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P1-E-40 Reduced Functional Eciency Within the Working Memory Network in Adolescents Predicts Cannabis
Initiation Four Years Later While Cannabis Use Does Not Lead to Future Changes in Working Memory Activation
Mona Darvishi1, Charles Ferris2, Ping Bai1, Bethany Boettner1, Christopher Browning1, Dylan Wagner1, Baldwin Way1
1The Ohio State University, 2McGill University
The bulk of imaging studies on the relationship between neural activity during working memory and cannabis use have been
cross-sectional, leaving questions about whether brain activity dierences between cannabis users and non-users reect
pre-existing vulnerabilities (vulnerability model) or result from neuroadaptive changes due to cannabis exposure (toxicity
/neuroadaptation model). The present work takes advantage of a longitudinal sample to (1) determine if neural activity in
working memory-related ROIs at baseline predicts cannabis initiation four years later (vulnerability model) and (2) determine if
cannabis use over this period predicts changes over time in working memory-related neural activity (neuroadaptation model).
At time point 1, the study sample was 177 adolescents (100 females) from the Adolescent Health and Development in Context
(AHDC) study, with an initial average age of 15.98 years (SD = 2.06). For the cross-sectional analysis at time point 1, a standard
fMRI GLM model was used with group-level models (2-Back vs. 0-back) to generate dierentiated activation clusters (voxel-wise
uncorrected p < 1x10-13) for which a 6mm sphere around each peak voxel was generated (n=14). After FDR correction, any
lifetime cannabis use positively correlated with neural activity in the left superior medial gyrus (r = .27, p = .005), inferior parietal
lobule (r = .22, p = .019), insula/inferior frontal gyrus (r = .23, p = .019), and right middle frontal gyrus (r = .20, p = .022). For aim
1 (vulnerability model), logistic regression analyses among youth who had never used cannabis at baseline (n=109) assessed if
neural activity in these 4 ROIs predicted cannabis initiation four years later, controlling for working memory performance as
well as alcohol/cigarette use, household income, sex, age, and race. At follow-up (mean age = 19.93 years), 36 participants
had initiated cannabis use, while 73 had not. Increased activation in the left superior medial gyrus (OR = 2.23, CI = 1.09–5.33,
p = .044), left inferior parietal lobule (OR = 3.79, CI = 1.65–10.41, p = .004), left insula/inferior frontal gyrus (OR = 1.80,
CI = 0.65–7.36, p = .020), and right middle frontal gyrus (OR = 3.20, CI = 1.40–8.64, p = .011) predicted cannabis initiation
4 years later. Comparable Results (all p’s < .05) for these 4 ROIs were obtained when using a measure of cannabis use in the
last 12 months. These Results provide robust evidence for the predictive role of neural activation in these regions on future
cannabis initiation when controlling for behavioral performance. For aim 2 (neuroadaptation model), multiple linear regression
analyses were conducted for those who had neuroimaging data at both time points (n = 63) using the same ROIs, controlling
for baseline activity and the same covariates. Neither a lifetime history of cannabis use nor cannabis use in the last 12 months
predicted altered brain functioning over time in these ROIs (all p’s > .29). These Results indicate that cannabis use may not
result in signicant changes in brain functioning within the observed timeframe. However, heightened activation for the same
level of behavioral performance in specic brain regions during the N-Back task may indicate increased susceptibility to cannabis
initiation, independent of other risk factors. This research is important for distinguishing risk factors from the outcomes of
substance use.
P1-E-41 Predicting Longitudinal Anxiety in Adolescents Using Mixed Eects Random Forest Regression
Paola Odriozola1, Amanda Baker2, Claire Waller1, Nancy Le1, Savannah Lopez1, Katie Bessette1, Lucina Uddin1, Tara Peris1,
Adriana Galvan1
1University of California, Los Angeles, 2Florida International University
Background and Aims: Many psychiatric disorders emerge during adolescence, with anxiety being the most common—
aecting as many as 1 in 3 youths (Beesdo et al., 2009; Kessler et al., 2005). Understanding the factors that shape the persistence
and remittance of anxiety across development remains limited. Using machine learning methods with longitudinal behavioral,
clinical, and fMRI data from adolescents, we took a data-driven approach to investigate whether we could predict anxiety
symptoms years later. We hypothesized that we could predict future anxiety symptoms with high precision, and that functional
connectivity of brain regions previously shown to be implicated in anxiety (e.g., amygdala, hippocampus, insula, dorsal anterior
cingulate cortex, medial prefrontal cortex (mPFC), and the default-mode network) would be of highest importance in the model.
Methods: 132 adolescent participants ages 9-14 completed the Development of Anxiety in Youth Study (Galván & Peris, 2020),
a prospective longitudinal study that occurred annually for 3 years. Participants completed a resting state fMRI scan, the Screen
for Child Anxiety Related Disorders (SCARED) child report version (Birmaher et al., 1997), and demographic questionnaires at
each visit. Using the resting state data, we computed a functional connectivity matrix between a subset of 53 ROIs from a
functionally-dened atlas (Seitzman et al., 2020), which were selected based on a recent meta-analysis of machine learning
studies of anxiety disorders (Rezaei et al., 2023). We submitted scaled data to a stochastic mixed eects random forest
regression analysis (sMERF) implemented in R using the LongituRF package (Capitaine et al., 2021). The predictors consisted of
1086 variables including functional connectivity values and demographic variables (i.e., age, sex at birth, race, ethnicity, family
income, and IQ); and the outcome of interest was SCARED total score. We used 80% of the data for training, and the other 20%
for testing the model. Prediction errors were calculated as root mean square error with 25 training/test set random splits.
Results: Prediction of future anxiety symptoms using sMERF yielded a root mean square error of 0.97. The top 5 variables that
yielded the highest relative importance (i.e., highest predictive value) in the model included (in order of relative importance) were
functional connectivity of: (1) the right posterior cingulate cortex and the right orbitofrontal cortex; (2) the left mPFC and the right
mPFC; (3) the right insula and the right cerebellum; (4) the left insula and the right cerebellum; and (5) the right superior parietal
lobe and the left cerebellum.
Conclusions: Results from the present study suggest that resting functional connectivity between regions often overlooked
in studies of anxiety—such as the cerebellum and the superior parietal lobe—as well as regions often included in studies of
anxiety—such as the insula and mPFC—may play a large role in predicting anxiety symptoms over time. Increasing our