The study aims at knowing how low marijuana doses affect cognitive ability in postprimary students. The objective of the quantitative research was to analyze the results of neuropsychological and Neuro-SPECT tests comparing schoolchildren who smoke marijuana with those who do not, with emphasis on the effects on cognitive functions involved in learning. We wanted to assess the effects on the cerebral function of marijuana-only users. It was a comparative study based on the total sample of 565 school adolescents coming from four schools in the metropolitan area of Santiago, Chile. All were interviewed in order to select a sample that was stratified by sex, class and consumption of marijuana. The following two groups were made: 40 marijuana-only users and 40 nonusers. We took as a reference a study performed by the authors in 2007, in which the correlation between the consumption of marijuana and effects on cognitive functions involved in scholastic learning were established. The findings show statistically significant differences in the following areas: subgenual bilateral hypoperfusion, more marked on the left side (Brodmann area 25), frontal bilateral hypoperfusion (Brodmann’s areas 10 and 32), front cingulate gyrushypoperfusion (Brodmann area 24) and hypoperfusion of Brodmann area 36 that projects to the hippocampus. The results are highly matched with the neuropsychological tests given in the sense that, like with the 2007 study, significant differences are found between the two groups as far as the tests measuring cognitive functions are concerned. A qualitative research: we wanted to investigate the experience of time in high school students who regularly smoke marijuana, given that this substance has effects on the prefrontal lobe and on the hippocampus, brain areas related to the ability to plan tasks (executive function) and to memory. Moreover, adolescence is a delicate stage in regard to planning of the future. At the same time, the idea was to understand and make use of the concepts of temporariness and anticipation, which as a general rule will be handled only by philosophical theories. Our guiding principle is the ability to “anticipate oneself,” proposed by Sutter, a phenomenological psychiatrist. Data were analyzed from the autobiographies of the students through the hermeneutical phenomenological method developed by Lindseth, based on Ricoeur. Results allow answering the question of the study about the temporary experiencing of the young abusive marijuana consumer. The results showed poverty in the temporary dimensions referring to the past and the future, while in the report, it is more developed in the present moment. They appear detained in a more childish stage, in which the present predominates, and the future seemed not to be united with the past, which impresses as if it were “avoided.” What has been (past) does not link with what is wanted to be, so, elements of the past have no relation with future project.
Part of the book: Child and Adolescent Mental Health