Modulation of sensitivity to light as a mechanism for antidepressant treatment efficacy
Grantholders
Dr Sean Cain
Monash University, Australia
Dr Elise McGlashan
Monash University, Australia
Prof Suresh Sundram
Monash University, Australia
Sharna Jamadar
Monash University, Australia
Dr Richa Saxena
Massachusetts General Hospital, United States
Prof Ian Hickie
University of Sydney, Australia
Dr Jacob Crouse
University of Sydney, Australia
Project summary
Despite being among the most commonly prescribed medications, the mechanism of action for antidepressants remains unknown. Our hypothesis is that selective serotonin reuptake inhibitors (SSRIs), the most commonly prescribed class of antidepressants, are effective due to effects on circadian function. We have shown that SSRIs amplify the non-visual effects of light. This potentially results in increased mood-elevating effect of light, but also an increased vulnerability to sleep and circadian disruption by light at night. We propose to investigate how SSRI efficacy may be due to an individual's balance of these positive and negative effects. Our comprehensive sleep and circadian phenotyping study will address the following aims:
- What is the effect of chronic SSRI use on multiple measures of non-visual light sensitivity (including melatonin suppression, phase shifting, fMRI-measured responses to light, pupillary light responses), and common markers of circadian function (circadian phase, amplitude)?
- Test the hypothesis that increased light sensitivity is predictive of better SSRI treatment efficacy for depression. - Test the hypothesis that sleep regularity and light-dark patterns interact with changes in light sensitivity to predict SSRI treatment efficacy for depression.
- Are there baseline circadian characteristics (circadian phase, amplitude, markers of light sensitivity, genetics) that can predict better SSRI treatment efficacy?