the reward for cannabis increases. Perhaps the couchlock seen in the heaviest cannabis users is not simply a matter of decreasedspontaneous motor activity but also results from the brain’s inability to signal reinforcing rewards for anything not cannabis-related. Motivation depends upon the anticipation of reward and anticipating reward from anything not involving cannabis.
I was familiar with research showing how rats given THC became “slackers,” more likely to choose low-effort/low-reward tasks instead of the high-effort/high-reward tasks they previously pursued.
Now an article in the February 1, 2022 issue of Psychopharmacology reports a study that reproduces the same “slacker” results in humans.2 This study gave women oral placebo, or either 7.5 or 15 mg of THC, and asked them to choose either a low-effort/low-reward task (pressing a button 30 times in seven seconds with their dominant index finger) or a high- effort/high-reward task (pressing a button 100 times in 21 seconds with their non-dominant pinky finger).
The amount of monetary reward depends on the difficulty of each task. After the higher dose of THC, the women were 55 percent less likely to choose the high-effort/high-reward task and 74 percent less likely to complete the task they chose. However, slowing of motor speed was partially responsible for decreased task completion.
The most striking result was THC’s impact on choices the women made, ie, lower effort to achieve lower reward compared to their choices after receiving a placebo. Whether this resulted from motivation or from anticipating failure to meet the higher demands of the high-effort task is not entirely clear. Still, the result is the same – the women aimed toward lower achievement and lower reward.
One interesting wrinkle should be noted. An earlier study using vaporized cannabis with and without CBD found that CBD moderately attenuated THC’s lowering motivation to choose high-effort/high-reward tasks.3
It is safe to conclude that an acute dose of cannabis, especially high THC cannabis, temporarily reduces the willingness to choose hard tasks. For the occasional cannabis user, this would be of little consequence. Whether regular use leads to decreased motivation is less clear and much harder to study.
On the other hand, regular use does mean individuals are repeatedly experiencing the acute impact of THC and therefore are likely choosing low-effort tasks much of the time.
All individuals are different in their response to cannabis, but all regular users should be aware of the risk of what can now rightfully be called “amotivational syndrome.”