Does bright light treatment influence affective processing?

Lead Research Organisation: University of Oxford
Department Name: Psychiatry


Background and Aims of Research
Bright light therapy is an effective treatment for seasonal affective disorders and non-seasonal depression (Golden et al., 2005; Lam et al., 2015; Oldham & Ciraulo, 2014; Özdemir et al., 2015). Despite having effect sizes in the order of that of antidepressant medications and fewer side effects, bright light treatment (BLT) appears relatively neglected in psychiatric research (Golden et al., 2005; Oldham et al., 2014). To date, there is little knowledge about how BLT acts to improve the symptoms of depression. Proposed physiological mechanisms include influences on the circadian clock, on secretion of melatonin, or on monoaminergic systems (Kronfeld-Schor & Einat, 2012; Neumeister et al., 2001), but the neuropsychological effects of BLT have not been described in detail yet. On a neuropsychological level, an important therapeutic target in depression seems to be the processing of emotion-related information. It has previously been shown that even short-term treatment with serotonergic and noradrenergic antidepressants positively biases emotional information processing despite the absence of improvements of mood (Arnone, Horder, Cowen, & Harmer, 2009; Harmer, Hill, Taylor, Cowen, & Goodwin, 2003; Harmer, Shelley, Cowen, & Goodwin, 2004). BLT has a similar efficacy (Golden et al., 2005; Lam et al., 2015; Oldham et al., 2014; Özdemir et al., 2015), and probably targets the same neurotransmitter systems as antidepressant drugs (Neumeister et al., 2001). It therefore seems an interesting question whether BLT also affects emotion-related cognitive processing. However, to date no published study has addressed this issue. During the DPhil program in Oxford my aim will be to fill this gap in the literature. I will draw on a previously established approach by Prof Catherine Harmer and colleagues, in order to study the effects of one-time and repeated BLT in healthy individuals (for details see Experiment 1 and 2 below). This will allow to dictly investigate the actions of BLT on emotional information processing, unconfounded by underlying psychopathological conditions. My research will reveal, whether BLT biases the processing of emotion related and social cues, and whether such effects can be measured in absence of improvements of mood and subjective state. Furthermore, the experiments will reveal whether one-time BLT is sufficient to lead to significant changes in emotional information processing. These findings would not only shed light on the neuropsychological effects of bright light therapy and how it might act to improve symptoms of depression,
but also provide important information regarding the general psychological effects of bright light exposure.


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