The results of the tests who evaluated the executive








The researchers at the end of this
study could affirm that their hypothesis it was correct. Exposure to   cannabis according with the age will
influence a lot the healthy development of the brain. Like it was mention at
the beginning the maturation of the brain still happen until early 20’s
different parts in different times. With the results of the tests who evaluated
the executive functioning of the participants helped to understand the
implications of consumption of this substance before and after age of 15. The
Authors didn’t find differences on executive functioning performance between
late-onset and non-users like they found in the early-onset. So, consumption of
cannabis before age 15 will impair the development of neurocognitive functioning
and consequently will lead to a bad performance of executive functioning.


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According with the tests results
of IQ, vocabulary and block design, didn’t exist differences between the early-onset,
late-onset and non-users. Doing comparisons, the early-onset had 3.64 more
errors than control group and they didn’t finished the all WCST. Also, on the
Stroop test they had a bad performance scoring (18.20) while the control group
only had (15.64). Finally, in FAB tests the late-onset scored (16.82), the
non-users scored (17.09) and the early-onset group had only (15.85).

The number of individual that participate
on the study was 148 of which 104 was chronic cannabis users and 44 were non-users
(control group), the group of 104 users of cannabis was divided by two those
who started before age 15 (55 individuals) and those who started after that age
(49 individuals).



Finally, to do the analysis
and comparisons of the neuropsychological measurements between the tree groups
early-onset, later-onset and non-users   the Authors used t- test (ANOVA).

Vocabulary and Block design, IQ (Wechsler Adult
Intelligence Scale-Revised (WAIS-R)- ability of verbally express vocabulary,
visuospatial and motor skills.

Frontal Assessment Battery (FAB) measure conceptualization,
mental flexibility, decision making environmental autonomy.

Wisconsin Card Sorting Test (Version 64) evaluate
capacity of planning, form abstract ideas, preservation, conceptualization.

Stroop Test (Victoria Version) evaluates the
speed and capacity of inhibit an automatic reading response.

All the individuals on the interview
day did an assessment psychosocial functioning, that measures medical history
an history of the substance use, (Urine analyses). They did the following
neuropsychological battery tests:

To this study They did a recruitment
of chronic cannabis users to participate on the treatment at the Substance Use Disorder
Program, Federal University of Sao Paulo. To be able to start treatment at UNIAD
all individuals had to do a interview and provide complete medical and
psychiatric history to determinate if they are eligible to participate or not. The
criteria of selection were people between 18 to 55 years, male and female, with
cannabis misuse or dependence, the person would be excluded if had   history of other DSM-IV disorders, current
use of psychoactive medications, history of head trauma with loss consciousness
for more than 5 min, intellectual disability or IQ below 80, vision or hearing
problems and abstinence was motivated but not mandatory. For this study they
also recruited a control group (non-users), the criteria it was almost the same
but to them all the way around they couldn’t use any psychoactive substance, not
use cannabis at all in the last 3 months or no been expose to more than 5
times. Although the participants sign a document accepting the terms and
conditions of the study and these interviews took a day-long.






The aim of this study is to do
an analysis to executive functioning of people who used cannabis before age 15
(early -onset group) compared with those who started after 15 (later-onset group)
and control (non-users). The hypothesis is that the early-onset will perform
worse on cognitive tests evaluating executive functioning comparative with later-onset
and non-users.

Consumption of cannabis/marijuana
during adolescence can influence negatively neuromaturation and cognitive
development. Even with weeks of abstinence, users of cannabis will show slower
psychomotor speed, poorer complex attention and memory skills and degraded
planning/ sequencing abilities comparing with non-uses.

According with the studies those
problems can occur because after birth the brain of the human been still
developing, certain areas of the brain like prefrontal cortex will develop in
different times and just rich maturation around early 20’s. So, the environment
will influence a lot the good or bad development of the brain.

These previous studies showed that
being expose to cannabis can cause neuropsychological issues, even if the
individual does some weeks of abstinence. They have another finding that this
substance can be more harmful to some individual than others, like people who
is expose to neurotoxic substances before age of 15 have big possibilities of
developing permanent neuropsychological deficits comparing with individual who
started after age of 15.

Adolescence is a really
vulnerable phase to brain development and substance abuse can impair the
neurocognition of the individual. Just some studies measured the differences in
cognitive performance from who started before age of 15 with those who started