Behavioral Effects

Cannabis produces intoxication in humans that is often labeled as pleasurable and, by definition, rewarding. The subjective effects include euphoria and mood swings characterized by initial feelings of “happiness,” sudden talkativeness, a dreaming or lolling state, and general activation and hyporeactivity. Users report feeling fuzzy, dizzy, sleepy, and in a dream-like state. They also feel more friendly toward others and find more pleasure in the company of others. In a group setting, smoking cannabis produces talkativeness among people, with contagious laughing and joking and a particularly high-pitched giggly laughter. In studies of the self-reported effects of cannabis in regular human cannabis users, both in naturalistic studies and laboratory settings, the most frequently reported effect of cannabis was relaxation. Enhanced mood (happiness or laughing more), sensory alterations, enhanced appetite, and greater insight/thinking also ranked high (Table 8.6). Large individual differences have been observed in the response to cannabis, and the effects are heavily influenced by a person’s expectations. Decreased talkativeness and decreased sociability are often reported, and these effects may be dose-related and more likely to occur at higher doses. A characteristic effect of marijuana intoxication compared with alcohol intoxication is being “less noisy and boisterous at parties than when drunk or tipsy on alcohol” (Tart CT. On Being Stoned: A Psychological Study of Marijuana Intoxication. Science and Behavior Books, Palo Alto CA, 1971). Sociability can go either way, with self-reports of “I become more sociable” (more likely at lower levels of intoxication) and “I become less sociable” (at higher levels of intoxication; Figure 8.5). In a human laboratory study, in which subjects smoked at least four times per week (average 6.6 times per week) while they participated in a 16 day residential study, smoking marijuana cigarettes varied as a function of Δ9-THC content. Marijuana cigarettes with Δ9-THC concentrations of 2.2% and 3.9% were smoked more than placebo cigarettes. Subjects reported significant increases in ratings of high, stimulated, and good drug effect, but measures of forgetful and can’t concentrate also increased, and performance decreased on a digit-symbol substitution task, divided attention task, rapid information task, and mathematics task. Some of these effects were greater in the subjects who smoked marijuana cigarettes with 3.9% vs. 2.2% Δ9-THC content.


Ten Most Frequently Reported Effects of Marijuana Intoxication (Based on Open-Ended Questions)

Taken with permission from Green B, Kavanagh D, Young R. Being stoned: a review of self-reported cannabis effects. Drug and Alcohol Review, 2003, (22), 453–460.

Human subjects may have a form of disinhibition, with an inclination to increase motor activity and behave impulsively. However, paradoxically, even the simplest tasks appear to require enormous effort. Users generally seek situations where no physical effort is required. Thus, an individual may be disinhibited, but incoordination and clumsiness prevent the individual from attempting many activities. Following is an early clinical description of acute intoxication:

“Walking becomes effortless. The paresthesias and changes in bodily sensations help to give an astounding feeling of lightness to the limbs and body. Elation continues: he laughs uncontrollably and explosively for brief periods of time without at times the slightest provocation: if there is a reason it quickly fades, the point of the joke is lost immediately. Speech is rapid, flighty, the subject has the impression that his conversation is witty, brilliant; ideas flow quickly.”

(Bromberg W. Marihuana intoxication: a clinical study of Cannabis sativa intoxication. American Journal of Psychiatry, 1934, (91), 303–330.)

Psychedelic-like effects are also associated with marijuana intoxication. Subjects report an increased sensitivity to sound and a keener appreciation of rhythm and timing. The perception of time often slows, with an exaggeration of the sense of time. The perception of space may broaden, and objects that are near may appear distant. Visual hallucinations, similar to psychedelics such as lysergic acid diethylamide, can include illusionary transformations of the outer world. Flashes of light may be seen, or amorphous forms of vivid color may evolve into geometric figures, shapes, or faces. The depth of color is striking, with an apparent increase in auditory faculties (Table 8.7). Users may also have subjective feelings of unreality that border on depersonalization, with various sensations of lightness or heaviness in the body and a sensation of floating in air or walking on waves. One adolescent user reported:

FIGURE 8.5 Effect of level of marijuana intoxication on sociability. “I become more sociable” is a common effect, but its converse, “I become less sociable; I want to be by myself,” is just as common. The latter occurs at higher levels of intoxication than the former. At a party, for instance, people sitting by themselves may often be more intoxicated than the people who are conversing. The intoxication level data will not always add up to 100% because of variable numbers of respondents who skip various questions or because of rounding errors. In interpreting the graph, notice that the percentage of users plotted at each level is the percentage of people who indicated that level as their minimal level of intoxication for experiencing that particular effect. A drop in the curve with an increasing minimal level of intoxication does not mean that fewer users experience that effect at higher levels, but rather that fewer give a higher level as their minimal level for experiencing that effect. These data suggest that greater intoxication is associated with a greater likelihood that one will not socially interact. Conversely, less intoxication is associated with a greater likelihood that the person will socially interact. [Taken with permission from Tart CT. On Being Stoned: A Psychological Study of Marijuana Intoxication. Science and Behavior Books, Palo Alto CA, 1971.]

Table 8.7

Behavioral Effects of Marijuana Intoxication

[Taken with permission from Koob GF, Le Moal M. Neurobiology of Addiction. Academic Press, London, 2006.]

“Man, when I’m up on the weed, I’m really livin’. I float up and up and up until I’m miles above the Earth. Then, Baby, I begin to come apart. My fingers leave my hands, my hands leave my wrists, my arms and legs leave my body and I just flooooooat all over the universe.”

(Bloomquist ER. Marijuana: social benefit or social detriment? California Medicine. 1967, (106), 346–353.)

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