Recurrence of major depressive disorder is predicted by inhibited startle magnitude while recovered

Major depressive disorder, for some, follows a chronic relapsing course. However, no reliable marker has been established that allows the identification of this sub-group of patients. Preliminary findings suggest that baseline startle magnitude may be such a marker. This study evaluated whether differences in baseline startle magnitude during remission could prospectively predict depressive symptomatology and recurrence.

A group of previously depressed individuals (n=25), who were in full remission at the time of testing, had their startle reflex measured via surface EMG electrodes on the left orbicularis oculi muscle. These people were then followed-up 2 years later and their depressive symptomatology during the intervening period was assessed using the psychiatric ratings scale of the Longitudinal Interval Follow-up Evaluation (LIFE; [Keller, M.B., Lavori, P.W., Friedman, B., Nielsen, E., Endicott, J., McDonald-Scott, P., et al. (1987). The Longitudinal Interval Follow-up Evaluation. A comprehensive method for assessing outcome in prospective longitudinal studies. Arch. Gen. Psychiatry, 44(6), 540-548]) and incidents of recurrence assessed using the Structured Clinical Interview for DSM-IV (SCID-I/P; [First, M.B., Spitzer, R.L., Gibbon, M., & Williams, J.B.W. (2001). Structured clinical interview for axis 1 DSM-IV disorders. New York: New York State Psychiatric Institute]).

It was found that a relatively attenuated startle response at initial assessment was strongly predictive of both depressive symptomatology and those who would experience relapse.

This study has a relatively small sample size that limits the degree to which a thorough co-variant analysis can be conducted and also makes the analysis of gender-based difference impracticable. Additionally, as no healthy control group is included, we report a relative rather than absolute attenuation of startle to be indicative of symptom severity and recurrence proclivity.

These preliminary findings suggest that an attenuated startle response may have utility as an endophenotypic marker of risk for recurrence of Major Depression and residual sub-syndromal symptomatology. Such a marker may facilitate the early identification and treatment of those most at risk of recurrent Major Depression.