Anxiety sensitivity correlates with two indices of right anterior insula structure in specific animal phobia.
BACKGROUND
Anxiety sensitivity (AS) is a dispositional trait involving fear of anxiety-related symptoms. Functional imaging research suggests that the activity of the anterior insular cortex, particularly the right insula, may both mediate AS and play a role in the pathophysiology of phobias. However, no imaging studies have examined whether AS relates to insula morphology. We examined whether AS was significantly correlated with right anterior insula volume and thickness among adults with specific animal phobia (SAP) and healthy comparison (HC) subjects.


METHODS
Nineteen adults with SAP and 20 demographically group-matched HC subjects underwent magnetic resonance imaging at 3 Tesla. Subjects also completed the Anxiety Sensitivity Index (ASI). Regression and correlation analyses examined ASI scores in relation to anterior and posterior insular cortex volume and thickness within and across subject groups.


RESULTS
SAP subjects had significantly higher ASI scores than HC, but did not differ in terms of insula volumes or thickness. ASI scores predicted right anterior insula thickness in SAP but not HC subjects, and right anterior insula volume in the sample as a whole. Correlations of ASI scores with the anterior and posterior insula volume and thickness were not significant in either group.


CONCLUSIONS
These findings suggest that the right anterior insular cortex size is a neural substrate of AS within specific phobia, rather than an independent diagnostic marker of the disorder. Future investigations should examine whether heightened AS represents a shared intermediate phenotype across anxiety disorders, manifesting functionally as increased insular reactivity and clinically as a fear of anxiety symptoms.
Neuroimaging Center, McLean Hospital, Belmont, Massachusetts 02478, USA. irosso@hms.harvard.edu
Isabelle M
IM
Rosso
Nikos
N
Makris
Jennifer C
JC
Britton
Lauren M
LM
Price
Andrea L
AL
Gold
David
D
Zai
John
J
Bruyere
Thilo
T
Deckersbach
William D S
WD
Killgore
Scott L
SL
Rauch
D000328:Adult; D000818:Animals; D001143:Arousal / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000473:pathology / Q000503:physiopathology*; D002605:Character; D004292:Dominance, Cerebral / Q000502:physiology*; D005239:Fear / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D009929:Organ Size / Q000502:physiology; D010698:Phobic Disorders / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D012377:Rodentia; D012911:Snakes; D013112:Spiders; D055815:Young Adult