Diminished perception of ambient light: a symptom of clinical depression?

Higher amplitudes of visual networks are associated with trait- but not state-depression

Despite depression being a leading cause of global disability, neuroimaging studies have struggled to identify replicable neural correlates of depression or explain limited variance. This challenge may, in part, stem from the intertwined state (current symptoms; variable) and trait (general propensity; stable) experiences of depression.Here, we sought to disentangle state from trait experiences of depression by leveraging a longitudinal cohort and stratifying individuals into four groups: those in remission ('trait depression group'), those with large longitudinal severity changes in depression symptomatology ('state depression group'), and their respective matched control groups (total analytic n = 1030). We hypothesized that spatial network organization would be linked to trait depression due to its temporal stability, whereas functional connectivity between networks would be more sensitive to state-dependent depression symptoms due to its capacity to fluctuate.We identified 15 large-scale probabilistic functional networks from resting-state fMRI data and performed group comparisons on the amplitude, connectivity, and spatial overlap between these networks, using matched control participants as reference. Our findings revealed higher amplitude in visual networks for the trait depression group at the time of remission, in contrast to controls. This observation may suggest altered visual processing in individuals predisposed to developing depression over time. No significant group differences were observed in any other network measures for the trait-control comparison, nor in any measures for the state-control comparison. These results underscore the overlooked contribution of visual networks to the psychopathology of depression and provide evidence for distinct neural correlates between state and trait experiences of depression.

A Population-Based Cohort Study of the Association between Visual Loss and Risk of Suicide and Mental Illness in Taiwan

The psychosocial and health consequences of ocular conditions that cause visual impairment (VI) are extensive and include impaired daily activities, social isolation, cognitive impairment, impaired functional status and functional decline, increased reliance on others, increased risk of motor vehicle accidents, falls and fractures, poor self-rated health, and depression. We aimed to determine whether VI increases the likelihood of a poor prognosis, including mental illness, suicide, and mortality over time. In this large, location, population-based, nested, cohort study, we used data from 2000 to 2015 in the Taiwan National Health Insurance Research Database (NHIRD), which includes diagnoses of all the patients with VI. Baseline features, comorbidities, and prognostic variables were evaluated using a 1:4-matched cohort analysis. Furthermore, comparisons were performed using Cox regression and Bonferroni-correction (for multiple comparisons) to study the association between VI and poor prognosis (mental illness, suicide). The study outcome was the cumulative incidence of poor prognosis among the visually impaired and controls. A two-tailed Bonferroni-corrected p < 0.001 was considered statistically significant. Among the 1,949,101 patients enlisted in the NHIRD, 271 had been diagnosed with VI. Risk factors for poor prognosis and the crude hazard ratio was 3.004 (95% confidence interval 2.135-4.121, p < 0.001). Participants with VI had an increased risk of poor prognosis according to the sensitivity analysis, with a poor prognosis within the first year and first five years. VI was associated with suicide and mental health risks. This study revealed that patients with VI have a nearly 3-fold higher risk of psychiatric disorders, including anxiety, depression, bipolar, and sleep disorders, than the general population. Early detection through comprehensive examinations based on increased awareness in the clinical context may help maintain visual function and avoid additional complications.

Dynamic effects of chronic unpredictable mild stress on the hippocampal transcriptome in rats

Stress causes extensive changes in hippocampal genomic expression, leading to changes in hippocampal structure and function. The dynamic changes in hippocampal gene expression caused by stress of different durations are still unknown. mRNA sequencing was used to analyze the hippocampal transcriptome of rats subjected to chronic unpredictable mild stress (CUMS) of different durations. Compared with the control, 501, 442 and 235 differentially expressed genes (DEGs) were detected in the hippocampus of rats subjected to CUMS for 3 days and 2 and 6 weeks, respectively. Gene Ontology (GO) analysis was used to determine the potential mechanism underlying the dynamic harmful effects of stress on the hippocampus; Certain GO terms of the down‑regulated DEGs in CUMS (3 days) rats were also found in the up‑regulated DEGs in CUMS (6 weeks) rats. These results showed opposing regulation patterns of DEGs between CUMS at 3 days and 6 weeks, which suggested a functional change from adaptation to damage in during the early and late stages of chronic stress. GO analysis for upregulated genes in rats subjected to CUMS for 3 days and 2 weeks suggested significant changes in 'extracellular matrix' and 'wound healing'. Upregulated genes in rats subjected to CUMS for 2 weeks were involved in changes associated with visual function. GO analysis of DEGs in rats subjected to CUMS for 6 weeks revealed increased expression of genes associated with 'apoptotic process' and 'aging' and decreased expression of those associated with inhibition of cell proliferation and cell structure. These results suggest that the early and middle stages of chronic stress primarily promote adaptive regulation and damage repair in the organism, while the late stage of chronic stress leads to damage in the hippocampus.

Gender differences in major depressive disorders: A resting state fMRI study

BACKGROUND

Major depressive disorder (MDD) has a high disability rate and brings a large disease burden to patients and the country. Significant sex differences exist in both the epidemiological and clinical features in MDD. The effect of sex on brain function in MDD is not clear now. Regional homogeneity (ReHo) and ALFF are widely used research method in the study of brain function. This research aimed to use ReHo and ALFF to explore gender differences in brain function images in MDD.

METHODS

Eighty first-episode drug-naive patients (47 women and 30 men) with MDD and 85 age, education matched healthy volunteers (47 women and 31 men) were recruited in our study and participated in resting-state functional magnetic resonance imaging scans. ReHo and ALFF were used to assess brain activity, two-way ANOVA and post hoc analysis was conducted to explore the sex difference in MDD. Correlation analysis was used to explore the relationship between abnormal brain functioning and clinical symptoms.

RESULTS

We observed sex-specific patterns and diagnostic differences in MDD Patients, further post hoc comparisons indicated that women with MDD showed decreased ALFF value in the right superior occipital gyrus and decreased ReHo value in the left calcarine and left dorsolateral superior frontal gyrus compared with HC females and men with MDD. Men with MDD showed decreased ReHo value in the right median cingulate gyrus compared with HC males and increased ReHo value in the left dorsolateral superior frontal gyrus compared with HC males, we also found that HC males showed higher ReHo value in the right median cingulate gyrus than HC females.

CONCLUSIONS

Men and women do have sex differences in brain function, the occipital lobe, calcarine, DLPFC, and DCG were the main different brain regions found between male and female in MDD, which may be the biomarker brain regions that can help diagnose and treat MDD in men and women.

Potential of Antithrombin III as a Biomarker of Antidepressive Effect in Major Depressive Disorder

Background: The evaluation of treatment response to antidepressant therapy commonly depends on neuropsychologic assessments, as there are currently no suitable biomarkers. Previous research has identified a panel of increased proteins in patients with major depressive disorder (MDD), including antithrombin III (ATIII), as potential biomarkers of depression. Methods: A total of 90 MDD patients were recruited. Of these, 74 patients received occipital repetitive transcranial magnetic stimulation (rTMS) as individualized, standard, or sham treatment for 5 days, and underwent the complete procedure, including clinical assessments, blood collection, and protein measurement. Results: After treatment, ATIII was significantly decreased in both the individualized and standard groups (both p < 0.001) relative to the sham group. In the individualized group, reduction in ATIII was associated with improvements in several neuropsychological assessments. Furthermore, ATIII at baseline in the standard group and after individualized rTMS showed good performance for evaluating or predicting the response to five-day treatment (AUC = 0.771, 95% CI, 0.571-0.971; AUC = 0.875, 95% CI, 0.714-1.000, respectively) and remission at follow-up (AUC = 0.736, 95% CI, 0.529-0.943; AUC = 0.828, 95% CI, 0.656-1.000, respectively). Lastly, both baseline ATIII and change in ATIII showed good predictive value for the 24-item Hamilton Depression Rating Scale at follow-up (p = 0.024 and 0.023, respectively). Conclusion: Our study revealed a reduction in ATIII after occipital rTMS in MDD patients and a relationship between change in ATIII and therapeutic response. Taken together, these findings provide evidence for the potential of ATIII as a biomarker for the evaluation and prediction of antidepressive effects.

Psychological contribution to understanding the nature of dry eye disease: a cross-sectional study of anxiety sensitivity and dry eyes

Dry eye disease (DED) represents a common health problem in the general population. Previous studies have demonstrated that the subjective symptoms of dry eye are associated with several psychological factors, including depression, anxiety and post-traumatic stress disorder. However, there is a lack of empirical information about the mechanisms underlying the relationships between DED and various psychological symptoms. In light of emerging evidence of its trans-diagnostic nature, anxiety sensitivity (i.e. AS) represents one promising factor for further understanding DED. The present study aimed to explore whether anxiety sensitivity plays a role in the perception of DED symptoms in a community-based sample of adults aged 20-89 years (N = 381; M = 39.72, SD = 12.6). A dry ocular surface was reported by 22.8% of the participants. As expected, women more often reported symptoms of dry eye that could be categorized as moderate to severe. The findings demonstrated that AS, and the AS-psychological concerns dimension in particular, predict the intensity of dry eye symptoms above and beyond depressive and anxiety symptoms. These findings add to a growing body of work underscoring the relevance of AS in increasing the risk of chronic medical conditions.

People with current major depression resemble healthy controls on flash Electroretinogram indices associated with impairment in people with stabilized schizophrenia

Flash electroretinography (fERG) has been used to identify anomalies in retinal functioning in several psychiatric disorders. In schizophrenia (SCZ), fERG abnormalities are reliably observed, but findings from studies of major depressive disorder (MDD) have been less consistent. In this study, fERG data were recorded from MDD patients in a current major depressive episode (n = 25), and compared to data from SCZ patients (n = 25) and healthy controls (HC; n = 25), to determine the degree to which fERG anomalies in acute MDD overlap or contrast with those observed in stabilized (though not symptom free) SCZ. The primary variables of interest were a-wave (photoreceptor activity), b-wave (bipolar-Müller cell activity), and photopic negative response (PhNR; ganglion cell activity) amplitudes and implicit times. Across most conditions, there were no significant differences between the MDD and HC groups in a- or b-wave response, but the SCZ group consistently demonstrated reduced amplitudes. Interestingly, MDD patients demonstrated an increase in photopic a-wave implicit time relative to SCZ patients, and a decrease in PhNR implicit time relative to controls. Correlations between BDI-II scores and fERG metrics were not significant for either patient group. Overall, these data indicate that, using an fERG protocol that distinguishes SCZ patients from controls, MDD patients experiencing a current depressive episode closely resemble healthy controls in their fERG responses. Therefore, MDD-related fERG changes may be more subtle than those observed in SCZ and detectable only with larger sample sizes than we employed and/or using a different set of fERG test parameters.

High level of pattern glare in major depressive disorder

BACKGROUND

Visual deficits have been reported in abundance by recent studies on major depressive disorder. Pattern glare manifests as visual distortions, such as the symptoms of headache, glare, eyestrain, illusions of shapes, colors, and motion when viewing repetitive striped patterns, of which some can be observed in major depressive disorder. Inspired by what mentioned, the present study aims to explore whether there exists association between pattern glare and major depressive disorder and further attempts to explore possible clinical diagnostic value of pattern glare in major depressive disorder.

METHODS

Twenty-four patients diagnosed with major depressive disorder (MDDs group) were compared with 30 age-, gender- and education level-matched healthy control subjects (HCs group) on their visual stress with black-and-white gratings of different spatial frequencies-0.3 (low-SF), 2.3 (mid-SF), and 9.4 (high-SF) cycles per degree (c/deg)-which was named pattern glare test. The MDDs group divided into first episode medication-free group (fMDD) and recurrent medicated group (rMDD), comparisons of pattern glare scores (PGS) were performed within the MDDs group. We used Pearson and Spearman analysis to explore the relationship between some clinical indexes and pattern glare scores. ROC (receiver operating characteristic) curve was used to evaluate whether pattern glare test was able to discriminate patients and healthy controls.

RESULTS

The mid-SF pattern glare score significantly elevated in patients with major depressive disorder compared to control subjects. No differences of pattern glare scores were found between fMDD and rMDD. A significant negative correlation between mid-high difference and age in HCs group was found. There were no correlations between other variables and pattern glare scores. The mid-SF score has limited value in the diagnosis of major depressive disorder.

CONCLUSIONS

We observed an increased level of pattern glare in patients with major depressive disorder, reflecting the existence of cortical hyper-excitability in major depressive disorder. The mid-SF score may have a value in understanding cortical excitability in major depressive disorder.

Depression Prediction by Using Ecological Momentary Assessment, Actiwatch Data, and Machine Learning: Observational Study on Older Adults Living Alone

BACKGROUND

Although geriatric depression is prevalent, diagnosis using self-reporting instruments has limitations when measuring the depressed mood of older adults in a community setting. Ecological momentary assessment (EMA) by using wearable devices could be used to collect data to classify older adults into depression groups.

OBJECTIVE

The objective of this study was to develop a machine learning algorithm to predict the classification of depression groups among older adults living alone. We focused on utilizing diverse data collected through a survey, an Actiwatch, and an EMA report related to depression.

METHODS

The prediction model using machine learning was developed in 4 steps: (1) data collection, (2) data processing and representation, (3) data modeling (feature engineering and selection), and (4) training and validation to test the prediction model. Older adults (N=47), living alone in community settings, completed an EMA to report depressed moods 4 times a day for 2 weeks between May 2017 and January 2018. Participants wore an Actiwatch that measured their activity and ambient light exposure every 30 seconds for 2 weeks. At baseline and the end of the 2-week observation, depressive symptoms were assessed using the Korean versions of the Short Geriatric Depression Scale (SGDS-K) and the Hamilton Depression Rating Scale (K-HDRS). Conventional classification based on binary logistic regression was built and compared with 4 machine learning models (the logit, decision tree, boosted trees, and random forest models).

RESULTS

On the basis of the SGDS-K and K-HDRS, 38% (18/47) of the participants were classified into the probable depression group. They reported significantly lower scores of normal mood and physical activity and higher levels of white and red, green, and blue (RGB) light exposures at different degrees of various 4-hour time frames (all P<.05). Sleep efficiency was chosen for modeling through feature selection. Comparing diverse combinations of the selected variables, daily mean EMA score, daily mean activity level, white and RGB light at 4:00 pm to 8:00 pm exposure, and daily sleep efficiency were selected for modeling. Conventional classification based on binary logistic regression had a good model fit (accuracy: 0.705; precision: 0.770; specificity: 0.859; and area under receiver operating characteristic curve or AUC: 0.754). Among the 4 machine learning models, the logit model had the best fit compared with the others (accuracy: 0.910; precision: 0.929; specificity: 0.940; and AUC: 0.960).

CONCLUSIONS

This study provides preliminary evidence for developing a machine learning program to predict the classification of depression groups in older adults living alone. Clinicians should consider using this method to identify underdiagnosed subgroups and monitor daily progression regarding treatment or therapeutic intervention in the community setting. Furthermore, more efforts are needed for researchers and clinicians to diversify data collection methods by using a survey, EMA, and a sensor.

Altered white matter microstructure in patients with post-stroke depression detected by diffusion kurtosis imaging

The aim of our study is to determine the pathological changes of white matter microstructure in patients with early post-stroke depression (PSD), and to investigate the association between white matter integrity examined by diffusion kurtosis imaging (DKI) and early PSD. Thirty-eight patients with acute cerebral infarction were selected, including 17 patients with depression (PSD group), and 21 patients without depression (N-PSD group). In addition, 20 normal healthy controls (NORM group) were selected. All were taken DKI scans. The white matter of the frontal lobe, temporal lobe, parietal lobe, occipital lobe, anterior limb of internal capsule, and posterior limb of internal capsule, in addition to the genu of corpus callosum and splenium of corpus callosum was selected as a region of interest (ROI). Selected parameters include fractional anisotropy (FA) and mean kurtosis (MK). Compared with N-PSD group and NORM group, FA value of the left frontal lobe and MK value of the bilateral frontal lobe, bilateral temporal lobe, and genu of corpus callosum in PSD group were decreased (P < 0.05). Our results indicated that the early PSD patients had white matter microstructure abnormalities in the frontal lobe, temporal lobe, and genu of corpus callosum. DKI provides a comprehensive brain imaging reference for detecting early microstructural damage of white matter in PSD patients, which can be used as an imaging biomarker to detect early PSD and its progression potentially.

Decreased daytime illumination leads to anxiety-like behaviors and HPA axis dysregulation in the diurnal grass rat (Arvicanthis niloticus)

The impact of ambient light on mood and anxiety is best exemplified in seasonal affective disorder, in which patients experience depression and anxiety in winter when there is less light in the environment. However, the brain mechanisms underlying light-dependent changes in affective state remain unclear. Our previous work revealed increased depression-like behaviors in the diurnal Nile grass rat (Arvicanthis niloticus) housed in a dim light-dark (dim-LD) cycle as compared to the controls housed in a bright light-dark (bright-LD) condition. As depression is often comorbid with anxiety and is associated with dysregulation of the body's stress response system, the present study examined the anxiety-like behaviors as well as indicators of the hypothalamic-pituitary-adrenal (HPA) axis functioning in the grass rats. Animals housed in dim-LD showed increased anxiety-like behaviors compared to bright-LD controls, as revealed by fewer entries and less time spent at the center in the open field test and more marbles buried during the marble-burying test. Following the marble-burying test, dim-LD animals showed higher plasma corticosterone (CORT) levels and hippocampal Fos expression. Although the daily CORT rhythm was comparable between bright-LD and dim-LD groups, the day/night variation of corticotropin-releasing hormone mRNA expression in the paraventricular nucleus was diminished in dim-LD animals. In addition, glucocorticoid receptor and mineralocorticoid receptor mRNA expression were higher in the hippocampus of dim-LD animals. The results suggest that in diurnal species, reduced daytime illumination can lead to increased anxiety-like behaviors and altered HPA axis functioning, providing insights into the link between decreased environmental illumination and negative emotion.

Colour fluctuations in grapheme-colour synaesthesia: The effect of clinical and non-clinical mood changes

Synaesthesia is a condition that gives rise to unusual secondary sensations (e.g., colours are perceived when listening to music). These unusual sensations tend to be reported as being stable throughout adulthood (e.g., Simner & Logie, 2007, Neurocase, 13, 358) and the consistency of these experiences over time is taken as the behavioural hallmark of genuineness. Our study looked at the influence of mood states on synaesthetic colours. In Experiment 1, we recruited grapheme-colour synaesthetes (who experience colours from letters/digits) and elicited their synaesthetic colours, as well as their mood and depression states, in two different testing sessions. In each session, participants completed the PANAS-X (Watson & Clark, 1999) and the BDI-II (Beck, Steer, & Brown, 1996, Manual for Beck Depression Inventory-II), and chose their synaesthetic colours for letters A-Z from an interactive colour palette. We found that negative mood significantly decreased the luminance of synaesthetic colours. In Experiment 2, we showed that synaesthetic colours were also less luminant for synaesthetes with anxiety disorder, versus those without. Additional evidence suggests that colour saturation, too, may inversely correlate with depressive symptoms. These results show that fluctuations in mood within both a normal and clinical range influence synaesthetic colours over time. This has implications for our understanding about the longitudinal stability of synaesthetic experiences, and of how mood may interact with the visual (imagery) systems.

Vision in depressive disorder

BACKGROUND

Reduced dopaminergic transmission has been implicated in the pathophysiology of major depression. Furthermore, dopaminergic neurotransmission plays an important role in the physiology of visual contrast sensitivity (CS). To test the hypothesis that altered dopaminergic neurotransmission plays a role in major depression we measured contrast sensitivity in patients with major depression and in healthy control subjects.

METHODS

Twenty-eight patients diagnosed with major depressive disorder were compared to 21 age-matched control subjects on their ability to detect a Gabor target with slightly elevated luminance contrast embedded in seven equi-contrast distracters.

RESULTS

Contrast discrimination thresholds were significantly elevated in unmedicated and medicated patients with major depression compared to control subjects, at all pedestal contrast levels tested.

CONCLUSIONS

Contrast discrimination performance is reduced in depressive patients and might reflect a state of altered dopaminergic neurotransmission.

Reduced density of calbindin immunoreactive GABAergic neurons in the occipital cortex in major depression: relevance to neuroimaging studies

BACKGROUND

Several lines of evidence suggest dysfunction of the gamma-aminobutyric acid (GABA)ergic system in major depressive disorder. Neuroimaging studies report reduced levels of GABA in the dorsolateral prefrontal and occipital cortex of depressed patients. Our previous postmortem study revealed a reduction in the density and size of calbindin-immunoreactive (CB-IR) GABAergic neurons in the prefrontal cortex in major depressive disorder. The goal of this study was to test whether the changes in CB-IR neurons can also be detected in the occipital cortex, where neuroimaging studies report a prominent GABA decrease.

METHODS

A three-dimensional cell counting probe was used to assess the cell-packing density and size of CB-IR neurons in layer II of the occipital cortex in 10 major depressive disorder subjects and 10 psychiatrically healthy control subjects.

RESULTS

The density of CB-IR neurons was significantly decreased by 28% in major depressive disorder subjects compared with the control group. The size of CB-IR neurons was unchanged in major depressive disorder subjects when compared with control subjects.

CONCLUSIONS

The reduction in the density of CB-IR GABAergic neurons in the occipital cortex in depression is similar to that observed previously in the prefrontal cortex. Deficit in cortical GABAergic interneurons may contribute to the low GABA levels detected in neuroimaging studies in major depressive disorder patients.

Diminished perception of light as a symptom of depression: further studies

BACKGROUND

In a previous preliminary report, the perception of a decrease in ambient light intensity appeared to be correlated with depression. We prospectively studied this potential link in a controlled study.

METHODS

The question, "I've noticed that the lights in my surroundings seem dimmer than usual", was added to the Center for Epidemiologic Studies Depression Scale (CES-D) questionnaire and administered prospectively to 213 subjects 50-80 years of age participating in the Age-Related Eye Disease Study (AREDS). All had visual acuity of 20/32 or better in at least one eye. Main outcome measures were the relationship between the dimness question answer and severity of depression, and the likelihood that patients reporting dimness were depressed.

RESULTS

Subjects endorsing their surroundings as being dimmer than usual at least some of the time had a mean CES-D score of 10.6 (SD=7.0) compared to a mean of 5.5 (SD=5.4) for subjects who never noted dimness (t=-4.22, p=.0001). Depressed individuals (CES-D > or = 16) were significantly more likely to report dimness than non-depressed (CES-D<16) subjects (chi(2)=15.6, p<0.0001). The total CES-D score and the degree of reported dimness (0-3) were significantly associated (r=0.31, p<.0001). Using a stepwise regression analysis, subjects who reported any dimness were more likely to be depressed.

LIMITATIONS

A relatively small number of subjects, 38 (18%), reported dimness requiring us to dichotomize their dimness level in some analyses.

CONCLUSIONS

Perceived dimness of one's ambient surroundings and clinical depression are linked. Health care professionals should inquire about this symptom in potentially depressed patients.

Illuminating the impact of habitual behaviors in depression

Researchers have hypothesized that habitual behaviors are zeitgebers for the circadian clock. However, few studies have examined the relationship between habitual behaviors and light, the strongest zeitgeber. Depression is an ideal model in which to explore this relationship because depression is a disorder associated with disruptions in circadian biological activity, sleep, and social rhythms (or patterns of habitual behaviors). We hypothesized that individuals with fewer habitual behaviors have less average exposure to light from morning rise time to evening bedtime and that a reduction in light exposure increases the likelihood of depression. Thirty-nine depressed and 39 never-depressed participants wore an ambulatory light monitor and completed the Social Rhythm Metric over the course of 2 weeks. Linear and logistic regression techniques were used to calculate regression coefficients, and confidence limits based on the distribution of the product of two normal random variables were computed to test the significance of the mediation effect. Infrequent habitual behaviors were associated with a decrease in average levels of light exposure, and low levels of light increased the likelihood of depression. This mediation effect was partial; the overall number of habitual behaviors had a direct relationship with depression above and beyond the association with light exposure. Longitudinal studies are needed to empirically demonstrate the direction of relationships between each of the variables tested.

Sleep responses to light and dark are shaped by early experience

Light regulates sleep timing through circadian entrapment and by eliciting acute changes in behavior. These behaviors are mediated by the subcortical visual system, retinorecipient nuclei distinct from the geniculocortical system. To test the hypothesis that early visual experience shapes light regulation of behavior, the authors recorded sleep in albino rats reared in continuous dark, continuous light, or a 12-hr light-dark cycle. Dark rearing strengthened and light rearing weakened acute responses to light, including light modulation of REM sleep, a marker for pretectal function in albino rats. However, neither dark nor light rearing altered daily amounts of wakefulness, non-REM sleep, or REM sleep. Thus, light and dark rearing might differentially affect the balance between acute and circadian responses to light that, in concert, govern sleep timing.