Ask anyone who began using marijuana during the marvelous sixties and they will tell you that smoking marijuana has no long term health implications. Nor does it lead to addiction and use of more potent drugs. They will tell you that they don’t know of any of their old friends, even the most aggressive users, who became crack or heroin addicts. That’s because those who did are dead (mostly musicians), homeless, or NOCD.
There is an old theory called the “gateway” theory that maintains that marijuana is a step toward harder drugs. According to Robin Murray, a competing theory was referred to as the “correlated vulnerabilities” theory, meaning that some people have a predisposition to drug usage that could be mediated by a risk-taking person as found in a study by Golub and Johnson. (Murray 2007, Golub 2001) Murray states that the latter theory has been favored for many years, but the gateway theory has been recently revived. (Fergusson). “Regular or heavy cannabis use was associated with an increased risk of using other illicit drugs, abusing or becoming dependent upon other illicit drugs, and using a wider variety of other illicit drugs . . . The findings may support a general causal model such as the cannabis gateway hypothesis, but the actual causal mechanisms underlying such a gateway, and the extent to which these causal mechanisms are direct or indirect, remain unclear.” (Fergusson)
These findings were supported by Lynskey who studied drug use in twin pairs that were discordant for use. Marijuana use by subjects prior to 17 resulted in two to five times greater likelihood for “subsequent other drug use, and drug and alcohol dependence.” (Lynskey) Animal studies support the gateway theory showing developmental plasticity of the reward system. Murray concludes: “whether early use of cannabis increases the risk of subsequent use of hard drugs remains highly contentious. Most cannabis users do not escalate to the use of heroin or cocaine, but recent studies have put the gateway theory back into contention.”
Gateway conduct results from a phenomenon called anhedonia defined as: a psychological condition characterized by inability to experience pleasure in normally pleasurable acts. In other words, the user is no longer getting a kick out of the lesser drug and seeks a stronger hit to obtain a high.
Anhedonia, like so many other psychological hypotheses, is frustrating for lack of consensus on what the term means, if anything. Here is Wikipedia: “While earlier definitions of anhedonia emphasized  the inability to experience pleasure,  anhedonia is used by researchers to refer to reduced motivation,  reduced anticipatory pleasure (wanting),  reduced consummatory pleasure (liking), and  deficits in reinforcement learning.” The DSM-V defines the term as: “a component of depressive disorders, substance related disorders, psychotic disorders, and personality disorders, where it is defined by either a reduced ability to experience pleasure, or a diminished interest in engaging in pleasurable activities.” As stated in an article on a recovery website, citing studies: “The evidence of anhedonia’s link to addiction is well documented. . . . It is likely anhedonia can persist longer than a year, but the duration of the condition has not been investigated.” (Sindewald)
While the research is incomplete, there is a relationship between the gateway theory and anhedonia. If as a result of drug use, the pleasure extracted from the experience decreases over time, the “wanting” for a more pleasurable experience induces a desire for a stronger drug. Or, conversely, there is a diminished interest in engaging in this form of pleasurable activity, the “high,” and the user is no longer interested in anything – they are amotivational. These alternatives must be the result of differences in the users. There is no other explanation. But in either event society has a problem – addiction and its consequences, or a lack of motivation. In the former case the result is a wide range of psychopharmacological and psychological treatments. In the latter case, we have a passivated segment of the population about which society cannot, or cares not, to offer help. The soma world.
A test was conducted on rats by Dr. Winstanley, a psychology professor at the University of British Columbia and her team to confirm an interesting hypothesis. Does THC impair long-term success, such as the willingness to exert cognitive effort for greater rewards. Second, could CBD attenuate such undesirable results. As a result of the use of rats by psychologists and others to test hypotheses of various sorts, there are standardized tests, one having been developed for rats called the rat cognitive effort task (rCET). This test does not measure the performance of the task but rather the organism’s willingness to perform the task. So if the task is easily performed it will be readily chosen except that the reward is made small whereas a high payoff can be achieved only if a more difficult task is undertaken. By varying the amount of THC, the amount of CBD, if any, and various combinations, the authors concluded that THC selectively impairs motivation to go for the big reward/big effort. And note that there is no impairment of the rat’s ability to complete the experiment. These are the “slacker” rats. CBD does not affect choice, but if combined with THC lessens the dysfunction.
In a 2016 study and test, 17 human subjects were given THC and CBD as well as placebos. (Lawn) They were tested using the Effort Expenditure for Rewards Task (EEfRT) and a second test called a Probabilistic Reward Task (PRT) given to dependent marijuana users and other users but who were not dependent. In the former, Cann-CBD reduced the likelihood of high-effort choices relative to a placebo. In the second test, the dependent users did as well as the casual users on the EEfRT test but a weaker response bias on the PRT. The researchers concluded: “Cannabis acutely induced a transient amotivational state.” But “cannabis dependence was associated with preserved motivation alongside impaired reward learning.”
To be continued