Supplemental Information

Price et al.: Deficient prefrontal attentional control in late-life generalized anxiety disorder: An fMRI investigation

Methods

Clinical assessments. Participants were required to be right-handed; able to read and write in English; free of anxiolytic and

antidepressant medications for at least 6 months; to have normal color vision; have no self-reported brain disease, dementia,

complicated or poorly-controlled diabetes, terminal illness, seizure disorder, or history of stroke; and to meet MRI safety

requirements. After written consent was obtained, all participants were assessed for current and lifetime DSM-IV Axis I

psychopathology via the Structured Clinical Interview for DSM-IV (SCID)1. Assessors were graduate students (Master’s level or

beyond) who completed formal training to reliability on the SCID. Based on a random sample of 8 audiotaped SCID interviews rated

blindly by the clinical supervisor, interrater reliability was 100% (=1.0). GAD participants were required to be free of any current

comorbid Axis I disorder. Past psychiatric diagnoses other than GAD were permitted, with several exceptions: 1) no substance use

disorders within the past 5 years; 2) no major depressive episodes within the past 3 years; 3) no lifetime psychotic disorders; 4) no

lifetime manic episodes 5) no mental retardation. Past diagnoses in the final sample included major depression (n=5), social phobia

(n=1), specific phobia (n=1), and posttraumatic stress disorder (n=1). Ten participants (63%) were free of any lifetime psychiatric

disorders other than GAD. During the SCID interview, participants were specifically asked about the presence of two health

conditions that are known to compromise PFC integrity: diabetes and hypertension2,3. Participants also completed a battery of self-

report symptom questionnaires including the Penn State Worry Questionnaire (PSWQ)4, the Generalized Anxiety Disorder

Questionnaire for DSM-IV (GAD-Q-IV)5, and the Beck Depression Inventory (BDI)6.

Emotional Stroop task. Words were printed in red or green ink and participants responded by pressing a button with their

right (red) or left (green) thumb. Because an older adult sample was tested, color options were limited to red and green to minimize

difficulty associated with remembering the button corresponding to the appropriate color. Ten practice trials were completed outside

the fMRI scanner. Word stimuli were presented in a large (48 pt), bold font, to maximize readability given our participants’ age range.

The eStroop word lists were adapted from eStroop studies of younger GAD7. The negative word list was comprised of an equal

number of anxiety and depression terms, consistent with the finding that both threat- and depression-related material elicits an

interference effect in GAD patients7,8. Although word ratings were not acquired from participants in the present study, an independent

sample of older adults (n=64; mean age=68; range=60-83) rated the words on pleasantness and arousal using a 7-point Likert-like

scale and confirmed that the anxiety and depression terms did not differ from one another on either dimension of emotionality (p’s

> .3), while both lists differed as expected from neutral words on both dimensions (p’s < .001).

Emotional Stroop behavioral data analysis. Trials with incorrect color identification responses or no response constituted

1.5% of all trials. Error rates did not differ by group (p=.20) nor exceed 4% for any individual. Due to the experimental design, which

restricted RTs to a maximum of 2000 ms, RT outliers were removed on the low end of the distribution only. Low outliers were

removed using a Winsorizing procedure9, in which the lowest 1% of RTs (across all participants) were replaced with the next lowest

value in the distribution of scores.

Mediation Analysis. The Multilevel Mediation and Moderation (M3) Toolbox

(http://www.columbia.edu/cu/psychology/tor/mediation.html) was used to conduct statistical tests of correlation coefficients and to

perform single-level mediation analysis based on a standard 3-variable path model10 with an additional test for the indirect effect of the

mediator. In this approach, M is considered a mediator of the relationship between X and Y if and only if: 1) X is related to Y (path c);

2) X is related to M (path a); 3) M is related to Y, controlling for X (path b); and 4) the effect of X on Y controlling for M (path c’) is

significantly smaller than the direct effect of X on Y (c – c’ > 0). A bootstrapping algorithm implemented in M3 was used to test for

statistical significance11. All variables were inspected for outliers and to ensure a unimodal distribution across the two groups.

ResultsTable S1

Within-group comparisons of BOLD signal for generalized anxiety disorder and non-anxious control participants: All significant

clusters

Region Location of peak voxel Hemisphere x y z

Cluster extent (Number of voxels) Peak Z

Negative > NeutralGAD group

No significant clusters

NAC group

Retrosplenial Cortex/ Precuneus/ Posterior Cingulate

L Precuneus L & R -10 -56 24 1556 4.58

Dorsomedial PFC R Superior Frontal Gyrus L & R 10 54 32 941 4.25

Ventrolateral PFC L Inferior Frontal Gyrus L -50 26 6 104 3.26

Neutral > NegativeGAD group

Dorsolateral PFC R Inferior Frontal Gyrus R 48 26 20 253 4.27

Dorsolateral PFC L Middle Frontal Gyrus L -40 28 40 103 3.70

NAC group

Inferior Parietal Lobule R Inferior Parietal Lobule R 34 -48 42 435 4.58

Amygdala/hippocampus L Basolateral Amygdala L -24 -2 -26 325 4.49

Amygdala (applying anatomical mask)

L Basolateral Amygdala L -24 -2 -26 117 4.49

Superior/Middle Temporal Gyrus

R Superior Temporal Gyrus

R 46 -42 16 145 4.05

Supramarginal Gyrus R Supramarginal Gyrus R 60 -30 38 300 3.98

Cerebellum Cerebellar Vermis L & R 0 -72 -22 154 3.77

Middle/Inferior Temporal Lobe R Middle Temporal Lobe R 46 -24 -12 201 3.68Note: Coordinates for peak voxels are presented in Montreal Neurological Institute (MNI) space. Anatomical mask for the amygdala (left and right) created using SPM’s Anatomy toolbox and small volume corrected at p < .05. All other findings are from unrestricted whole brain analysis with map-wise error rate p < .05. BOLD = blood-oxygen-level dependent; PFC = prefrontal cortex; GAD = generalized anxiety disorder; NAC = non-anxious control.

Table S2 Between-group comparisons of BOLD signal for generalized anxiety disorder and non-anxious control participants during the

negative-neutral run (negative>neutral contrast): All significant clusters

Region Location of peak voxel Hemisphere x y z

Cluster extent (Number of voxels) Peak Z

NAC > GAD Dorsolateral PFC L Inferior Frontal Gyrus L -58 18 24 112 3.66

Rostral Dorsolateral PFC R Superior Frontal Gyrus R 22 38 44 113 3.27

Brainstem/ Parahippocampal Gyrus/ Cerebellum

L Parahippocampal Gyrus L -22 -28 -24 130 3.13

GAD > NAC Supramarginal Gyrus R Supramarginal Gyrus R 60 -30 40 161 3.70

Middle Temporal Lobe R Middle Temporal Lobe R 48 -26 -12 201 3.67

Cerebellum Cerebellar Vermis L & R -2 -74 -22 103 3.46

Amygdala (applying anatomical mask)

L Basolateral Amygdala L -24 -2 -26 18 3.10

Note: Coordinates for peak voxels are presented in Montreal Neurological Institute (MNI) space. Anatomical mask for the amygdala (left and right) created using SPM’s Anatomy toolbox and small volume corrected at p < .05. All other findings are from unrestricted whole brain analysis with map-wise error rate p < .05. PFC = prefrontal cortex; GAD = generalized anxiety disorder; NAC = non-anxious control.

Table S3 Between-group comparisons of BOLD signal for generalized anxiety disorder and non-anxious control participants during the

negative-neutral run (negative>neutral contrast) in PFC and amygdala, covarying mean RT, age, gender, and BDI

Region Location of peak voxel Brodmann’s areas

x y z

Cluster extent (Number of voxels) Peak Z

NAC > GAD Dorsolateral PFC L Inferior Frontal Gyrus 45, 46 -56 22 22 102 2.93

Rostral Dorsolateral PFC R Superior Frontal Gyrus 8, 9 22 40 42 109 3.23

GAD > NAC Amygdala (applying anatomical mask)

L Basolateral Amygdala -24 -2 -26 20 2.86

Note: Coordinates for peak voxels are presented in Montreal Neurological Institute (MNI) space. Anatomical mask for the amygdala

(left and right) created using SPM’s Anatomy toolbox and small volume corrected at p < .05. All other findings are from unrestricted

whole brain analysis with map-wise error rate p < .05. PFC = prefrontal cortex; GAD = generalized anxiety disorder; NAC = non-

anxious control; RT = reaction time; BDI = Beck Depression Inventory.

Table S4 Within-group comparisons of BOLD signal for generalized anxiety disorder and non-anxious control participants in PFC and amygdala, covarying mean RT, age, gender, and BDI

Region Location of peak voxel Brodmann’s areas

x y z

Cluster extent (Number of voxels) Peak Z

Negative > NeutralGAD group

No significant clusters

NAC group

Dorsomedial PFC R Superior Frontal Gyrus 9, 10 12 54 28 256 3.45

Ventrolateral PFC L Inferior Frontal Gyrus 45, 47 -38 25 6 102 3.39

Neutral > NegativeGAD group

Dorsolateral PFC R Inferior Frontal Gyrus 45, 46 62 22 16 105 3.68

Dorsolateral PFC L Middle Frontal Gyrus 9 -50 28 10 108 3.12

NAC group

Amygdala/hippocampus L Basolateral Amygdala -24 -2 -26 152 3.51

Amygdala (applying anatomical mask)

L Basolateral Amygdala -24 -2 -26 94 3.51

Note: Coordinates for peak voxels are presented in Montreal Neurological Institute (MNI) space. Anatomical mask for the amygdala (left and right) created using SPM’s Anatomy toolbox and small volume corrected at p < .05. All other findings are from unrestricted whole brain analysis with map-wise error rate p < .05. Cluster extents reported for post-registration voxels (2mm3). BOLD = blood-oxygen-level dependent; PFC = prefrontal cortex; GAD = generalized anxiety disorder; NAC = non-anxious control.

Table S5 Regression analyses of individual covariates

Region Location of peak voxel Hemisphere

x y z

Cluster extent (Number of voxels) Peak Z

Positively related to BDI Supramarginal Gyrus R Supramarginal Gyrus R 64 -30 38 198 4.12

Negatively related to BDI No significant clusters

Positively related to Age Fusiform Gyrus L Fusiform Gyrus L -44 -50 -20 105 4.10

Middle Temporal Gyrus L Middle Temporal Gyrus L 58 -12 -10 423 4.04

Superior Temporal Gyrus R Superior Temporal Gyrus R -56 -10 -12 149 4.29

Negatively related to Age No significant clusters

Activation greater in women No significant clusters

Activation greater in men No significant clustersNote: Coordinates for peak voxels are presented in Montreal Neurological Institute (MNI) space. All findings are from unrestricted whole brain analysis with map-wise error rate p < .05. BDI = Beck depression inventory; PFC = prefrontal cortex.

Discussion

Findings in additional regions. In addition to PFC and limbic regions, a number of posterior regions were also implicated (Tables

S1 & S2). During negative words as compared to neutral, the NAC group alone showed greater activation of a posterior cortical

midline region encompassing portions of the retrosplenial cortex, precuneus, and posterior cingulate, regions that are functionally and

structurally interconnected with the medial PFC and DLPFC as well as with limbic structures including the hippocampus,

parahippocampus, and thalamus12,13 and thus may have played a role in integrating and translating information between these regions.

The NAC group also showed decreases during negative words in a network of posterior right hemisphere regions (inferior

parietal lobule including the supramarginal gyrus and temporoparietal junction; superior, middle, and inferior temporal gyrus). Right

posterior activity has been associated with an emotional surveillance system that ordinarily becomes engaged in the presence of

emotionally salient information, particularly threat-related material14. Furthermore, right inferior parietal lobule regions including the

supramarginal gyrus/temporoparietal junction have been widely implicated in the bottom-up capture of visual attention15 and tend to

be deactivated when top-down attention is engaged, allowing for adaptive ‘filtering out’ of stimulus-driven distraction16. Thus, the

bottom-up emotional surveillance and attentional capture functions of these regions may have been successfully down-regulated by

the NAC group during negative blocks, in order to ensure no intrusions from task-irrelevant emotional processing. The NAC group

also showed decreases during negative words in the bilateral posterior cerebellum including the cerebellar vermis, which has been tied

to emotional processing17. Thus, consistent with the decreases seen in left limbic regions, these decreases may collectively have

supported the NAC group’s behavioral efficiency during negative words—an efficiency that the GAD group failed to match.

Findings from covariate analyses. The addition of BDI, age, or gender as covariates in the primary within- and between-group

models did not impact the inclusion or exclusion of any of the clusters reported in Tables 2-3 of the main text, although each covariate

resulted in minor fluctuations in the location of the peak voxel and the number of voxels included in each cluster (Tables S3-S4). To

further examine the role of these covariates in our data, we also ran regression analyses for each covariate separately across the full

combined sample (NACs and GADs). Table S5 includes significant clusters of brain activation negatively and positively correlated

with each covariate across all participants during the eStroop task. The results are non-significant for most analyses and show no

overlap with the principle findings discussed in the main text, further suggesting that our results are not confounded by the effects of

depression, age, or gender.

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