Cannabis is oneof the drugs that has been used for years and nowadays it is the most commondrug used by teenagers. Adolescents who use cannabis very often have a chanceof affecting their brain functions. There are many studies that show the sideeffects of cannabis on individuals’ behaviour and their cognitive performance,mainly adolescents who consume neurotoxic substances before the age of 15 wherethe brain is still developing.
One of these studies is the experiment focusedby Fontes, et al. (2011). This analysis was based on 104 participants whostarted consuming cannabis in their early adolescence and those who startedconsuming it later (before and after the age of 15). The hypothesis of thisexperiment was that teenagers consuming cannabis before the age of 15 will not performwell on the cognitive tests given. The article byFontes, et al. (2011) focuses on the 104 participants who were cannabis usersand were following a treatment at the Drug and Alcohol Unit at the Universityof Sao Paolo. These 104 individuals were divided in three groups. The firstgroup were the early onset who started consuming chronic cannabis before theage of 15.
The second group were the late onset, individuals who started consumingcannabis after the age of 15. The third group were the non-users who had notused cannabis at all in the last 3 months and had not used it more than 5times. Neuropsychological tests were performed by the participants. Theseassessments were formed of a vocabulary and block design (WAIS-R) for IQestimation, a Stroop test (assess their cognitive speed and control), aWisconsin Card Sorting Test (help to measure individuals’ competence ability tosolve problems) and a Frontal Assessment Battery- FAB (a cognitive andbehavioural test to evaluate the frontal lobe functions). This studyverifies that the early onset group did not performed well in some taskscompering with the other groups. However, there was not a huge differencebetween early onset and late onset group. Overall, there were not any diversitybetween all three groups in the IQ test, WAIS-R test and block design.
Duringthe WCST test, compering with the control group, the early onset did not completeall the categories and they made repetitive errors. This clearly demonstrate thatindividuals consuming cannabis before the age of 15 are not incompetence onplanning, managing skills or even solving problems. In the FAB test the resultsshowed that the performance of the early onset was worse comparing with the lateonset and control group. A difference of 0.97 compering with the late onset and1.24 with the control group. The results showed that the early onset are notable to assess executive functions. While during the Stroop test there was a hugedifference in the score, where the control group scored lower (15.
64) than theearly onset (18.20). As can be seen, the results demonstrate thatchronic cannabis users before the age of 15 tend to have a side effect on thebrain development as the brain is still developing in that stage. In effect,the hypothesis of this study is right as the early onset group performed poorlyin most of the tasks.