SAD rats: Effects of short photoperiod and carbohydrate consumption on sleep, liver steatosis, and the gut microbiome in diurnal grass rats

Seasonal affective disorder (SAD) is a recurrent depression triggered by exposure to short photoperiods, with a subset of patients reporting hypersomnia, increased appetite, and carbohydrate craving. Dysfunction of the microbiota - gut - brain axis is frequently associated with depressive disorders, but its role in SAD is unknown. Nile grass rats (Arvicanthis niloticus) are potentially useful for exploring the pathophysiology of SAD, as they are diurnal and have been found to exhibit anhedonia and affective-like behavior in response to short photoperiods. Further, given grass rats have been found to spontaneously develop metabolic syndrome, they may be particularly susceptible to environmental triggers of metabolic dysbiosis. We conducted a 2 × 2 factorial design experiment to test the effects of short photoperiod (4 h:20 h Light:Dark (LD) vs. neutral 12:12 LD), access to a high concentration (8%) sucrose solution, and the interaction between the two, on activity, sleep, liver steatosis, and the gut microbiome of grass rats. We found that animals on short photoperiods maintained robust diel rhythms and similar subjective day lengths as controls in neutral photoperiods but showed disrupted activity and sleep patterns (i.e. a return to sleep after an initial bout of activity that occurs ~ 13 h before lights off). We found no evidence that photoperiod influenced sucrose consumption. By the end of the experiment, some grass rats were overweight and exhibited signs of non-alcoholic fatty liver disease (NAFLD) with micro- and macro-steatosis. However, neither photoperiod nor access to sucrose solution significantly affected the degree of liver steatosis. The gut microbiome of grass rats varied substantially among individuals, but most variation was attributable to parental effects and the microbiome was unaffected by photoperiod or access to sucrose. Our study indicates short photoperiod leads to disrupted activity and sleep in grass rats but does not impact sucrose consumption or exacerbate metabolic dysbiosis and NAFLD.

Orphan nuclear receptor nr4a1 regulates winter depression-like behavior in medaka

About 10% of the population suffers from depression in winter at high latitude. Although it has become a serious public health issue, its underlying mechanism remains unknown and new treatments and therapies are required. As an adaptive strategy, many animals also exhibit depression-like behavior in winter. Previously, it has been reported that celastrol, a traditional Chinese medicine, can rescue winter depression-like behavior in medaka, an excellent model of winter depression. Nuclear receptor subfamily 4 group A member 1 (nr4a1, also known as nur77) is a known target of celastrol, and the signaling pathway of nr4a1 was suggested to be inactive in medaka brain during winter, implying the association of nr4a1 and winter depression-like behavior. However, the direct evidence for its involvement in winter depression-like behavior remains unclear. The present study found that nr4a1 was suppressed in the medaka brain under winter conditions. Cytosporone B, nr4a1 chemical activator, reversed winter depression-like behavior under winter conditions. Additionally, nr4a1 mutant fish generated by CRISPR/Cas9 system showed decreased sociability under summer conditions. Therefore, our results demonstrate that the seasonal regulation of nr4a1 regulates winter depression-like behavior and offers potential therapeutic target.

Diet and depression: A systematic review of whole dietary interventions as treatment in patients with depression

BACKGROUND & RATIONALE

Depression is a common mental illness that afflicts over 300 million individuals worldwide. Despite a variety of therapeutic options available, a significant number of depressed patients fail to respond to treatment. Current guidelines for treating depression suggest that supplementation of essential nutrients may be an appropriate adjunctive to treatment, but research investigating full dietary interventions for depressed patients is scarce.

STUDY OBJECTIVE

The primary aim of this study was to systematically review published scientific literature investigating full dietary interventions as treatment for individuals with a diagnosis of depression. In doing so, we assessed existing evidence for recommendation of a dietary intervention and reviewed theory of how diet may be important in this context.

METHODS

A systematic search was conducted using OVID to search Medline, PsychINFO, and EMBASE, and PubMed for relevant publications. Only studies including full dietary interventions for patients with Major Depressive Episode, Major Depressive Disorder, Persistent Depressive Disorder, Seasonal Affective Disorder, or Dysthymia, as diagnosed using criteria defined in the chapter of "Depressive Disorders" in the DSM, were included.

RESULTS

Only five studies met the inclusion criteria for this review. All five studies included in this review reported improvements in mood following dietary intervention as compared to the comparison group. However, heterogeneity in both the dietary intervention and the outcome(s) measured made it difficult to compare these studies against each other and to generalize them to larger populations.

CONCLUSION

The findings of this review provide preliminary evidence for the positive impact of dietary interventions in the treatment of depressed patients. However, the mechanism by which particular diets induce positive changes in mood, be it through anti-inflammatory mechanisms or via weight loss in overweight patients, is unclear. Future research investigating the impact of dietary interventions on a large-scale is warranted and needed.

Personality Pathology in Winter Depression: Prevalence and Treatment Trajectories in Cognitive-Behavioral Therapy and Light Therapy

Personality disorders are highly comorbid with major depression; however, findings are mixed regarding their impact on depression treatment outcomes and trajectories. Limited research has studied personality pathology in winter depression, specifically. This study (1) explored the prevalence of personality pathology in winter depression and (2) examined its effects on winter depression treatment trajectories. Participants were 174 adults with Major Depression, Recurrent with Seasonal Pattern from a randomized clinical trial comparing group cognitive-behavioral therapy for seasonal affective disorder (CBT-SAD) and light therapy. Participants completed the Millon Clinical Multiaxial Inventory-III (MCMI-III; Millon et al., 1994) at baseline. The prevalence of MCMI-III-defined pathological personality traits and personality disorders in this sample was 98/174 (56.3%) with any trait and 65/174 (37.4%) with any disorder. Dependent was the most common elevation (65/174, 37.4%), trait (43/174, 24.7%), and disorder (22/174, 12.6%). Most participants with pathological personality elevations had only one personality disorder (58/174, 33.3%) and one pathological personality trait (82/174, 47.1%). Growth curve analysis revealed personality pathology predicted higher baseline depression scores, but the number of MCMI-III pathological personality elevations (i.e., traits and disorders) and personality disorders did not predict change in depression over the timeframe of pretreatment, weekly during treatment, posttreatment, and follow-ups one and two winters later in CBT-SAD or light therapy. Results suggest that personality pathology is not a negative prognostic indicator or prescriptive factor for winter depression treatment with CBT-SAD or light therapy, which may inform treatment algorithms and decision-making in practice.

Childhood maltreatment reports in adult seasonal affective disorder: Associations with sleep disturbances, maladaptive cognitions, and brooding

BACKGROUND

Although childhood maltreatment has been studied in multiple psychopathologies, its role in Seasonal Affective Disorder (SAD) is unknown. The current study examined possible mediators of the relationship between retrospectively-reported childhood maltreatment and adult SAD symptom severity during a major depressive episode in winter.

METHODS

Participants (N = 113), ages 18 to 65, completed measures of childhood maltreatment, SAD severity, sleep disturbances, ruminative brooding, and maladaptive cognitions. Mediation analyses testing the relationship between childhood maltreatment and SAD symptom severity via sleep and cognitive factors were conducted using PROCESS (Hayes, 2012).

RESULTS

Mediation analyses suggested that insomnia, hypersomnia, brooding, and seasonal maladaptive beliefs may account for the association between childhood maltreatment and SAD symptom severity.

LIMITATIONS

Analyses were cross-sectional and should be interpreted with caution. Participants completed self-report childhood trauma measure retrospectively as adults.

CONCLUSION

The present study is the first to examine childhood maltreatment in SAD, a disorder commonly viewed with circadian etiology. Covariance between childhood maltreatment and SAD symptom severity is indirectly explained by sleep difficulties, cognitive factors, and brooding, which may suggest therapeutic targets if replicated in longitudinal or experimental manipulations of sleep and cognition.

Seasonal and spatial variability of polychlorinated biphenyls (PCBs) in vegetation and cow milk from a high altitude pasture in the Italian Alps

The seasonal and spatial variability of polychlorinated biphenyls (PCBs) in vegetation and cow milk was studied in a high altitude pasture in the Alps (1900 m a.s.l.). PCB contamination in vegetation shows a concentration peak in June, which is mainly interpreted as the consequence of a temporary PCB enrichment of the air layer above the ground due to net emission fluxes from the soil. A three compartment dynamic model was developed to test this hypothesis. The North/South enrichment factor in the vegetation was 1.5-1.6 for penta- and hexa-substituted congeners and 1.7 for hepta- and octa-PCBs, according to the effect of temperature on compounds having higher K(oa) values. Milk concentrations followed the vegetation seasonal trend. The congener abundance in milk is in agreement with the biotransformation susceptibility, absorption efficiency and residence time of the different congeners in dairy cows.

Circadian uses of melatonin in humans

Melatonin in humans can be an independent or dependent variable. Measurement of endogenous melatonin levels under dim-light conditions, particularly the dim-light melatonin onset (DLMO), has received increasing attention among researchers, and for clinicians it may soon become a convenient test that can be done at home using saliva collections in the evening, without interfering with sleep. Melatonin, even at low physiological doses, can cause advances (shifts to an earlier time) or delays (shifts to a later time) depending on when it is administered on its phase-response curve (in most sighted people, these times are approximately in the p.m. and in the a.m., respectively). Although both bright light and melatonin can be used separately or together in the treatment of circadian phase disorders in sighted people-such as advanced and delayed sleep phase syndromes, jet lag, shift-work maladaptation, and winter depression (seasonal affective disorder, or SAD)-melatonin is the treatment of choice in totally blind people. These people provide a unique opportunity to study the human circadian system without the overwhelming effects of ocularly mediated light, thus permitting us to establish that all blind free-runners (BFRs) studied under high resolution appear to have phase-advancing and phase-delaying responses to as yet unidentified zeitgebers (time givers) that are usually too weak to result in entrainment.

Is SAD Lost to SAD?

Since 1984, 447 articles have been published using the acronym “SAD” for seasonal affective disorder in the heading of the publication, and since 1992, 59 articles have used “SAD” in the heading of the publication as an acronym for social anxiety disorder, according to MEDLINE. Using the acronym SAD for social anxiety disorder has been used with more frequency in recent scientific publications—interestingly, mostly in connection with newer antidepressants that have been found to be of therapeutic potential for this indication. To avoid possible confusions in research, the acronym “SOAD” was proposed for social anxiety disorder by Kasper and Winkler and “SAnD” by Nutt (D.J. Nutt, MD, PhD, unpublished data, 2004)—seemingly without success since these abbreviations are not seen in the literature. This month, CNS Spectrums focuses on the existing literature on the original acronym for SAD—seasonal affective disorder and its worldwide recognition.

In the early 1980s, Rosenthal and colleagues at the National Institute of Mental Health (NIMH) set out to describe a syndrome called SAD, not to be confused with the other, more recent SAD, social anxiety disorder. The original has been known to physicians since ancient times, dating back to Aretaeus the Cappadocian. However, the NIMH researchers for the first time systematically described the clinical symptomatology, compared it with healthy controls, and differentiated SAD from nonseasonal depression. Their work in tandem with emerging technology led to the discovery of the underlying pathophysiology of SAD and treatment approaches. The most important of these approaches were light therapy and pharmacotherapeutic options.

Measurement of illumination exposure in postpartum women

BACKGROUND

Low levels of light exposure at critical times are thought to cause seasonal affective disorder. Investigators, in studies demonstrating the usefulness of bright light therapy, also have implicated light's role in non-seasonal depression. The precise cause of postpartum depression has not been delineated, but it seemed possible that new mothers would spend reduced time in daylight. The goal of this study was to examine the levels of illumination experienced by postpartum mothers and to discover any relationship between light exposure and mood levels experienced during the postpartum period.

METHODS

Fifteen postpartum women, who did not have any baseline indication of depression, wore a wrist device (Actillume) for 72 hours to measure their exposure to light. At the end of the recording period, they completed a self-reported measure of mood. The mean light exposure of these postpartum women (expressed as the 24-hour average logarithm of illumination in lux) was compared with that of a representative sample of women of comparable age, residence, and seasonal months of recording. Mood levels were then rank-ordered and tested for correlation with light exposure levels.

RESULTS

There was no significant difference between the amount of light [log10lux] experienced by postpartum (1.01 SD 0.236) and control women (1.06 SD 0.285). Mood was not correlated with illumination in the postpartum sample.

CONCLUSIONS

Postpartum women in San Diego did not receive reduced light, nor was low mood related to low illumination.

Using client-side event logging and path tracing to assess and improve the quality of web-based surveys

Web-based data collection has considerable appeal. However, the quality of data collected using such instruments is often questionable. There can be systematic problems with the wording of the surveys, and/or the means with which they are deployed. In unsupervised data collection, there are also concerns about whether subjects understand the questions, and wehther they are answering honestly. This paper presents a schema for using client-side timestamps and traces of subjects' paths through instruments to detect problems with the definition of instruments and their deployment. We discuss two large, anonymous, web-based, medical surveys as examples of the utility of this approach.

Occurrence of suicide and seasonal variation

OBJECTIVE

To review the estimated suicide rates for the Region Metropolitan, the main socio-political center in Chile, for the period 1979-1994, and to determine whether they follow a seasonal pattern.

METHOD

Data available for the period 1979-94 at the Forensic Services in Chile was analyzed using Analyses of variance.

RESULTS

It was register 5,386 suicides. While the "warm" months (October, November, December & January) concentrated 39.0% of cases, the so called "cold" months reported 28.7%. This contrast is made even clearer by the month-to-month analysis, showing the highest suicide rate in December (10.6%) against the lowest rate in June (7.0%). Further statistical analysis revealed these differences to be significant.

CONCLUSION

The study shows that in Chile, representing as it does the Southern Hemisphere, the suicide rates tend to present a seasonal variation as has elsewhere been determined for in the North Hemisphere.

Bimodal patterns of human melatonin secretion consistent with a two-oscillator model of regulation

In many animals, changes in duration of nocturnal melatonin secretion chemically mediate effects of seasonal changes in nightlength on behavior and physiology. According to one model, the changes in duration of secretion result from adjustments in the timing of two circadian oscillators, one entrained to dusk, controlling onset, and another entrained to dawn, controlling offset. Consistent with this model, in six women, we found separate and reproducible evening and morning peaks of melatonin secretion that might represent the separate expressions of rhythms of two oscillators.