[MUSIC] This lesson will focus on several psychotropic effects of cannabis, including cannabis intoxication, relation to psychosis, and addiction. Common psychotropic effects of cannabis intoxication include induction of relaxed and dreamy state, loss of time perception, anxiety, and psychosis. The time frame for these cognitive effects may change so that acute residual and chronic effects may be reported. Several studies have shown that alterations in memory and attention can persist even after acute intoxication has resolved. In a study conducted in 2002, neuropsychological tests were administered to 77 heavy cannabis users who had smoked cannabis at least 5,000 times in their lives and to 87 control subjects who had smoked no more than 50 times in their lives. The heavy smokers showed deficits on memory of word lists on days zero, one and seven of a supervised abstinence period. By day 28 however, few significant differences were found between users and controls. A 2004 study examined pet scans which test activity in different brain regions during the iowa gambling task, a real time decision making simulation test. The study demonstrated a dose related association between increased cannabis used and lowered performance in the decision making task as well as altered brain activity measured by the pet scans. The authors concluded that very heavy cannabis users have persistent decision making deficits and alterations in brain activity. More specifically, heavy cannabis users can focus only on one immediate reinforcement aspect of a situation, such as getting high, while ignoring the negative consequences of such an act. The faulty decision making render the individual more prone to addictive behavior and more resistant to its treatment. A meta-analysis published in 2011 breaks the effect of light and heavy cannabis use into three categories. Acute effects observed within the six hours following consumption, residual effects observed within seven hours and 20 days of consumption, and persistent effect observed over three weeks after consumption. Authors found that attention and cognitive were impaired acutely in light users whereas heavy users showed normal for these parameters. Residual effect were mixed. Long term attention and cognition were observed to be normal. Working memory was incurred in their acute period but normalized in residue and long term periods. Decision making and risk taking were impaired in the residual and persistent time frame, but not conclusive for acute cannabis use. A systematic review from 2016 evaluated empirical research published in the decades spanning the years 2004 and 2015 on acute and chronic effects of cannabis and on persistence or recovery after abstinence. Verbal learning, memory, and attention were found to be most consistently impaired by acute and chronic exposure to cannabis. Psychomotor function was mostly affected during acute intoxication with some evidence for persistence both in chronic users and after cessation of use. It was found that impairment in verbal memory, attention, and some executive functions may persist after prolonged abstinence. Now let's give some attention to the relation between cannabis use and psychosis. Epidemiologic studies provide strong enough evidence to warrant a public health message that cannabis use can increase the risk of psychotic disorders. However, further studies are required to determine the magnitude of effect, the effect of different strains of cannabis on risk, and to identify high-risk groups particularly susceptible to the effect of cannabis on psychosis. A 2012 study tested whether the onset of cannabis use has an effect on the initiation of psychosis. The author examined the time relationship between onset of use and onset of psychosis, restricting the analysis to a cohort of individuals who only use cannabis and no other street drugs. In order to distinguish the effects of cannabis from possible effects of other illicit drugs. 57 participants who used cannabis prior to developing a psychosis were interviewed. Results showed that the age of onset of cannabis use was directly associated with the age of onset of psychosis and the age of first hospitalization. These results are consistent with the assumption that cannabis can cause or precipitate the onset of psychosis after a prolonged period of time. Several sources show that age of initiation to cannabis predicts the time to onset of mental illness. In a 2013 report, researchers investigated the existence of temporal association between age and initiation of cannabis use and age at onset of psychotic illness in about 1,000 participants from Australia. A temporal and direct relationship between age of initiation of cannabis use and age of onset of psychotic illness was detected with a premorbid exposure to cannabis of seven to eight years. The authors state that cannabis may exert a cumulative toxic effect on individuals on the pathway to developing psychosis. Lastly, let's ask ourselves, is cannabis addictive? A study from 2005 explored rates of cannabis dependence syndrome in individuals having used cannabis for less than two years and active users having initiated use more than two years before the assessment. The estimated rates of dependence were 3.9 and 9.9% respectively. Additional studies show a tendency of increase in the rates over the years, especially among young men, which maybe due to increased potency of cannabis. The association between increase frequency of use and cannabis potency that are characteristics of medical use raises significant concerns. In contrast to many recreational cannabis users, patients frequently consume high potency cannabis on a daily basis and often several times a day thus potentially putting them at high risk of developing a cannabis dependence syndrome.
