Using Pupil Dilation to Screen Depressed Patients for Remission Likelihood with CBT Treatment

Research indicates that cognitive behavior therapy (CBT) is an effective treatment for up to 60% of patients with Major Depressive Disorder (MDD). However, some patients are more likely to remit than others, depending on the severity of the disorder. It is important and beneficial to patients, clinicians, and third-party payers alike, therefore, that scientists identify those who will most likely benefit from treatment.

One facet of CBT treatment involves interrupting the “downward spiral” of automatic negative thoughts. While neuroimaging has shown that CBT influences this type of brain activity via sustained limbic activity and decreased prefrontal function, functional magnetic resonance imaging (fMRI) can be costly and time-consuming. A recent study by Siegle, et al. published in Biological Psychiatry proposes that pupillary response to negative words may be a cost-effective measure to predict the likelihood of remission for certain depressed patients treated with CBT. Previous research has shown that depressed patients have increased and sustained pupillary response to negative words and that this response reflects cognitive and emotional processes, including prefrontal control.

Patients (n=32) with recurrent MDD were recruited for the current study. Participants completed an emotion-identification task that required they identify certain words as positive, negative, or neutral.  Participants also completed a digit sorting task to assess executive control. Pupillary response was measured during these tests. Participants then received a 16-session CBT intervention. The Beck Depression Inventory (BDI) was used to determine which patients had achieved remission (i.e., a score of less than 10 on the BDI coupled with no diagnosis of MDD). To test whether pupillary response was related to limbic activity, fMRI data was used for the 20 subjects able to complete this part of the experiment.

In the current study, patients who exhibited lower pretreatment depressive severity had better remission rates. These patients also presented with increased and sustained pupillary response. These results suggest that increased pupillary response is related to higher remission rates. That is, patients with a higher level of pupillary response may be more likely to remit with CBT; those with lower scores may be less likely and might choose to pursue other, more intensive treatment options. Increased pupillary response also correlated with increased prefrontal activity, which can be linked to executive control and emotional regulation. Siegel, et al. conclude that measuring pupillary response may be a noninvasive, cost-effective, and quick (requiring less than 10 minutes) tool to help depressed patients and their providers decide on effective treatment.

Lead author, Greg Siegle, Ph.D., was selected and participated in our Beck Institute Scholars Program in 2007-2008.

Siegle, G.J., Steinhauer, S.R., Friedman, E.S., Thompson, W.S., Thase, M.E. (2011). Remission prognosis for cognitive therapy for recurrent depression using the pupil: Utility and neural correlates. Biological Psychiatry; 69: 726-733. doi:10.1016/j.biopsych.2010.12.041

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