The years of age. Fontes, et al. (2011)

The Fontes, et al. (2011) study investigated the impact of cannabis use on the development of the brain  prior to and subsequent to attaining
the age of fifteen years. The authors referred to several scholars who previously
investigated these relationships, and they indicate that most of these studies
suggest that puberty is a stage of major
exposure to neurocognitive effects
related to substance misuse. in
contrast, the authors point out that few important studies have attempted to measure the disparities in cognitive performance involving
chronic cannabis addicts who begun abusing cannabis prior to attaining fifteen years of
age, with chronic addicts who begun
after reaching fifteen years of age.
Longitudinal, as well as
cross-sectional structural brain imaging
research demonstrate that the brain, prior to the reaching fifteen years of age, is under a complicated path
of 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 reaching the age of fifteen, relative
to those who begun subsequent
to reaching fifteen years of age. Fontes,
et al. (2011) assert that, while a number of studies have recognized
neuropsychological deficits related to
chronic cannabis experience, there are study outcomes investigating
recurrent cognitive impairments associated to chronic cannabis
that confirm contradictory viewpoints.  The authors continue to assert that some studies
demonstrate that even subsequent to abstinence,
individuals who are chronic
cannabis addicts may continue
to encounter considerable
neuropsychological deficits.
The authors allege that these
conflicting outcomes may be
based on the theory that the neurotoxic effects of cannabis differ in populations. In this regard, when individuals below 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. The authors allege that results
from diverse studies imply that chronic cannabis addicts figure out complicated information significantly
slowly, while performance
deteriorates in cognitive overload duties
as cannabis use increases. It is in this background that Fontes, et al. (2011) investigated
the effect on executive functioning among 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 addicts and 44 cannabis-free controls
that carried out neuropsychological duties.
The control group involved individuals who not abused cannabis three months earlier or more than in five incidences across their lifetime. Comparisons relating to neuropsychological
measures were carried out by means of generalised
linear model analysis of
variance (ANOVA). In the study,
Fontes, et al. (2011) held the theory that the early-onset group was likely to exhibit poor outcomes in cognitive tests that
evaluate executive functioning,
in comparison to the late-onset group,
and the healthy controls. The inclusion criteria employed for chronic
users of cannabis was males and females, between eighteen and fifty-five years of age, exhibiting DSM-IV cannabis abuse or addiction as stipulated by the Composite International Diagnostic Interview (CIDI). The criterion
for exclusion entailed existing
record of other DSM-IV Axis I disorders, excluding nicotine-related
disorders as stipulated by CIDI;
present usage of psychoactive drugs,
record of head trauma with seizures for over five
minutes, intellectual incapacity or
approximate IQ less than eighty, 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. The study outcomes point out that the early onset
cohort are cognitively impaired in relation to controls, meaning that early use of cannabis is linked to negative
impact on the brain. These outcomes correspond to former studies that investigated cognitive effects linked to early
exposure to cannabis. The study did not establish disparities
in executive functioning outcomes between the late-onset group and the healthy group. In conclusion,
the study findings imply that
early-onset chronic users of cannabis but not display executive deficits, while the contrary is the case in the late-onset group. While the fundamental mechanisms may
not be entirely
understood, it is apparent that
exposure to cannabis at an early age might hold more significant detrimental
impact on neurocognitive functioning.