Date of Award

Spring 2020

Degree Type



Chemistry and Biochemistry

Director of Thesis

Jessica Klusek

Second Reader

Carly Moser


Background: The FMR1 premutation, which occurs when there is an expansion of 55 -200 repeats of the CGG trinucleotide on the FMR1 gene, is associated with an increased risk for anxiety disorders. Indices of autonomic regulation may prove to be useful biomarkers for psychopathological risk, including stress and anxiety. In the general population, diminished habituation to a startle response is linked to a variety of psychological disorders, including anxiety, yet little is known about this relationship in those with the FMR1 premutation. Given the increased risk for anxiety in those with the FMR1 premutation, the present study aims to examine the relationship between the startle response and psychiatric vulnerability. Research Questions: (1) Is there a difference among women the FMR1 premutation and control women regarding habituation when taking into account various cardiac indicators? (2) Are any of the cardiac indicators of the initial startle probe associated with the severity of generalized anxiety symptoms in women with the FMR1 premutation? Methods: Participants included 31 women with the FMR1 premutation and 16 neurotypical control women aged 35-75 years. Participants completed a startle probe task in which they were exposed to 10 pure tone auditory probes through headphones. Participant’s heart activity was recorded for the duration of the task. Participants also filled out the Beck Anxiety Inventory, which is a self-reported questionnaire that indicates current anxiety symptoms. Results: Parasympathetic reactivation was found to be significant with a main effect of group (F [1, 34] = 5.47, p = 0.025), in which the control had higher parasympathetic reactivation. Additionally, it was observed that severity of anxiety symptoms increased as parasympathetic reactivation increased at the initial startle for the premutation group (F [1, 22] = 4.66, p = 0.043, R2 = .18). Conclusion: The premutation group had a blunted response during the parasympathetic reactivation which indicates autonomic dysregulation. Additionally, habituation did not occur in either group to the reoccurring startles when the heart rate was used as the measure. Lastly, as the severity of anxiety symptoms increased, the parasympathetic reactivation increased. Future studies could investigate the initial startle to look at the initial cardiac reactivity in the premutation group.

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