Is the Startle Reflex a Potential Endophenotype for Anxiety Disorders?

Authors

• M Tsui
• A Schmitz
• A Van Meter
• C Grillon
• K Merikangas

Abstract

Potentiation of the startle reflex through various strategies to elevate emotional states has been a valuable tool to identify circuits underlying fear and anxiety states. However, there is limited knowledge of its heritability in humans. The present study sought to investigate whether the startle reflex may comprise a biomarker of anxiety risk, as well as a potential endophenotype of anxiety disorders in humans. We assessed fear-potentiated and anxiety-potentiated startle using a predictable and unpredictable threat paradigm in the NIMH Family Study of Mood Spectrum Disorders. Startle reflex, heart rate, pulse, and skin conductance were measured during the task. The sample included 90 families, with 169 adult and child relatives, of whom about half were female. The chief questions were: (1) Is there an association between the components of startle in probands and relatives?; (2) Do the components of startle cluster within families (e.g., heritability)?; (3) Are startle components associated with mood and anxiety disorder subtypes; and (4) Is there familial coaggregation of startle and anxiety disorders, or subtypes thereof? Findings indicated that all measures of the startle reflex including habituation, baseline, and conditioned startle were familial (Proband-relative associations = p

Scientific Focus Area: Epidemiology

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