The effects of inhalant misuse on attentional networks

The Alerting and Orienting Systems of Attention Are Modified by Cannabis Dependence

Attention allows us to select relevant information from the background. Although several studies have described that cannabis use induces deleterious effects on attention, it remains unclear if cannabis dependence affects the attention network systems differently.

OBJECTIVES

To evaluate whether customary consumption of cannabis or cannabis dependence impacts the alerting, orienting, and executive control systems in young adults; to find out whether it is related to tobacco or alcohol dependence and if cannabis use characteristics are associated with the attention network systems.

METHOD

One-hundred and fifty-four healthy adults and 102 cannabis users performed the Attention Network Test (ANT) to evaluate the alerting, orienting, and executive control systems.

RESULTS

Cannabis use enhanced the alerting system but decreased the orienting system. Moreover, those effects seem to be associated with cannabis dependence. Out of all the cannabis-using variables, only the age of onset of cannabis use significantly predicted the efficiency of the orienting and executive control systems.

CONCLUSION

Cannabis dependence favors tonic alertness but reduces selective attention ability; earlier use of cannabis worsens the efficiency of selective attention and resolution of conflicts.

Neuropsychiatric characterization of individuals with inhalant use disorder and polysubstance use according to latent profiles of executive functioning

BACKGROUND

Inhalant use disorder (IUD) is associated with deficits in executive functions (EFs). We described latent profiles of EFs and distribution of neuropsychiatric disorders and patterns of severity of use across these profiles.

METHODS

Individuals with IUD were recruited at community-based residential facilities for substance use treatment in Mexico City. Latent profile analysis was conducted with the following tasks: self-ordered pointing, Stroop, Iowa gambling, Wisconsin Card Sorting and Tower of Hanoi.

RESULTS

Three latent profiles were extracted from n = 165: lowest performances of inhibition of response and processing speed; lowest performance of self-monitoring, intermediate performance of inhibition of response and relatively spared processing speed; and intermediate performance of processing speed and self-monitoring, and relatively spared inhibition of response.

CONCLUSION

Between-group differences were observed mainly for antisocial personality disorder and lifetime suicidal. Findings remark the need for identifying distinct profiles of EFs within these populations to better understand the transdiagnostic heterogeneity of EFs.

Association of Cannabis With Cognitive Functioning in Adolescents and Young Adults: A Systematic Review and Meta-analysis

IMPORTANCE

Substantial shifts in perception and policy regarding cannabis have recently occurred, with use of cannabis increasing while its perceived harm decreases. One possible risk of increased cannabis use is poorer cognitive functioning, especially in youth.

OBJECTIVE

To provide the first quantitative synthesis of the literature examining cannabis and cognitive functioning in adolescents and young adults (with a mean age of 26 years and younger).

DATA SOURCES

PubMed, PsycInfo, Academic Search Premier, Scopus, and bibliographies of relevant reviews were searched for peer-reviewed, English-language studies from the date the databases began through May 2017.

STUDY SELECTION

Consensus criteria were used to determine study inclusion through abstract and manuscript review.

DATA EXTRACTION AND SYNTHESIS

This study followed Meta-analysis of Observational Studies in Epidemiology guidelines. Effect size estimates were calculated using multivariate mixed-effects models for cognitive functioning outcomes classified into 10 domains.

MAIN OUTCOMES AND MEASURES

Results from neurocognitive tests administered in cross-sectional studies were primary outcomes, and we examined the influence of a priori explanatory variables on variability in effect size.

RESULTS

Sixty-nine studies of 2152 cannabis users (mean [SD] age, 20.6 [2.8] years; 1472 [68.4%] male) and 6575 comparison participants with minimal cannabis exposure were included (mean [SD] age, 20.8 [3.4]; 3669 [55.8%] male). Results indicated a small overall effect size (presented as mean d) for reduced cognitive functioning associated with frequent or heavy cannabis use (d, -0.25; 95% CI, -0.32 to -0.17; P < .001). The magnitude of effect sizes did not vary by sample age or age at cannabis use onset. However, studies requiring an abstinence period longer than 72 hours (15 studies; n = 928) had an overall effect size (d, -0.08; 95% CI, -0.22 to 0.07) that was not significantly different from 0 and smaller than studies with less stringent abstinence criteria (54 studies; n = 7799; d, -0.30; 95% CI, -0.37 to -0.22; P = .01).

CONCLUSIONS AND RELEVANCE

Associations between cannabis use and cognitive functioning in cross-sectional studies of adolescents and young adults are small and may be of questionable clinical importance for most individuals. Furthermore, abstinence of longer than 72 hours diminishes cognitive deficits associated with cannabis use. Although other outcomes (eg, psychosis) were not examined in the included studies, results indicate that previous studies of cannabis in youth may have overstated the magnitude and persistence of cognitive deficits associated with use. Reported deficits may reflect residual effects from acute use or withdrawal. Future studies should examine individual differences in susceptibility to cannabis-associated cognitive dysfunction.

Abnormal white matter integrity and impairment of cognitive abilities in adolescent inhalant abusers

Inhalant abuse represents a major health problem especially among adolescents and young adults. However, less is known about white matter (WM) microstructure in adolescent inhalant abusers. In the present study, we used diffusion tensor imaging (DTI) to study WM changes in adolescent inhalant abusers compared with healthy controls. We also tested whether there was any relationship between WM integrity and neuropsychological measures in adolescent inhalant abusers. The study included 19 adolescent inhalant abusers and 19 healthy control subjects. Whole brain analysis of WM microstructure was performed using tract-based spatial statistics (TBSS) to detect abnormal WM regions between groups. Wisconsin card sorting test (WCST) and Stroop test were used to measure neuropsychological performance. We found that adolescent inhalant abuser group had significantly higher axial diffusivity (AD) values in left parietal, occipital and temporal WM than in healthy control group. Inhalant abuser and control groups did not differ significantly on fractional anisotropy (FA) and radial diffusivity (RD) values. Adolescent inhalant abusers showed worse performance when compared with control group in WCST and Stroop test. There was no significant correlation of AD values in significant clusters with neuropsychological test performances within the two groups. We only found discrete impairments in neuropsychological test performance and WM integrity in adolescent inhalant abusers compared with healthy control subjects and we were not able to demonstrate a direct correlation between WM alterations and neurocognitive performance. Future work is required to longitudinally evaluate brain abnormalities through methods assessing brain structure, function and connectivity.

A signal detection analysis of executive control performance among adolescent inhalant and cannabis users

BACKGROUND

Inhalant users have multiple comorbid issues (e.g., polydrug use) that complicate identifying inhalant-specific cognitive deficits.

OBJECTIVES

The aim of the present study was to use signal detection theory to identify inhalant-specific differences in executive control.

METHODS

We examined three well-matched groups: 19 inhalant users, 19 cannabis users, and 19 controls using Stroop and Go/No-Go tasks.

RESULTS

Inhalant users demonstrated significantly lower d-prime scores relative to controls, but not cannabis users, on both tasks, suggesting possible executive deficits relative to controls. CONCLUSIONS/IMPORTANCE: The results of this study raise questions regarding inhalant toxicity and the vulnerability of the adolescent brain to drugs of abuse.

Executive attention impairment in adolescents with schizophrenia who have used cannabis

OBJECTIVE

Repeated exposure to cannabis in nonpsychotic adolescents is associated with impairments in executive control of attention, similar to those observed in young adults with first-episode schizophrenia. To assess the impact of recurrent exposure to cannabis on cognitive function, this study characterized attention performance in both nonpsychotic adolescents and adolescents with early-onset schizophrenia (EOS).

METHOD

The Attention Network Test, a standard procedure that estimates the functional state of neural networks controlling the efficiency of three different attentional behaviors (alerting, orienting, and executive attention), was administered to four groups of participants: (1) adolescents with EOS and comorbid cannabis use disorder (EOS+CUD; n=18), (2) "Pure" schizophrenia (EOS; n=34), (3) "Pure" cannabis use disorder (CUD; n=29), and (4) Healthy controls (HC; n=53). Task performance was examined with a 2×2 design (EOS+ versus EOS- and CUD+ versus CUD-) using multivariate analysis of covariance. Correlative analyses were conducted between executive attention performance and measures of surface area in the right anterior cingulate cortex.

RESULTS

A significant EOS×CUD interaction was observed. In the executive attention network, adolescents with EOS+CUD showed reduced efficiency relative to adolescents with pure EOS, whereas no group differences were found between adolescents with pure CUD and HC. Less efficient executive attention was significantly associated with smaller surface area in the right caudal anterior cingulate cortex in EOS+CUD.

CONCLUSIONS

These preliminary data suggest that the presence of CUD has a moderating effect on attentional performance in adolescents with schizophrenia compared to nonpsychotic adolescents. These deficits could have a role in difficulties with self-regulation and predisposition to substance misuse in this patient group. The anatomic substrate of this cognitive deficit may be related to surface area in the right caudal anterior cingulate cortex.