Illuminating the way: the role of bright light therapy in the treatment of depression.

INTRODUCTION: Despite the growing number of different therapeutic options, treatment of depression is still a challenge. A broader perspective reveals the benefits of bright light therapy (BLT). It stimulates intrinsically photosensitive retinal ganglion cells, which induces a complex cascade of events, including alterations in melatonergic, neurotrophic, GABAergic, glutamatergic, noradrenergic, serotonergic systems, and HPA axis, suggesting that BLT effects expand beyond the circadian pacemaker. AREAS COVERED: In this review, the authors present and discuss recent data of BLT in major depressive disorder, non-seasonal depression, bipolar depression or depressive phase of bipolar disorder, and seasonal affective disorder, as well as in treatment-resistant depression (TRD). The authors further highlight BLT effects in various depressive disorders compared to placebo and report data from several studies suggesting a response to BLT in TRD. Also, the authors report data showing that BLT can be used both as a monotherapy or in combination with other pharmacological treatments. EXPERT OPINION: BLT is an easy-to-use and low-budget therapy with good tolerability. Future studies should focus on clinical and biological predictors of response to BLT, on defining specific populations which may benefit from BLT and establishing treatment protocols regarding timing, frequency, and duration of BLT.

Plasma Brain-Derived Neurotrophic Factor Levels in First-Episode and Recurrent Major Depression and before and after Bright Light Therapy in Treatment-Resistant Depression.

Brain-derived neurotrophic factor (BDNF) is implicated in the etiology and treatment response in major depressive disorder (MDD). However, peripheral BDNF concentrations have not been compared across different MDD stages. Bright light therapy (BLT) offers some potential in treatment-resistant depression (TRD), but its effects on BDNF levels are unknown. This study included a cross-sectional analysis of plasma BDNF concentration in females with TRD, unmedicated MDD patients, and healthy controls (HC), and measurements of longitudinal BLT effects on plasma BDNF levels in TRD patients. The present study included 55 drug-naïve, first-episode patients, 25 drug-free recurrent-episode MDD patients, 71 HC participants, and 54 TRD patients. Patients were rated by Hamilton Depression Rating Scale (HAMD)-17 and the Montgomery-Åsberg Depression Rating Scale (MADRS). Patients with TRD received BLT during 4 weeks. The total HAMD-17 and MADRS scores decreased following BLT. All patient groups had lower plasma BDNF than HC, but BDNF levels did not differ between first- and recurrent-episode BDNF patients and TRD patients before or after BLT. However, responders and remitters to BLT had higher post-treatment plasma BDNF concentrations than patients who did not achieve response or remission. The changes in plasma BDNF levels may be candidates for biomarkers of treatment response to BLT in TRD patients.