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An Evidence-Based Review of Acute and Long-Term Effects of Cannabis Use on Executive Cognitive Functions



Cannabis use has been shown to impair cognitive functions on a number of levels-from basic motor coordination to more complex executive function tasks, such as the ability to plan, organize, solve problems, make decisions, remember, and control emotions and behavior. These deficits differ in severity depending on the quantity, recency, age of onset and duration of marijuana use. Understanding how cannabis use impairs executive function is important. Individuals with cannabis-related impairment in executive functions have been found to have trouble learning and applying the skills required for successful recovery, putting them at increased risk for relapse to cannabis use. Here we review the research on the acute, residual, and long-term effects of cannabis use on executive functions, and discuss the implications for treatment.
An Evidence Based Review of Acute and Long-Term Effects of
Cannabis Use on Executive Cognitive Functions
Rebecca D. Crean, Ph.D.1, Natania A. Crane, B.A.1, and Barbara J. Mason, Ph.D.1,
1 Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute; La
Jolla, CA, 92037, USA
Cannabis use has been shown to impair cognitive functions on a number of levels—from basic
motor coordination to more complex executive function tasks, such as the ability to plan, organize,
solve problems, make decisions, remember, and control emotions and behavior. These deficits
differ in severity depending on the quantity, recency, age of onset and duration of marijuana use.
Understanding how cannabis use impairs executive function is important. Individuals with
cannabis-related impairment in executive functions have been found to have trouble learning and
applying the skills required for successful recovery, putting them at increased risk for relapse to
cannabis use. Here we review the research on the acute, residual, and long-term effects of cannabis
use on executive functions, and discuss the implications for treatment.
cannabis; marijuana; cognition; executive functions; treatment
Consumption of cannabis for medical purposes is legal with a prescription in 15 states, and
many states are in the process of decriminalizing non-medical marijuana use. More than
97.5 million Americans over the age of 12 have used illicit marijuana, and it is considered
by many to be a benign recreational drug. However, evidence exists of significant harm for
some individuals, with 1 in 10 users developing cannabis dependence (SAMHSA, 2007).
Furthermore, sixteen percent (~300,000) of all substance abuse treatment admissions in the
United States were for cannabis-related disorders; this is second only to alcohol-related
disorders (SAMHSA, 2006). It is estimated that more than 4 million Americans meet
Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV; APA, 1994) diagnostic
criteria for cannabis dependence (SAMHSA, 2007). This figure has doubled from 2001, and
will likely continue to grow. Thus, an understanding of the effects of cannabis on executive
functions is likely to be of widespread clinical relevance.
Delta 9-tetrahydrocannabinol (THC) is the primary psychoactive constituent of the cannabis
sativa plant and is believed to be primarily responsible for the cognitive effects and the
addictive potential of smoked cannabis. THC intoxication has been shown to impair
cognitive function on a number of levels—from basic motor coordination to more complex
Address correspondence to: Dr. Barbara J. Mason, Committee on the Neurobiology of Addictive Disorders, 10550 North Torrey Pines
Road, TPC-5; The Scripps Research Institute, La Jolla, CA 92037; USA; Phone: +1.858.784.7324; Fax: +1.858.784.7340;
The authors have no relevant financial interests to disclose.
NIH Public Access
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Published in final edited form as:
J Addict Med
. 2011 March 1; 5(1): 1–8. doi:10.1097/ADM.0b013e31820c23fa.
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tasks, such as the ability to plan, organize, solve problems, make decisions, remember, and
control emotions and behavior. The higher level cognitive functions, termed executive
functions (see Table 1), are critically important, particularly when dealing with novel
situations in which decisions must be made. This array of higher cognitive functions are
vital for overriding and inhibiting responses that otherwise would be automatic or require
little thought, such as continued substance abuse (Luria, 2002).
Some cannabis-related executive function deficits improve after cessation of cannabis use
(Pope et al., 2002), but growing evidence suggests that other deficits persist after cannabis is
discontinued (Bolla et al., 2005), and may hinder an individual’s ability to make the best use
of behavioral therapies and put him or her at greater risk for relapse to cannabis use
(Aharonovich et al., 2008; Blume and Marlatt, 2009). Adding to the complexity of this issue
is the fact that many factors can impact cannabis-related impairment and recovery of
executive functions, including age of onset of smoking cannabis, years of use, and amount
of regular use (Grant et al., 2003). This clinical conundrum is compounded by the fact that
treatment professionals may not be able to easily identify patients with cannabis-related
impairment in executive functions without the benefit of neuropsychological assessment
(Fals-Stewart, 1997).
Although there is convincing evidence that acute cannabis use generally affects cognitive
and motor functions, it is less clear as to whether those deficits are short term and transient
or if they are more enduring. Previously published reports (Pope et al., 2001; 2002) using
traditional neuropsychological assessment methods typically show a resolution of deficits by
28 days of abstinence. However, as neuroimaging technology has improved, more recent
reports show subtle, long-term effects of cannabis on cognition and brain functioning (Bolla
et al., 2005). In addition, newly published reports suggest that the deficits change as a
function of the quantity of cannabis consumed and duration of use (Solowij et al., 1995;
2002; Grant et al., 2003). Adolescents who started smoking between the ages of 14–22 years
old and stopped by age 22 had significantly more cognitive problems at age 27 than their
non-using peers (Brook et al., 2008). In addition, adult cannabis users who began smoking
before the age of 17, but not users who began smoking after the age of 17, had significant
impairments in measures of executive functioning, including abstract reasoning, verbal
fluency, and verbal learning and memory compared to non-using controls (Pope et al.,
Understanding how cannabis use impacts executive functions is important for clinicians.
Patients who routinely use cannabis may have deficits that make it difficult for them to
adhere to treatment, to follow medical advice, and to experience successful outcomes.
Literature Search Criteria
A literature search was conducted through Medline and PsychInfo with no publication date
restrictions. The search terms used were “marijuana”, “delta-9-tetra-hydrocannabinol,”
“THC,” and “cannabis” crossed with “neuro,” “cognitive,” “assessment,”
“neuropsychological,” “brain functioning,” “executive functions,” “impairment” or
“clinical.” Articles containing these search terms were included in this evidence-based
review if they reported results of cannabis-related studies conducted in an adult, human
population and utilized neuropsychological assessments to assess executive functions.
Review papers, commentaries, pre-clinical studies and those involving human children and
adolescents were excluded.
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after use)
Smoking cannabis produces levels of THC in blood plasma that can be detected almost
immediately and which reach peak concentrations within minutes (Grotenhermen, 2003).
THC is fat soluble and, therefore, easily stored and released into the bloodstream
(Grotenhermen, 2003). Because it is fat soluble, THC has a long half-life and can be
detected in urine anywhere from one day to more than a month after ingestion (Huestis et
al., 1996). The psychoactive effects of cannabis are experienced immediately after smoking,
with peak levels of intoxication occurring after approximately 30 minutes and lasting several
hours (Grotenhermen, 2003).
Researchers first began studying the acute effects of cannabis on neuropsychological
functioning in the 1970’s and consistently found disruptions in learning and memory
functions (Ferraro, 1980). The findings on executive functioning, however, have been less
clear (Pope et al., 1995). For the purposes of this review, literature reviewed for the acute
effects of cannabis on executive functions are studies in which assessment took place
between immediately upon smoking cannabis and up to six hours since last use. The
findings are detailed below.
Attention and Concentration
Attentional processing is the ability to use both divided and sustained attention when
targeting a stimulus and it is mediated by the frontal lobes (Grady, 1999). Several
investigators studied the acute effects of cannabis specifically on attentional processing.
Hart et al. (2001) studied the effects of placebo, light (1.8%), and heavy (3.9%) THC
cigarettes in chronic, daily cannabis users and found no significant differences in the
accuracy of response to attentional tasks. However, performance on a tracking task, which
requires sustained attention, was found to improve significantly after the high dose of THC,
relative to the other conditions. Similarly, Haney et al. (1999) found that after acute
intoxication, daily cannabis users significantly improved on a task of divided attention.
Morrison et al. (2009) tested light cannabis users 30 minutes after administration of either
placebo or moderate (2.5%) THC cigarettes and found significant impairment in attention
and concentration in the THC group compared with the placebo group. These discrepant
findings may be explained by the characteristics of the subjects studied; Haney et al. (1999)
and Hart et al. (2001) studied chronic, daily cannabis smokers, whereas the subjects used in
Morrison et al. (2009) were infrequent cannabis users. Hence, the disparate findings may be
a function of sample differences involving degree of cannabis exposure and the degree of
tolerance and other neuroadaptions resulting from long-term cannabis use.
Information processing is a fundamental aspect of attention and concentration and a basic
building block of higher order cognitive processing. (Dosher and Sperling, 1998). Kelleher
et al. (2004) evaluated information processing in heavy, chronic cannabis users compared
with non-cannabis using controls. Cannabis users completed a task when abstinent and then
attempted the same task 30 minutes after smoking their “regular” amount of cannabis. They
found that users in the abstinent state showed significantly slowed information processing
speed compared with controls; however, functioning normalized after smoking cannabis.
According to the authors, this finding shows that abstinence following chronic cannabis use
may result in a deficit in information processing, which normalizes after acute intoxication.
They surmised that cannabis users who experience slowing of information processing as a
result of abstinence following chronic cannabis use may be at risk to resume smoking in an
attempt to regain information processing abilities.
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Decision-Making and Risk-Taking
Decision-making and risk-taking hinge on one’s ability to anticipate and reflect on the
consequences of one’s decision; both are sensitive to frontal lobe disruption (Bechara et al.,
2000), and have been a recent area of interest in cannabis research. Lane et al. (2005) found
that subjects exposed to a high dose of THC (3.6%) demonstrated significantly greater risk-
taking than subjects receiving lower doses of THC. Conversely, similar studies by
Ramaekers et al. (2006) and McDonald et al. (2003) found no significant differences in risk-
taking between groups.
Vadhan et al. (2007) tested chronic, daily cannabis users after administering placebo, light
(1.8%), or heavy (3.9%) THC and found no differences in performance on decision-making
tasks. The researchers did find, however, that both THC groups were significantly slower in
decision-making than the placebo group. On another decision-making task Ramaekers et al.
(2006) found that, compared to the placebo group, subjects receiving THC were
significantly less likely to make correct decisions. Additionally, those in the THC groups
required longer planning times (latency to respond) than the placebo group. It appears then
that the acute effects of cannabis on decision making and risk taking are somewhat
discrepant and may indicate a dissociable difference in functions. Overall, there is evidence
that acute cannabis use has observable deficits in aspects of planning and decision making
particularly with regard to response speed, accuracy and latency.
Inhibition and Impulsivity
Drugs of abuse are often linked to an array of socially unacceptable, poorly controlled, and
maladaptive behaviors, collectively referred to as impulsivity. Few controlled studies have
investigated the effects of acute doses of cannabis on impulsive behavior. In one study of 37
adults with a history of light cannabis use, acute intoxication with a high dose of THC
resulted in significant impairment on a measure of impulsivity (McDonald et al., 2003).
Another study (Ramaekers et al., 2006) found similar impairment on a task of inhibition in
intoxicated, chronic cannabis users. Given this evidence, it appears that acute cannabis use
promotes more impulsive behavior and less inhibition of maladaptive responses.
Working Memory
Another measure of executive function is working memory. For more than 40 years,
researchers have shown that cannabis consumption impairs working memory, or the ability
to hold and manipulate information and remember it following a short delay (Tinklenberg et
al., 1970; Miller et al., 1977; Heishman et al., 1997). This finding has been replicated in
present day research. In a recent study of chronic cannabis users, Hart et al. (2001) found
that acute intoxication resulted in significant impairment in working memory, and those
subjects receiving a higher dose of THC (3.9%) took significantly longer to complete the
Verbal Fluency
Morrison et al. (2009) studied verbal fluency, or the ability to generate letters or words in a
set amount of time, in recreational cannabis users 30 minutes after administering placebo or
moderate (2.5mg) THC. Compared with controls, they found no impairing effects on verbal
fluency abilities.
Summary of Acute Effects of Cannabis on Executive Functions
Research assessing the effects of acutely administered doses of cannabis on executive
functioning has yielded mixed results (see Table 2). Evidence of the impairing effects of
cannabis intoxication on attention and concentration is stronger in less experienced cannabis
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users than those with established drug tolerance; attention and concentration in the latter
group is disrupted more by acute abstinence than acute cannabis administration, probably as
a function of neuroadaptation to chronic, heavy cannabis use. Comparable effects were
observed on tasks involving information processing, a function that is a basic building block
for attention and concentration. Acute cannabis use has generally been found to impair
aspects of planning and decision-making, e.g. in terms of response speed, accuracy and
latency. Some studies also found risk-taking increased with higher doses of cannabis. Acute,
impairing effects of cannabis on tasks assessing inhibition and impulsivity have also been
documented. Verbal fluency appears intact following acute cannabis administration, but
cannabis-related impairments in aspects of working memory are well-established.
to 20 days after last use)
Cannabis use may impact executive functions for several weeks. The literature reviewed for
the residual effects of cannabis use on executive functions covers the period of time from 7
hours to 20 days since last use.
Attention and Concentration
Pope et al. (2001; 2002) tested current, heavy cannabis users, former heavy cannabis users,
and control subjects on days 0, 1, 7 and 28 of abstinence. On all 4 occasions, no significant
differences were found on attentional abilities. This finding was replicated by Jager et al.
(2006). Contrary to those findings, however, Solowij et al. (1995; 2002) assessed long- and
short-term cannabis users who were abstinent for 24 hours and found that their attention was
significantly impaired and they showed longer reaction times to complete the tasks,
compared with controls. Solowij et al. (2002) also reported impaired information processing
abilities in cannabis users compared with controls. Another study (Hermann et al., 2007) of
recreational cannabis users with an unknown duration of abstinence reported poorer
performance on attentional tasks, compared with controls.
Wadsworth et al. (2006) examined attentional capacities in “real world” situations; that is,
right before work and immediately after work, at both the beginning and end of the work
week. They found that, compared with controls, cannabis subjects had significantly impaired
attention both at the beginning of the work week and at the end, which was significantly
correlated with duration of cannabis use. This finding has implications for everyday
activities, suggesting that even with abstinence, some attentional deficits remain.
Decision-Making and Risk-Taking
In the single study assessing this domain, Whitlow et al. (2004) evaluated the performance
of chronic, heavy cannabis users with at least 12 hours of abstinence on a task that simulates
decision-making and risk-taking. Compared with controls, the cannabis users had
significantly impaired decision-making capacities and greater risk-taking tendencies. More
research is needed to augment the finding of residual cannabis effects on decision-making
and risk-taking.
Inhibition and Impulsivity
One of the first groups (Pope et al., 1996) to study inhibition and cognitive flexibility in
cannabis users examined heavy and light users after a minimum of 19 hours of abstinence.
Heavy cannabis users demonstrated significantly more errors of inhibition and perseveration
compared with light users. Solowij et al. (2002) replicated these findings in cannabis users
after at least 12 hours of abstinence. The severity of these deficits was correlated with years
of use. Several other researchers have found a similar pattern of impairment (Aharonovich et
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al., 2008; Cunha et al, 2010). In contrast, a number of researchers found no residual effects
of cannabis use on inhibition or impulsivity (Whitlow et al., 2004; Gruber et al., 2005;
Hermann et al., 2007); however, these studies had small sample sizes (e.g. N=10) and the
length of abstinence was unspecified or was highly variable, ranging from 12 hours to 18
years. Thus, although clear indication exists of impairment after acute cannabis intoxication,
the residual effects appear less consistent. One possible explanation may be the samples
sizes used in these studies lacked statistical power to detect differences. Studies that found
significant differences had much larger sample sizes than those detecting no differences.
Working Memory
Pope et al. (1996) found no differences in working memory abilities between recently
abstinent (19 hours) heavy and light cannabis users compared with control subjects. In
addition, no significant differences were found in working memory abilities of recently
abstinent cannabis users across multiple studies (e.g., Kanayama et al., 2004; Jager et al.,
2006; Solowij et al., 2002; Whitlow et al., 2004; Fisk et al., 2008).
Verbal Fluency
Pope et al. (1996) also studied verbal fluency in cannabis users and, while they did not have
a control group for comparison, they found no differences between heavy users and light
users after a minimum of 19 hours of abstinence. More recently Fisk et al. (2008) replicated
this finding in light users relative to controls. In contrast, McHale and Hunt (2008) analyzed
verbal fluency in regular cannabis users (past 6 months), recent cannabis users (past 7 days),
and controls. Subjects were tested 24 hours after their last use and significant differences in
verbal fluency were found between the cannabis and control groups. It is unclear why these
findings are discrepant; however, one possible explanation is the difference in samples used.
Pope et al. (1996) did not use a control group and Fisk et al. (2008) used very light users,
while McHale and Hunt (2008) used more regular, frequent users.
Summary of the Residual Effects of Cannabis on Executive Functions
Investigations on the residual effects of cannabis on executive functioning show that
recently abstinent cannabis users (7 hours to 20 days) may experience impairment in certain
aspects of executive functioning. Attention, concentration, inhibition and impulsivity may or
may not continue to be impaired during the interval associated with the elimination of THC
and its metabolites from the brain. Decision-making and risk-taking capabilities have not
been thoroughly studied during this period, but a single study by Whitlow et al. (2004)
suggests that these abilities are impaired. In contrast to the acute effects of cannabis in
working memory, deficits as a function of residual cannabis effects have not been found.
Findings for verbal fluency are somewhat mixed, but may be due in part to sample
differences in degree of cannabis exposure. Studies showing the greatest deficits in
executive functioning used subjects who had been smoking heavy amounts of cannabis for
long periods of time. It is likely that residual impairments are linked to the duration and
quantity of cannabis use.
weeks or longer since last use)
The long-term effects of cannabis use have received the greatest research attention in recent
years. Nevertheless, this area of the literature has been fraught with inconsistencies in
findings and is complicated by discrepant definitions of what constitutes “long-term
effects.” For the purpose of this review, long-term effects refers to 21+ days since last using
cannabis, which ensures that both the acute and residual effects of cannabis in the brain have
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been eliminated. Only a handful of researchers have examined these long-term effects of
cannabis use on executive functions, as reviewed below.
Attention and Concentration
In five of seven studies, no attention or concentration impairments were found in subjects
who had remained abstinent from 28 days to one year (Lyons et al., 2004; Pope et al., 2001;
2002; 2003; Verdejo-Garcia et al., 2005). Conversely, of the two remaining studies, Solowij
(1995) examined cannabis users abstinent from 6 weeks to 2 years and found significant
impairment in selective attention and concentration. Likewise, Bolla and colleagues (2002)
found long-term deficits in attention and concentration in a sample of heavy, chronic
cannabis users, abstinent for approximately 28 days. It is possible that these disparate
findings are attributable to impairment in basic information processing skills rather than
higher level attentional abilities. Information processing has not been examined in long-term
cannabis abstinence.
Decision-Making and Risk-Taking
Another cognitive construct recently examined in abstinent cannabis users is decision-
making and risk-taking. One study compared cannabis users, cocaine users, and control
subjects who were abstinent 25 days and found a trend towards significant impairment in
decision-making and risk-taking in the cannabis group compared with non-cannbis using
controls and no differences in performance when compared with the cocaine group
(Verdejo-Garcia et al., 2006).
Inhibition and Impulsivity
The majority of research assessing the long-term effects of cannabis on inhibition and
impulsivity have used two different tests: the Stroop Test or the Wisconsin Card Sort Test
(WCST). Studies using the Stroop test have consistently found no significant differences
between cannabis and control groups (Lyons et al., 2004; Pope et al., 2001; 2002; 2003;
Verdejo-Garcia et al., 2005). In contrast, studies using the WCST have all found significant
differences (Bolla et al., 2002, Pope et al., 2001; 2002; 2003), with the exception of Lyons et
al. (2004). That study examined male monozygotic twins who used varying amounts of
cannabis (>1 time/wk for a minimum of 1 year versus < 5 times in their life time) and found
no differences between the siblings. The Stroop test requires active selection and, as a result,
may require inhibition of some aspects of attention to produce the appropriate response
(Kosmidis et al., 2006) whereas the WCST requires additional functions such as
conceptualizing, developing, and testing hypotheses, as well as inhibition (Huguelet et al.,
2000). Both tests require the ability to perform set shifting and maintenance. It is possible
that the discrepant findings in the cannabis literature may represent intact set shifting and
maintenance but impairment in concept formation, planning and sequencing.
Working Memory
The only known study to analyze the long-term effects of cannabis on working memory is
Vardejo-Garcia and colleagues (2005). This study did not find any significant differences
between abstinent cannabis users and polysubstance abusers. Perhaps studies using a control
group may yield more definitive findings in this area.
Verbal Fluency
Pope et al., (2001; 2002; 2003) examined verbal fluency after 28 days of abstinence.
Performance differences between groups reported in the earlier studies were nonsignificant;
however, the most recent study showed significant differences between groups on verbal
fluency. This later study divided the cannabis groups based on age of onset (early and late)
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and compared their performance with a control group. Early onset cannabis users (who
began smoking before age 17) demonstrated significant impairments in verbal fluency
compared with controls. These findings suggest that age of onset, and possibly years of use,
mediates the impact of long-term effects of cannabis on verbal fluency.
Summary of the Long-Term Effects of Cannabis on Executive Functions
Cannabis appears to continue to exert impairing effects in executive functions even after 3
weeks of abstinence and beyond. While basic attentional and working memory abilities are
largely restored, the most enduring and detectable deficits are seen in decision-making,
concept formation and planning. Verbal fluency impairments are somewhat mixed at this
stage. Similar to the residual effects of cannabis use, those studies with subjects having
chronic, heavy cannabis use show the most enduring deficits.
Few fully controlled treatment studies for cannabis dependence have been published and
those focus primarily on motivation enhancement therapy (MET), cognitive-behavioral
therapy (CBT), or a combination of the two (Nordstrom and Levin, 2007). High relapse rates
were found, which were comparable to those for alcohol, tobacco, and other drugs of abuse,
but were better than those for a delayed treatment control group (e.g., Stephens et al., 2000).
A review of these studies by Nordstrom and Levin (2007) concluded that psychotherapy has
been shown to reduce cannabis use, but that no form of psychotherapy performs
significantly better than another in terms of reduced use and longer psychotherapy studies do
not provide any added benefit over shorter studies (i.e., 3 months versus up to 15 months).
When a patient presents for treatment with a cannabis use problem, the treatment provider
may wish to consider obtaining a neuropsychological assessment of executive functions, as
deficits may have important implications for treatment outcome. Neuropsychological studies
in adult cannabis users show deficits in multiple areas of executive functioning (e.g.,
attention, decision-making, inhibition). As previously discussed, deficits in executive
functioning may be long lasting in some individuals and may impact everyday functioning.
In addition, it is important to determine the age of onset of cannabis use, as cannabis use
typically begins in adolescence, while the brain is still maturing. A number of studies
examining executive function across adolescence and early adulthood found abilities such as
planning, inhibition, and decision-making continue to develop into early adulthood (Romine
and Reynolds, 2005; Rubia et al., 2006; Eshel et al., 2007). Cannabis use throughout
adolescence and young adulthood may impair achievement of such developmental
milestones in executive functioning such that deficits persist after establishing abstinence.
Behavioral therapies for the treatment of cannabis dependence rely on intact cognitive
functions, yet the implications of cannabis-related cognitive impairments on treatment
outcome have received little attention. On a related note, studies in alcohol-dependent
subjects suggest that executive function impairments have a negative impact on treatment
success (Gottschalk et al., 2001; Bates et al., 2006). Cognitive impairment has also been
generally associated with poorer drug abuse treatment outcomes (Crawford, 1978; O’Leary
et al., 1979; Abbott and Gregson, 1981; see also Aharonovich et al., 2008) and these deficits
have been found to impede acquisition of new coping behaviors (McCrady and Smith,
1986), learning and retention of new material (Alterman and Hall, 1989), and to increase the
likelihood of treatment dropout (Teichner et al., 2002).
The long-term executive functioning deficits associated with cannabis dependence and the
associated risks for poor treatment outcome suggests that cognitively impaired cannabis
users may not respond optimally to standard cognitively oriented treatment, such as CBT
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(Aharonovich et al., 2008). In fact, concern has been expressed that cognitive therapy
approaches may not be effective with patients who have cognitive deficits (Verdejo-Garcia
et al., 2004). A first-line approach may be to expose these patients to cognitive rehabilitative
strategies such as encouraging them to check and double-check their work, to give
themselves ample time to complete a task, to build in delays before responding so they can
weigh the costs and benefits of their actions instead of reflexively responding to situations
and to write things down and use repetition and cues to remember important tasks and
information. More research is needed in this area, both to better understand the complex
effects of executive functioning and treatment outcome and to identify the methods for
optimizing treatment outcome in patients with cannabis-related impairments in executive
function (Blume and Marlatt, 2009).
Prevalence rates for cannabis use have increased in recent years (SAMHSA 2007), and as
such, chronic, heavy cannabis use is a growing health concern. Research on the effects of
cannabis on cognition has generally lagged behind studies on the cognitive effects of
alcohol, cocaine, methamphetamine and heroin, and only recently appears to be gaining
momentum. Even less attention has been given to the effects of cannabis on executive
functions. There are some important methodological differences to take into consideration
when interpreting the sometimes disparate results of studies of cannabis effects on executive
functions, such as the recency, amount, duration and age of onset of cannabis use.
The trajectory of effects of cannabis on executive functions follows an interesting pattern of
recovery of some functions and persisting deficits in others (see Table 2). The acute effects
of cannabis use are evident in attentional and information processing abilities with recovery
of these functions likely after a month or more of abstinence. Decision-making and risk-
taking problems aren’t necessarily evident immediately after smoking; however, if cannabis
use is heavy and chronic, impairments may emerge that do not remit with abstinence,
particularly if heavy use was initiated in adolescence such that maturation of executive
functions was not achieved. Acute cannabis use impairs inhibition and promotes impulsivity,
and over a period of abstinence, these deficits are most evident in tasks that require concept
formation, planning and sequencing abilities. Working memory is significantly impaired
following acute exposure to cannabis; however, these deficits resolve with sustained
abstinence. Evidence is less clear in regards to verbal fluency abilities; however, research
suggests that chronic, heavy use may impact verbal fluency abilities even after long-term
abstinence. The long-term effects of cannabis on executive function is most clearly
demonstrated when studies use chronic, heavy cannabis users, as opposed to light,
occasional users. Yet even occasional cannabis use can acutely impair attention,
concentration, decision-making, inhibition, impulsivity and working memory.
An understanding of the effects of cannabis use on executive functions has considerable
practical utility in the clinical setting. The consolidation of findings in this review can
provide clinicians with an overview of the documented effects of cannabis use on executive
functions as they relate to age of onset, duration, quantity and recency of use with
consequent treatment implications. With this information, clinicians can inform their
patients who are regular, heavy, cannabis users of the cognitive liabilities associated with
continued use, and better understand the impairments their cannabis-abusing patients
experience in comprehending, processing, and following-through on important health and
treatment advice relevant to sustaining their recovery.
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Definitions of Key Aspects of Executive Functioning
Aspect of Executive
Functioning Definition
Attention Process of selectively attending to one aspect of the environment while ignoring other things, includes divided
and sustained attention to target stimuli
Concentration Intense mental application
Decision Making Process of selecting a course of action among several alternatives
Impulsivity Initiation of behavior without adequate forethought as to the consequences of actions
Inhibition Imposing restraint upon behavior or another mental process; resistance to prepotent responding
Reaction Time Lapse of time between the presentation of a stimulus and a response
Risk Taking Engaging in behaviors that have the potential to be harmful or dangerous
Verbal Fluency Generating multiple, verbal responses associated with a specified conceptual category
Working Memory Ability to hold and manipulate information and remember it following a short delay
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A Summary of Research Findings on the Effects of Cannabis on Executive Functions
Executive Function Measured Acute Effects Residual Effects Long-Term Effects
Attention/Concentration Impaired (light users)
Normal (heavy users) Mixed findings Largely normal
Decision Making & Risk Taking Mixed findings Impaired Impaired
Inhibition/Impulsivity Impaired Mixed findings Mixed findings
Working Memory Impaired Normal Normal
Verbal Fluency Normal Mixed findings Mixed findings
Note: Acute Effects denotes 0–6 hours after last cannabis use; Residual Effects denotes 7 hours to 20 days after last cannabis use; Long-Term
Effects denotes 3 weeks or longer after last cannabis use.
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... 12,45,46,53,60,62 Although some systematic reviews demonstrate that cannabis is associated with reductions in chronic pain 45,62 and improvements in sleep and physical functioning, 60 others show minimal therapeutic benefit for chronic pain. 12,46,53 Many adults can use cannabis with little harm, although for others its use also can have negative consequences, including impaired cognitive functioning, 9,42 motor vehicle crashes, 50 suicidal ideation, 24 and lower quality of life. 20 In addition, 20% to 33% of adults who use cannabis develop cannabis use disorder (CUD), 34 characterized by a problematic and persistent pattern of use that contributes to impaired social and occupational functioning. ...
In the United States, cannabis is increasingly used to manage chronic pain. Veterans Health Administration (VHA) patients are disproportionately affected by pain and may use cannabis for symptom management. Because cannabis use increases the risk of cannabis use disorders (CUDs), we examined time trends in CUD among VHA patients with and without chronic pain, and whether these trends differed by age. From VHA electronic health records from 2005 to 2019 (∼4.3-5.6 million patients yearly), we extracted diagnoses of CUD and chronic pain conditions (International Classification of Diseases [ICD]-9-CM, 2005-2014; ICD-10-CM, 2016-2019). Differential trends in CUD prevalence overall and age-stratified (<35, 35-64, or ≥65) were assessed by any chronic pain and number of pain conditions (0, 1, or ≥2). From 2005 to 2014, the prevalence of CUD among patients with any chronic pain increased significantly more (1.11%-2.56%) than those without pain (0.70%-1.26%). Cannabis use disorder prevalence increased significantly more among patients with chronic pain across all age groups and was highest among those with ≥2 pain conditions. From 2016 to 2019, CUD prevalence among patients age ≥65 with chronic pain increased significantly more (0.63%-1.01%) than those without chronic pain (0.28%-0.47%) and was highest among those with ≥2 pain conditions. Over time, CUD prevalence has increased more among VHA patients with chronic pain than other VHA patients, with the highest increase among those age ≥65. Clinicians should monitor symptoms of CUD among VHA patients and others with chronic pain who use cannabis, and consider noncannabis therapies, particularly because the effectiveness of cannabis for chronic pain management remains inconclusive.
... Indian hemp spoils numerous mechanisms of cognitive function, with the utmost vigorous effects on short-term discontinuous, working memory, response speed, planning, decisionmaking, and precision and expectancy (139)(140)(141)(142)(143)(144)(145)(146). In vivo and in vitro studies have revealed that it can disturb the hypothalamus-pituitary-gonadal axis, sperm function and spermatogenesis (147). ...
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Formulations having multiple crude drugs have been globally used according to literature records especially in Greek, ancient Egyptian, Chinese and Indian medical systems for miscellaneous therapeutic purposes. According to the World Health Organization (WHO), more than 80% of the world's populace use herbal and traditional medications. Crude drugs used in Siddha, Ayurvedic, and Unani system of medicines, belong to any of the five sources of crude drugs i.e., animals, plants, marine, metals and minerals and microorganism. As crude drugs especially herbs have plenty of phytochemicals so use of bioactive compounds solely is not sufficient to attain desired therapeutic effects. Combinations of numerous crude drugs in a specific proportion Journal of Xi'an Shiyou University, Natural Science Edition ISSN: 1673-064X VOLUME 19 ISSUE 05 MAY 2023 223-243 sometimes exhibit better therapeutic effectiveness with minimal toxicity. This review chiefly focuses on therapeutic importance with clinical implication of Habb-e-Nareena. The Habb-e-Nareena is a polyherbal formulation that was mentioned by Hakeem Muhammad Shareef Dunyapuri and Hakeem Muhammad Yaseen Dunyapuri in their books to treat the women suffering from Gonorrhea, Leukoria, menstrual disturbances, recurrent miscarriage, infertility and premature birth. The regional practices affirm that if the formulation is used after the completion of menstual cycle immediately, for almost 7 days then the women would certainly conceive within about one month or otherwise in next three months. Furthermore, the fetus must be a baby boy with XY gene combination. It is consisted of 6 crude drugs named as Mazu (whole), Bhang, Musk, Mazu (aqueous extract), Kushta faulad and Feathers of peacock.
... Expert consensus shows that cannabis use is associated with at least a modest increase in crash risk (International Council on Alcohol, Drugs, and Traffic Safety, 2022), and recent meta-analytic research has further revealed that drivers who test positive for THC or associated metabolites are approximately 30%-40% more likely to be involved in a collision, relative to drivers who test negative for cannabis (Rogeberg et al., 2016). Acute cannabis consumption has been linked to slowed reaction time (Hunault et al., 2009;Liguori et al., 1998), reduced working memory capacities (Curran et al., 2002;Lamers et al., 2006;Ploner et al., 2002;Ramaekers et al., 2021;Solowij et al., 2002), alertness and Effect of CannEpil ® on simulated driving performance and co-monitoring of ocular activity: A randomised controlled trial sustained attention abilities (Crean et al., 2011;Wadsworth et al., 2006), translating to a higher overall collision risk compared to unimpaired drivers (Sagberg et al., 2015;Tement et al., 2020). Research utilising on-road and simulated driving tasks following cannabis use has shown varying degrees of impairment on more direct measures of driving ability, including weaving of the vehicle (Hartman et al., 2015;Ramaekers et al., 2000), maintenance of speed (Tement et al., 2020) and variability in steering (Alvarez et al., 2021;Downey et al., 2013;Ronen et al., 2008). ...
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Background: Medicinal cannabis products containing Δ9-tetrahydrocannabinol (THC) are increasingly accessible. Yet, policy guidelines regarding fitness to drive are lacking, and cannabinoid-specific indexations of impairment are underdeveloped. Aims: To determine the impact of a standardised 1 mL sublingual dose of CannEpil®, a medicinal cannabis oil containing 100 mg cannabidiol (CBD) and 5 mg THC on simulated driving performance, relative to placebo and whether variations in vehicle control can be indexed by ocular activity. Methods: A double-blind, within-subjects, randomised, placebo-controlled, crossover trial assessed 31 healthy fully licensed drivers (15 male, 16 female) aged between 21 and 58 years (M = 38.0, SD = 10.78). Standard deviation of lateral position (SDLP), standard deviation of speed (SDS) and steering variability were assessed over time and as a function of treatment during a 40 min simulated drive, with oculomotor parameters assessed simultaneously. Oral fluid and plasma were collected at 30 min and 2.5 h. Results: CannEpil did not significantly alter SDLP across the full drive, although increased SDLP was observed between 20 and 30 min (p < 0.05). CannEpil increased SDS across the full drive (p < 0.05), with variance greatest at 20-30 min (p < 0.001). CannEpil increased fixation duration (p < 0.05), blink rate (trend p = 0.051) and decreased blink duration (p < 0.001) during driving. No significant correlations were observed between biological matrices and performance outcomes. Conclusions: CannEpil impairs select aspects of vehicle control (speed and weaving) over time. Alterations to ocular behaviour suggest that eye tracking may assist in determining cannabis-related driver impairment or intoxication. Australian and New Zealand Clinician Trials Registry,
... for synthesis, breakdown, and transportation of these ligands [5,6]. Cannabis use induces a host of physiological and cognitive changes in humans, both in acute exposure as well as after chronic use, resulting in altered physiology, executive function, nociception, and appetite, among others [7][8][9][10]. These results have also been observed in preclinical rodent models [11][12][13]. ...
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Background: Delta-9-tetrahydrocannabinol (THC) is the main psychoactive component of cannabis. Historically, rodent studies examining the effects of THC have used intraperitoneal injection as the route of administration, heavily focusing on male subjects. However, human cannabis use is often through inhalation rather than injection. Objective: We sought to characterize the pharmacokinetic and phenotypic profile of acutely inhaled THC in female rats, compared to intraperitoneal injection, to identify any differences in exposure of THC between routes of administration. Methods: Adult female rats were administered THC via inhalation or intraperitoneal injection. Serum samples from multiple time points were analyzed for THC and metabolites 11-hydroxy-delta-9-tetrahydrocannabinol and 11-nor-9-carboxy-delta-9-tetrahydrocannabinol using ultra-performance liquid chromatography-tandem mass spectrometry. Rats were similarly treated for locomotor activity analysis. Results: Rats treated with 2 mg/kg THC intraperitoneally reached a maximum serum THC concentration of 107.7 ± 21.9 ng/mL. Multiple THC inhalation doses were also examined (0.25 mL of 40 or 160 mg/mL THC), achieving maximum concentrations of 43.3 ± 7.2 and 71.6 ± 22.5 ng/mL THC in serum, respectively. Significantly reduced vertical locomotor activity was observed in the lower inhaled dose of THC and the intraperitoneal injected THC dose compared to vehicle treatment. Conclusion: This study established a simple rodent model of inhaled THC, demonstrating the pharmacokinetic and locomotor profile of acute THC inhalation, compared to an i.p. injected THC dose in female subjects. These results will help support future inhalation THC rat research which is especially important when researching behavior and neurochemical effects of inhaled THC as a model of human cannabis use.
... Tetrahydrocannabinol (THC) binds to cannabinoid receptors in the brain, causing feelings of well-being, euphoria, and anxiolysis, but also altering systems involved in memory, concentration, and time perception [72]. Indeed, chronic cannabis consumption alters executive functions in a similar way that ADHD does [73], with impaired sustained attention and working memory [74], and possibly alters brain circuitry accountable for response inhibition [75], impulsivity [76], cognitive control [77], reward processing [78], circadian rhythms [79], and motivation [80]. ...
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Adults with attention deficit/hyperactivity disorder (ADHD) often present psychiatric comorbidities and, in particular, substance use disorder (SUD). ADHD-SUD comorbidity is characterized by greater severity of both disorders, earlier age of onset, higher likelihood of polydrug-abuse and suicidal behaviors, more hospitalizations, and lower treatment adherence. At the present stage, research focused on the pharmacological management of ADHD with comorbid SUD in both adolescents and adults is still lacking. Furthermore, while the short-term effects of stimulants are well studied, less is known about the chronic effects of these drugs on dopamine signaling. Current available evidence is consistent in reporting that high doses of stimulant medications in ADHD-SUD subjects have a mild to moderate efficacy on ADHD symptoms. Some data suggest that pharmacological treatment with stimulants may be beneficial for both ADHD symptoms and comorbid cocaine or amphetamine use. However, in the long run, stimulant medications may have a potential risk for misuse. For the absence of potential misuse, atomoxetine is often recommended for ADHD with comorbid cocaine or amphetamine use disorder. However, its efficacy in reducing addictive behavior is not demonstrated. In subjects with other subtypes of SUD, both atomoxetine and stimulant drugs seem to have scarce impact on addictive behavior, despite the improvement in ADHD symptomatology. In this population, ADHD treatment should be combined with SUD-specific strategies.
Introduction: Policies to legalize possession and use of marijuana have been increasingly supported across the United States. Although there are restrictions on use in minors, many substance abuse scientists anticipate that these policy changes may alter use patterns among adolescents due to its wider availability and a softening of beliefs about its potentially harmful consequences. Despite the possibility that these policies may increase the prevalence of use among adolescents, the effects of marijuana on neurodevelopment remain unclear, clouding arguments in favor of or opposition to these policies. Methods: The present prospective, longitudinal study was designed to isolate the neurodevelopmental consequences of marijuana use from its precursors during adolescence-a period of heightened vulnerability for both substance use and disrupted development due to environmental insults. Early adolescents who were substance-naïve at baseline (N = 529, aged 10-12) were recruited and tracked into adolescence when a subgroup initiated marijuana use during one of three subsequent waves of data collection, approximately 18 months apart. Results: Results suggest that marijuana use may be specifically related to a decline in verbal learning ability in the short term and in emotion recognition, attention, and inhibition in the longer-term. Discussion: These preliminary findings suggest that marijuana use has potential to adversely impact vulnerable neurodevelopmental processes during adolescence. Intensive additional investigation is recommended given that state-level policies regulating marijuana use and possession are rapidly shifting in the absence of good scientific information.
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This review paper highlights about Medical Cannabis sativa (Marijuana or drug type) containing psychoactive molecule, Δ9-Tetrahydrocannabinol (Δ9-THC) as a part of educational awareness programme in India. Cannabis sativa and Cannabis indica were originally a native of India growing as a wild notorious noxious weed in the Indian Himalayan region. Marijuana (Charas, Ganja and Bhang in India) is a mind-altering (psychoactive) drug, produced by the Cannabis sativa plant. Marijuana (Charas, Ganja or Bhang drink in India) is an illicit drug containing very high levels (25-35%
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Objective Adverse childhood experiences (ACEs) are common and robustly predict drug misuse. Dispositional mindfulness inversely associates with both childhood adversity and drug use severity. However, mindfulness is a multi-faceted construct, and emerging findings suggest that facets may differentially link to favorable outcomes. The present study tested the hypothesis that mindfulness facets would differentially mediate the relationship between ACEs and cannabis misuse. Method A college student sample (n = 354) completed the Adverse Childhood Experiences Questionnaire (ACE), Five Facet Mindfulness Questionnaire (FFMQ), and Cannabis Use Disorders Identification Test-Revised (CUDIT-R). Individual mediation models tested whether FFMQ total score and facets (Awareness, Nonjudge, Observe) differentially mediated the relationship between ACEs and CUDIT-R scores. Results Significant associations were observed between the number of ACE exposures, CUDIT-R severity, and the three FFMQ facets. The FFMQ Awareness (unstandardized indirect effect (IE) = 0.12, SE = 0.05, 95% CI [0.03, 0.22]), Nonjudge (IE = 0.24, SE = 0.07, 95% CI [0.11, 0.39]), and Observe (IE = 0.11, SE = 0.05, 95% CI [0.03, 0.22]) facets each partially mediated the relationship between ACE exposures and CUDIT-R severity in their individual models and accounted for 20%, 41%, and 19% of the variance in this relationship, respectively. Conclusions Findings highlight the differential importance of mindfulness facets and the need to consider the unique contributions of these facets in understanding the relationship on ACE-related consequences and drug misuse. Preregistration This study is not pre-registered.
Background - Data available in the literature indicate that cannabis consumption has greatly increased in the USA and in some European countries over the last years, parallel to an increased accidental exposure of children. Similar data from Italy are lacking. Objective - The aim of the study was to carry out an epidemiological investigation on acute cannabinoids intoxication in patients attending a city paediatric Emergency Room. Materials and Methods - Clinical records of all patients who came to the Emergency Room (Naples, Italy) from April 2016 to November 2017 were retrospectively reviewed and then the diagnosis of cannabinoid intoxication were selected and evaluated. Results - 111,989 visits were registered, and 436 cases (0.6%) were acute intoxications. Mean age was 3 ± 2.5 years. Ten of these (1.15%) were cannabinoid intoxication occurred for accidental ingestion in 7 subjects (mean age 2.15 ± 2.17 years) and for intentional inhalation in 3 (mean age 11.3 ± 1.5); p ≤ 0.0001. Diagnosis was always confirmed by the toxicological screening performed on a urine sample. Six of seven patients with accidental ingestion had a reduced state of consciousness, 3 of these had a severe clinical presentation. Two cases of 3 by intentional inhalation had mild symptoms, only one moderate showing visual hallucinations. Conjunctival hyperaemia was the most frequent associated symptom. Six of the 10 patients needed to receive supportive drug treatment, mainly saline infusion and/or oxygen therapy. The length of hospital stay was 12 hours for the cases of intentional intoxication and varied from 12 hours to 12 days (mean 88.6 hours, SD 103.6) for inadvertent intoxications (p: 0.25) with 1 patient admitted to the paediatric Intensive Care Unit. Conclusions - Cannabinoid intoxication should be always suspected when clinical presentation is not specific and/or is equivocal and when psychiatric manifestations are present. Moreover, the rapid urine toxicology test should become part of the routine screening in the Emergency Room.
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The relationships between executive processes, associative learning and different aspects of real world memory functioning were explored in a sample of cannabis users and nonusers. Measures of executive component processes, associative learning, everyday memory, prospective memory, and cognitive failures were administered. Relative to nonusers, cannabis users were found to be impaired in several aspects of real world memory functioning. No other group differences were apparent. The absence of cannabis related deficits in those executive component processes and aspects of learning that are believed to support real world memory processes is surprising given that cannabis related deficits were obtained in real world memory. The present results are discussed within the context of neuroimaging evidence which suggests that cannabis users may exhibit different patterns of neural activation when performing executive tasks while not always exhibiting deficits on these tasks.
Context Cognitive impairments are associated with long-term cannabis use, but the parameters of use that contribute to impairments and the nature and endurance of cognitive dysfunction remain uncertain.Objective To examine the effects of duration of cannabis use on specific areas of cognitive functioning among users seeking treatment for cannabis dependence.Design, Setting, and Participants Multisite retrospective cross-sectional neuropsychological study conducted in the United States (Seattle, Wash; Farmington, Conn; and Miami, Fla) between 1997 and 2000 among 102 near-daily cannabis users (51 long-term users: mean, 23.9 years of use; 51 shorter-term users: mean, 10.2 years of use) compared with 33 nonuser controls.Main Outcome Measures Measures from 9 standard neuropsychological tests that assessed attention, memory, and executive functioning, and were administered prior to entry to a treatment program and following a median 17-hour abstinence.Results Long-term cannabis users performed significantly less well than shorter-term users and controls on tests of memory and attention. On the Rey Auditory Verbal Learning Test, long-term users recalled significantly fewer words than either shorter-term users (P = .001) or controls (P = .005); there was no difference between shorter-term users and controls. Long-term users showed impaired learning (P = .007), retention (P = .003), and retrieval (P = .002) compared with controls. Both user groups performed poorly on a time estimation task (P<.001 vs controls). Performance measures often correlated significantly with the duration of cannabis use, being worse with increasing years of use, but were unrelated to withdrawal symptoms and persisted after controlling for recent cannabis use and other drug use.Conclusions These results confirm that long-term heavy cannabis users show impairments in memory and attention that endure beyond the period of intoxication and worsen with increasing years of regular cannabis use.
Objective. —To assess whether frequent marijuana use is associated with residual neuropsychological effects.Design. —Single-blind comparison of regular users vs infrequent users of marijuana.Participants. —Two samples of college undergraduates: 65 heavy users, who had smoked marijuana a median of 29 days in the past 30 days (range, 22 to 30 days) and who also displayed cannabinoids in their urine, and 64 light users, who had smoked a median of 1 day in the last 30 days (range, 0 to 9 days) and who displayed no urinary cannabinoids.Intervention. —Subjects arrived at 2 PM on day 1 of their study visit, then remained at our center overnight under supervision. Neuropsychological tests were administered to all subjects starting at 9 AM on day 2. Thus, all subjects were abstinent from marijuana and other drugs for a minimum of 19 hours before testing.Main Outcome Measures. —Subjects received a battery of standard neuropsychological tests to assess general intellectual functioning, abstraction ability, sustained attention, verbal fluency, and ability to learn and recall new verbal and visuospatial information.Results. —Heavy users displayed significantly greater impairment than light users on attentional/executive functions, as evidenced particularly by greater perseverations on card sorting and reduced learning of word lists. These differences remained after controlling for potential confounding variables, such as estimated levels of premorbid cognitive functioning, and for use of alcohol and other substances in the two groups.Conclusions. —Heavy marijuana use is associated with residual neuropsychological effects even after a day of supervised abstinence from the drug. However, the question remains open as to whether this impairment is due to a residue of drug in the brain, a withdrawal effect from the drug, or a frank neurotoxic effect of the drug.(JAMA. 1996;275:521-527)
The purpose of this research was to examine the effects of cognitive impairment on the efficacy of substance abuse treatment outcome. Alcohol, drug, medical, legal, psychological, employment, and family functioning related treatment outcomes were examined for 26 cognitively impaired and 68 cognitively intact abusing outpatients. Subjects were enrolled in an intensive, 3-week, outpatient program for the treatment of their substance abuse. Subjects were administered a battery of neuropsychological tests prior to treatment onset, and outcome data were obtained at 1, 3, 6, and 12 months posttreatment entry. No significant between-group differences were found on any of the outcome measures, and significant treatment gains were observed across all problem domains in both groups. Subjects' largest improvements were made in the first month of treatment for alcohol, drug, legal, family, and psychological problems. Improvements for employment and medical problems were not observed until 6 months posttreatment. Success across domains was maintained through 12 months follow-up, with the exception of psychological problems; 12-month data indicated a return to thelevel observed at 30 days posttreatment for psychological problems, a level that reflected significant improvement from baseline functioning. A greater proportion of treatment dropouts (i.e., no follow-up data obtained after 30 days) were cognitively impaired as compared to treatment completers. These results suggest that this method of intensive substance abuse outpatient treatment is effective for cognitively impaired patients, an important finding given that research evaluating the efficacy of interventions for such patients is limited. Additionally, neuropsychological evaluation may be important in reducing treatment dropouts, as the present findings indicated that greater cognitive impairment was related to an increased likelihood of treatment dropout.
Reviews the role of the frontal lobes in cognition as illuminated by neuroimaging. The discussion in limited to those processes that are "cognitive" in the sense that they are not purely sensory or motor but require some elaboration of stimuli and a decision to be made about some aspect of the stimuli. The author only considers those areas that are part of the prefrontal cortex ( i.e., Brodmann's areas 8–11 and 45–47). Furthermore, only those experiments carried out on healthy, young Ss are considered, in an attempt to focus on the "normal" functioning of the prefrontal cortex. Finally, the author has included only those experiments that have utilized positron emission tomography to measure regional cerebral blood flow and have reported the results in terms of atlas coordinates. (PsycINFO Database Record (c) 2012 APA, all rights reserved)