The Fontes, et al. (2011) study investigated the impact of cannabis abuse on brain development prior to and subsequent to attaining the age of fifteen years. Studies found that puberty is a stage of significant exposure to neurocognitive effects that are associated with substance abuse. The authors point out few important studies that have tried to measure the differences in cognitive performance involving chronic addicts of cannabis who begun abusing cannabis before attaining the age of fifteen years with chronic addicts who started after reaching the age of fifteen. Brain imaging studies have demonstrated that the brain, prior to the reaching fifteen years of age, is under a complicated course of biological development. The motive of the study by Fontes, et al. (2011) was to probe the executive functioning of persons who began chronic abuse of cannabis before attaining the age of fifteen years, compared with those who started after attaining the age of fifteen years.
Fontes, et al. (2011) asserts that, while a number of studies have found neuropsychological deficits linked to chronic cannabis exposure, there are study outcomes investigating recurrent cognitive impairments linked to chronic cannabis that show contradictory points of view. The authors continue to assert that some studies demonstrate that even after practicing abstinence, chronic cannabis addicts may continue to experience considerable neuropsychological deficits. The authors explain that these conflicting findings may be based on the hypothesis that the neurotoxic impact of cannabis differ among populations. In this regard, when persons of less than fifteen years of age are exposed to substances that are potentially neurotoxic, they become more liable to develop recurrent neuropsychological deficits, in comparison to older persons.
Fontes, et al. (2011) asserts that adolescents are at risk of defective cognitive effects related to the abuse of cannabis. Puberty is a stage in which the brain seems to be defenceless to the neurotoxic impact of cannabis. The authors assert that results from diverse studies imply that chronic cannabis addicts process complicated information significantly slowly, while performance deteriorates in cognitive overload responsibilities as lifetime use increases.
In the study, Fontes, et al. (2011) held the hypothesis that the early-onset group (prior to 15 years of age) was likely to exhibit poor performance in cognitive tests that evaluate executive functioning, in comparison to the late-onset group, and the healthy controls. In this experiment Fontes, et al. (2011) investigated the effect on executive functioning on 104 chronic cannabis addicts. While focusing on executive functioning, the group was divided in two sets, where 49 individuals were chronic users in the early-onset category and 55 individuals, late-onset chronic users, as well as 44 healthy controls that carried out neuropsychological responsibilities. The control cluster concerned individuals who had not abused cannabis in the previous three months, and less than five instances across their lifetime. These chronic users of cannabis were initially under care at the Substance Use Disorder Program, Federal University of Sao Paulo. The inclusion criteria employed for chronic users of cannabis was males and females, between eighteen and fifty-five years of age, exhibiting cannabis abuse or addiction. The criteria for exclusion entailed present record of other disorders, excluding nicotine-related disorders as stipulated by CIDI; present usage of psychoactive drugs, record of head trauma with seizures for above five minutes, intellectual incapacity or approximate IQ less than 80, as well as irreparable hearing, vision or injury. Persons in the control group were eligible for the study on condition that they were between eighteen and fifty-five years of age, and did not abuse psychoactive substances, did not hold a record of head trauma, and never diagnosed with Axis I DSM-IV disorders in their lifetime. The study’s protocol was endorsed by the local institutional review board, while the respondents were under obligation to consent in writing, in line with the Federal University of Sao Paulo review board.