Pupillary motility responses to affectively salient stimuli in individuals with depression or elevated risk of depression: A systematic review and meta-analysis.

Elaborative affective processing is observed in depression, and pupillary reactivity, a continuous, sensitive, and reliable indicator of physiological arousal and neurocognitive processing, is increasingly utilized in studies of depression-related characteristics. As a first attempt to quantitively summarize existing evidence on depression-related pupillary reactivity alterations, this review and meta-analysis evaluated the direction, magnitude, and specificity of pupillary indices of affective processing towards positively, negatively, and neutrally-valenced stimuli among individuals diagnosed with depression or with elevated risk of depression. Studies on pupillary responses to affective stimuli in the target groups were identified in PsycINFO and PubMed databases. Twenty-two articles met inclusion criteria for the qualitative review and 16 for the quantitative review. Three-level frequentist and Bayesian models were applied to summarize pooled effects from baseline-controlled stimuli-induced average changes in pupillary responses. In general, compared to non-depressed individuals, individuals with depression or elevated risk of depression exhibited higher pupillary reactivity (d =0.15) towards negatively-valenced stimuli during affective processing. Pupillary motility towards negatively-valenced stimuli may be a promising trait-like marker for depression vulnerability.

Brain structure and parasympathetic function during rest and stress in young adult women.

Heart rate variability (HRV) is an important biomarker for parasympathetic function and future health outcomes. The present study examined how the structure of regions in a neural network thought to maintain top-down control of parasympathetic function is associated with HRV during both rest and social stress. Participants were 127 young women (90 Black American), who completed a structural MRI scan and the Trier Social Stress Test (TSST), during which heart rate was recorded. Regression analyses were used to evaluate associations between cortical thickness in five regions of the Central Autonomic Network (CAN; anterior midcingulate cortex [aMCC], pregenual and subgenual anterior cingulate cortex [pgACC, sgACC], orbitofrontal cortex [OFC], and anterior insula) and high-frequency HRV during rest and stress. Results indicated that cortical thickness in CAN regions did not predict average HRV during rest or stress. Greater cortical thickness in the right pgACC was associated with greater peak HRV reactivity during the TSST, and survived correction for multiple comparisons, but not sensitivity analyses with outliers removed. The positive association between cortical thickness in the pgACC and peak HRV reactivity is consistent with the direction of previous findings from studies that examined tonic HRV in adolescents, but inconsistent with findings in adults, which suggests a possible neurodevelopmental shift in the relation between brain structure and autonomic function with age. Future research on age-related changes in brain structure and autonomic function would allow a more thorough understanding of how brain structure may contribute to parasympathetic function across neurodevelopment.

Gray matter volume and executive functioning correlate with time since injury following mild traumatic brain injury.

Most people who sustain a mild traumatic brain injury (mTBI) will recover to baseline functioning within a period of several days to weeks. A substantial minority of patients, however, will show persistent symptoms and mild cognitive complaints for much longer. To more clearly delineate how the duration of time since injury (TSI) is associated with neuroplastic cortical volume changes and cognitive recovery, we employed voxel-based morphometry (VBM) and select neuropsychological measures in a cross-sectional sample of 26 patients with mTBI assessed at either two-weeks, one-month, three-months, six-months, or one-year post injury, and a sample of 12 healthy controls. Longer duration of TSI was associated with larger gray matter volume (GMV) within the ventromedial prefrontal cortex (vmPFC) and right fusiform gyrus, and better neurocognitive performance on measures of visuospatial design fluency and emotional functioning. In particular, volume within the vmPFC was positively correlated with design fluency and negatively correlated with symptoms of anxiety, whereas GMV of the fusiform gyrus was associated with greater design fluency and sustained visual psychomotor vigilance performance. Moreover, the larger GMV seen among the more chronic individuals was significantly greater than healthy controls, suggesting possible enlargement of these regions with time since injury. These findings are interpreted in light of burgeoning evidence suggesting that cortical regions often exhibit structural changes following experience or practice, and suggest that with greater time since an mTBI, the brain displays compensatory remodeling of cortical regions involved in emotional regulation, which may reduce distractibility during attention demanding visuo-motor tasks.

Exposure to Blue Light Increases Subsequent Functional Activation of the Prefrontal Cortex During Performance of a Working Memory Task.

STUDY OBJECTIVES: Prolonged exposure to blue wavelength light has been shown to have an alerting effect, and enhances performance on cognitive tasks. A small number of studies have also shown that relatively short exposure to blue light leads to changes in functional brain responses during the period of exposure. The extent to which blue light continues to affect brain functioning during a cognitively challenging task after cessation of longer periods of exposure (i.e., roughly 30 minutes or longer), however, has not been fully investigated. METHODS: A total of 35 healthy participants (18 female) were exposed to either blue (469 nm) (n = 17) or amber (578 nm) (n = 18) wavelength light for 30 minutes in a darkened room, followed immediately by functional magnetic resonance imaging (fMRI) while undergoing a working memory task (N-back task). RESULTS: Participants in the blue light condition were faster in their responses on the N-back task and showed increased activation in the dorsolateral (DLPFC) and ventrolateral (VLPFC) prefrontal cortex compared to those in the amber control light condition. Furthermore, greater activation within the VLPFC was correlated with faster N-back response times. CONCLUSIONS: This is the first study to suggest that a relatively brief, single exposure to blue light has a subsequent beneficial effect on working memory performance, even after cessation of exposure, and leads to temporarily persisting functional brain changes within prefrontal brain regions associated with executive functions. These findings may have broader implication for using blue-enriched light in a variety of work settings where alertness and quick decision-making are important.

Whole-Body Hyperthermia for the Treatment of Major Depressive Disorder: A Randomized Clinical Trial.

IMPORTANCE: Limitations of current antidepressants highlight the need to identify novel treatments for major depressive disorder. A prior open trial found that a single session of whole-body hyperthermia (WBH) reduced depressive symptoms; however, the lack of a placebo control raises the possibility that the observed antidepressant effects resulted not from hyperthermia per se, but from nonspecific aspects of the intervention. OBJECTIVE: To test whether WBH has specific antidepressant effects when compared with a sham condition and to evaluate the persistence of the antidepressant effects of a single treatment. DESIGN, SETTING, AND PARTICIPANTS: A 6-week, randomized, double-blind study conducted between February 2013 and May 2015 at a university-based medical center comparing WBH with a sham condition. All research staff conducting screening and outcome procedures were blinded to randomization status. Of 338 individuals screened, 34 were randomized, 30 received a study intervention, and 29 provided at least 1 postintervention assessment and were included in a modified intent-to-treat efficacy analysis. Participants were medically healthy, aged 18 to 65 years, met criteria for major depressive disorder, were free of psychotropic medication use, and had a baseline 17-item Hamilton Depression Rating Scale score of 16 or greater. INTERVENTIONS: A single session of active WBH vs a sham condition matched for length of WBH that mimicked all aspects of WBH except intense heat. MAIN OUTCOMES AND MEASURES: Between-group differences in postintervention Hamilton Depression Rating Scale scores. RESULTS: The mean (SD) age was 36.7 (15.2) years in the WBH group and 41.47 (12.54) years in the sham group. Immediately following the intervention, 10 participants (71.4%) randomized to sham treatment believed they had received WBH compared with 15 (93.8%) randomized to WBH. When compared with the sham group, the active WBH group showed significantly reduced Hamilton Depression Rating Scale scores across the 6-week postintervention study period (WBH vs sham; week 1: -6.53, 95% CI, -9.90 to -3.16, P < .001; week 2: -6.35, 95% CI, -9.95 to -2.74, P = .001; week 4: -4.50, 95% CI, -8.17 to -0.84, P = .02; and week 6: -4.27, 95% CI, -7.94 to -0.61, P = .02). These outcomes remained significant after evaluating potential moderating effects of between-group differences in baseline expectancy scores. Adverse events in both groups were generally mild. CONCLUSIONS AND RELEVANCE: Whole-body hyperthermia holds promise as a safe, rapid-acting, antidepressant modality with a prolonged therapeutic benefit. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01625546.

Daytime sleepiness is associated with altered resting thalamocortical connectivity.

Thalamocortical connectivity is believed to underlie basic alertness, motor, sensory information processing, and attention processes. This connectivity appears to be disrupted by total sleep deprivation, but it is not known whether it is affected by normal variations in general daytime sleepiness in nonsleep deprived persons. Healthy adult participants completed the Epworth Sleepiness Scale and underwent resting-state functional MRI. Functional connectivity between the thalamus and other regions of the cortex was examined and correlated with Epworth Sleepiness Scale scores. Greater sleepiness was associated with inverse (i.e. lower or more negative) connectivity between the bilateral thalamus and cortical regions involved in somatosensory and motor functions, potentially reflecting the disengagement of sensory and motor processing from the stream of consciousness.