Article: Cannabis and Inhibition

Question 1

why did they conduct the research?

Answer 1

Previous studies have suggested that chronic cannabis use has been associated with increased blood oxygen level–dependent (BOLD) response during a response inhibition task; however, these studies primarily included males and had very small samples

Question 2

Females and neurocognitive deficits from cannabis

Answer 2

• In animal models, THC exposure has been shown to down-regulate CB1 receptors more in female brains
  compared with that in their male counterparts
• findings suggest that female populations may be more susceptible to neurocognitive deficits from cannabis

Question 3

purpose of the study

Answer 3

• to investigate the relationship between cannabis use and brain functioning during an inhibitory task and how these effects may differ between males and females following a minimum of 2 weeks of monitored abstinence
• examine how cannabis
  use may alter functional activity between male and female
  users

Question 4

what did they hypothesize?

Answer 4

despite having similar
behavioral performance on an fMRI task, cannabis users will demonstrate significantly greater BOLD responses compared with controls during correct inhibitions on the Go-NoGo task in various brain regions

Question 5

MINI psychiatric interview

Answer 5

used to prevent comorbid psychiatric history from confounding results

Question 6

Timeline Followback interviews

Answer 6

measure substance use patterns over the past year

Question 7

mRI data processing

Answer 7

• Data points of incorrect responses on the Go-NoGo trial were removed from data in order to compare correct calm Go-NoGo stimuli across
  cannabis users and control
• only examined correct inhibitory responses to the calm NoGo stimuli, bc calm is considered neutral
• Fearful and happy NoGo stimuli were not incorporated into the analyses to not confound BOLD responses with potential responses to emotional-based stimuli

Question 8

fMRI affective No-Go task

Answer 8

• completed a Go-NoGo task featuring faces expressing feelings of happy, fearful, or calm
• two facial expressions were
  used within a trial
• were told what particular stimuli/expression they should respond to by hitting a target box (Go), and what stimuli/expression they should stop themselves from
  responding and hitting the target box (NoGo)
• task that incorporates facial expressions as stimuli for participants to respond to, may capture a more ecologically valid approach to response inhibition

Question 9

Chi-Square test

Answer 9

statistical method used to examine whether there is a significant association between categorical variables
ex. researcher wants to test if the preference for a type of snack (chocolate, chips, or fruit) is related to age group (children, teenagers, and adults) test used to determine if snack preference and age group are related

Question 10

Analysis of Variance (ANOVA)

Answer 10

statistical technique used to compare means across multiple groups to determine if there are any statistically significant differences among them

Question 11

what was used to examine group differences?

Answer 11

voxel by voxel ANCOVA

Question 12

How does voxel by voxel
ANCOVA work?

Answer 12

• ANCOVA tests for differences between two or more groups (as in ANOVA) but adjusts for one or more covariates (continuous variables) that might affect the dependent variable
• apply ANCOVA at each voxel to evaluate how brain activity (or structure) relates to the dependent variable, adjusting for confounding variables
• Statistical maps are created for each voxel to show significant brain regions where the variable of interest is associated with brain activity or structure, independent of the covariates

Question 13

How did they investigate whether gender moderates effect between cannabis use and BOLD responses?

Answer 13

incorporated models including gender, cannabis use group, and genderby-cannabis use group interactions with past year alcohol
and past year nicotine use as the covariate within all
analyses

Question 14

post hoc analyses

Answer 14

• performed after an experiment to explore or identify differences between groups
• used to explore further and interpret significant findings

Question 15

Post hoc analyses in this study

Answer 15

• Age of first cannabis use has previously been indicated as an important factor in cannabis users and response inhibition
• length of abstinence in relation to increased BOLD responses
  has also been marked as a variable of interest
  -utilized to examine beta values from significant clusters and age of first cannabis use, age of first regular cannabis use (i.e., using cannabis once a week), and length of
  cannabis abstinence in cannabis users

Question 16

Finding from the study

Answer 16

• similar behavioral task performance
• adolescent and young adult cannabis users demonstrated greater
  BOLD activation within regions associated with response inhibition even after a minimum of 2 weeks of monitored abstinence
• Gender did not moderate these effects

Question 17

Limitations

Answer 17

• greater BOLD activity observed in cannabis users may be premorbid in nature; inherent brain differences in these regions may make individuals more susceptible to using cannabis in the adolescent and young adult years
• primarily Caucasian, relatively average to high average
  education levels, and did not have comorbid medical, physical, neurologic, or psychiatric disorders
• narrrows generalizability of the study