Photobiomodulation for Major Depressive Disorder: Linking Transcranial Infrared Light, Biophotons and Oxidative Stress.

ABSTRACT: Incompletely treated major depressive disorder (MDD) poses an enormous global health burden. Conventional treatment for MDD consists of pharmacotherapy and psychotherapy, though a significant number of patients do not achieve remission with such treatments. Transcranial photobiomodulation (t-PBM) is a promising novel therapy that uses extracranial light, especially in the near-infrared (NIR) and red spectra, for biological and therapeutic effects. The aims of this Review are to evaluate the current clinical and preclinical literature on t-PBM in MDD and to discuss candidate mechanisms for effects of t-PBM in MDD, with specific attention to biophotons and oxidative stress. A search on PubMed and ClinicalTrials.gov identified clinical and preclinical studies using t-PBM for the treatment of MDD as a primary focus. After a systematic screening, only 19 studies containing original data were included in this review (9 clinical and 10 preclinical trials). Study results demonstrate consensus that t-PBM is a safe and potentially effective treatment; however, varying treatment parameters among studies complicate definitive conclusions about efficacy. Among other mechanisms of action, t-PBM stimulates the complex IV of the mitochondrial respiratory chain and induces an increase in cellular energy metabolism. We suggest that future trials include biological measures to better understand the mechanisms of action of t-PBM and to optimize treatment efficiency. Of particular interest going forward will be studying potential effects of t-PBM-an external light source on the NIR spectra-on neural circuitry implicated in depression.

Identifying pathways between psychiatric symptoms and psychosocial functioning in the general population.

The present study aims to identify pathways between psychiatric network symptoms and psychosocial functioning and their associated variables among functioning clusters in the general population. A cross-sectional web-based survey was administered in a total of 3,023 individuals in Brazil. The functioning clusters were derived by a previous study identifying three different groups based on the online Functioning Assessment Short Test. Networking analysis was fitted with all items of the Patient-Reported Outcomes Measurement Information System for depression and for anxiety (PROMIS) using the mixed graphical model. A decision tree model was used to identify the demographic and clinical characteristics of good and low functioning. A total of 926 (30.63%) subjects showed good functioning, 1,436 (47.50%) participants intermediate functioning, and 661 (21.86%) individuals low functioning. Anxiety and uneasy symptoms were the most important nodes for good and intermediate clusters but anxiety, feeling of failure, and depression were the most relevant symptoms for low functioning. The decision tree model was applied to identify variables capable to discriminate individuals with good and low functioning. The algorithm achieved balanced accuracy 0.75, sensitivity 0.87, specificity 0.63, positive predictive value 0.63 negative predictive value 0.87 (p<0.001), and an area under the curve of 0.83 (95%CI:0.79-0.86, p<0.01). Our results show that individuals who present psychological distress are more likely to experience poor functional status, suggesting that this subgroup should receive a more comprehensive psychiatric assessment and mental health care.

Clinical differences between melancholic and nonmelancholic depression as defined by the CORE system.

BACKGROUND: The definition and delineation of melancholia have remained elusive for an extended period. A longstanding signal of psychomotor disturbance has been operationalized via the observer-rated CORE measure and with CORE-assigned melancholic and nonmelancholic compared in several Australian studies. Replication studies in other regions have not previously been reported. This study compares Brazilian patients with melancholic and nonmelancholic depression according to the CORE measure of psychomotor disturbance in terms of clinical characteristics, suicide ideation, stressful life events, quality of life, parental care, and personality styles. METHODS: A total of 181 patients with unipolar major depression attending a tertiary care outpatient service in Brazil were evaluated in relation to melancholic status and study variables. RESULTS: The CORE-assigned melancholic patients presented higher symptom severity, greater prevalence of suicide ideation, and Axis I comorbidities than nonmelancholics. Scores of dysfunctional personality styles and dysfunctional parental care measures were also higher among melancholics. Quality-of-life scores were low in both groups. LIMITATIONS: The absence of a criterion standard for the diagnosis of melancholia and the use of medication can be potential limitations of the study. CONCLUSION: Differences suggest that CORE-assigned melancholia defines a distinct group of patients and probably a disorder distinct from nonmelancholic depression not only in quantitative but also in qualitative aspects.

Contextual recognition memory deficits in major depression are suppressed by cognitive support at encoding.

OBJECTIVES: To investigate the effect of cognitive support (an associative orienting instruction at encoding) on contextual memory in depressed patients. METHODS: Seventeen patients (age 20-40 years, 14 women) diagnosed with major depressive disorder (MDD) and 22 healthy controls matched for age, gender and education completed a recognition memory task for item (object) and context (location), with or without an incidental binding cue at encoding. In addition, participants completed the vocabulary subtest of the Wechsler Adult Intelligence Scale (WAIS III) and the Wisconsin Card Sorting Test (WCST). Salivary samples were collected at 7 AM, 4 PM and 10 PM on the day of testing for cortisol and DHEA level measurement. RESULTS: Depressed patients showed a deficit in contextual memory in the absence of a binding cue but did not differ from healthy controls in item memory or when a binding cue was present. Cortisol and cortisol/DHEA ratios were lower in depressed patients compared to healthy controls and correlated with memory deficits. CONCLUSIONS: Contextual memory deficits in MDD patients can be reduced by providing cognitive support at encoding.