Seasonal affective disorder: a review of the syndrome and its public health implications

The underexplored presence of seasonal affective disorder in the southern hemisphere: A narrative review of the Australian literature

BACKGROUND

Seasonal Affective Disorder (SAD) is well documented in the medical literature, particularly in more northern latitudes in agreement with proposed hypotheses for SAD's pathophysiology. However, in the southern latitudes SAD's presence remains underexplored. The second largest country in the southern hemisphere is Australia. Australia has wide ranging geographical and climatic differences that are expected to support SAD's presence. The aim of this study is therefore, to establish an evidence base for SAD in Australia.

METHODS

PubMed and Google Scholar were searched for published peer-review studies focussed on, or related to SAD, winter depression or seasonal variation in mood in Australia. There were no time-period restrictions.

RESULTS

Thirteen studies were identified. Studies explored the presence/nature of SAD, contributing factors, autonomic activity, treatment, and the validity of the Seasonal Pattern Assessment Questionnaire in the Australian population. An association between changes in mood and behaviour and seasonal occurrence was clearly identified, with SAD's presence varying by location. The highest percentage of study participants with SAD in a single location was observed in Tasmania, Australia's most southern state. The findings and interpretations of the studies included in this review are subject to the number of locations assessed, the number of studies undertaken at each location and individual study limitations.

CONCLUSIONS

Ascertaining information on the prevalence and correlates of SAD in the southern hemisphere, particularly in high-risk locations could contribute to clinical literacy into the syndrome, support management practices, and promote the early identification and treatment of the disorder.

Efficacy of low carbohydrate and ketogenic diets in treating mood and anxiety disorders: systematic review and implications for clinical practice

BACKGROUND

There is mounting interest in the potential efficacy of low carbohydrate and very low carbohydrate ketogenic diets in various neurological and psychiatric disorders.

AIMS

To conduct a systematic review and narrative synthesis of low carbohydrate and ketogenic diets (LC/KD) in adults with mood and anxiety disorders.

METHOD

MEDLINE, Embase, PsycINFO and Cochrane databases were systematically searched for articles from inception to 6 September 2022. Studies that included adults with any mood or anxiety disorder treated with a low carbohydrate or ketogenic intervention, reporting effects on mood or anxiety symptoms were eligible for inclusion. PROSPERO registration CRD42019116367.

RESULTS

The search yielded 1377 articles, of which 48 were assessed for full-text eligibility. Twelve heterogeneous studies (stated as ketogenic interventions, albeit with incomplete carbohydrate reporting and measurements of ketosis; diet duration: 2 weeks to 3 years; n = 389; age range 19 to 75 years) were included in the final analysis. This included nine case reports, two cohort studies and one observational study. Data quality was variable, with no high-quality evidence identified. Efficacy, adverse effects and discontinuation rates were not systematically reported. There was some evidence for efficacy of ketogenic diets in those with bipolar disorder, schizoaffective disorder and possibly unipolar depression/anxiety. Relapse after discontinuation of the diet was reported in some individuals.

CONCLUSIONS

Although there is no high-quality evidence of LC/KD efficacy in mood or anxiety disorders, several uncontrolled studies suggest possible beneficial effects. Robust studies are now needed to demonstrate efficacy, to identify clinical groups who may benefit and whether a ketogenic diet (beyond low carbohydrate) is required and to characterise adverse effects and the risk of relapse after diet discontinuation.

Low Daytime Light Intensity Disrupts Male Copulatory Behavior, and Upregulates Medial Preoptic Area Steroid Hormone and Dopamine Receptor Expression, in a Diurnal Rodent Model of Seasonal Affective Disorder

Seasonal affective disorder (SAD) involves a number of psychological and behavioral impairments that emerge during the low daytime light intensity associated with winter, but which remit during the high daytime light intensity associated with summer. One symptom frequently reported by SAD patients is reduced sexual interest and activity, but the endocrine and neural bases of this particular impairment during low daylight intensity is unknown. Using a diurnal laboratory rodent, the Nile grass rat (Arvicanthis niloticus), we determined how chronic housing under a 12:12 h day/night cycle involving dim low-intensity daylight (50 lux) or bright high-intensity daylight (1,000 lux) affects males’ copulatory behavior, reproductive organ weight, and circulating testosterone. We also examined the expression of mRNAs for the aromatase enzyme, estrogen receptor 1 (ESR1), and androgen receptor (AR) in the medial preoptic area (mPOA; brain site involved in the sensory and hormonal control of copulation), and mRNAs for the dopamine (DA) D1 and D2 receptors in both the mPOA and nucleus accumbens (NAC; brain site involved in stimulus salience and motivation to respond to reward). Compared to male grass rats housed in high-intensity daylight, males in low-intensity daylight displayed fewer mounts and intromissions when interacting with females, but the groups did not differ in their testes or seminal vesicle weights, or in their circulating levels of testosterone. Males in low-intensity daylight unexpectedly had higher ESR1, AR and D1 receptor mRNA in the mPOA, but did not differ from high-intensity daylight males in D1 or D2 mRNA expression in the NAC. Reminiscent of humans with SAD, dim winter-like daylight intensity impairs aspects of sexual behavior in a male diurnal rodent. This effect is not due to reduced circulating testosterone and is associated with upregulation of mPOA steroid and DA receptors that may help maintain some sexual motivation and behavior under winter-like lighting conditions.

Sunlight Brightens Learning and Memory

Sunlight can alter mood, behavior, and cognition, but the cellular basis of this phenomenon remains to be fully elucidated. In this issue of Cell, Zhu et al. shed light on a UV-dependent metabolic pathway that leads to increased synaptic release of glutamate and enhanced motor learning and memory in mice.

Blue light filtered white light induces depression-like responses and temporary spatial learning deficits in rats

OBJECTIVES

Ambient light has a vital impact on mood and cognitive functions. Blue light has been previously reported to play a salient role in the antidepressant effect via melanopsin. Whether blue light filtered white light (BFW) affects mood and cognitive functions remains unclear. The present study aimed to investigate whether BFW led to depression-like symptoms and cognitive deficits including spatial learning and memory abilities in rats, and whether they were associated with the light-responsive function in retinal explants.

METHODS

Male Sprague-Dawley albino rats were randomly divided into 2 groups (n = 10) and treated with a white light-emitting diode (LED) light source and BFW light source, respectively, under a standard 12 : 12 h L/D condition over 30 days. The sucrose consumption test, forced swim test (FST) and the level of plasma corticosterone (CORT) were employed to evaluate depression-like symptoms in rats. Cognitive functions were assessed by the Morris water maze (MWM) test. A multi-electrode array (MEA) system was utilized to measure electro-retinogram (ERG) responses induced by white or BFW flashes.

RESULTS

The effect of BFW over 30 days on depression-like responses in rats was indicated by decreased sucrose consumption in the sucrose consumption test, an increased immobility time in the FST and an elevated level of plasma CORT. BFW led to temporary spatial learning deficits in rats, which was evidenced by prolonged escape latency and swimming distances in the spatial navigation test. However, no changes were observed in the short memory ability of rats treated with BFW. The micro-ERG results showed a delayed implicit time and reduced amplitudes evoked by BFW flashes compared to the white flash group.

CONCLUSIONS

BFW induces depression-like symptoms and temporary spatial learning deficits in rats, which might be closely related to the impairment of light-evoked output signals in the retina.

Raison d'être of insulin resistance: the adjustable threshold hypothesis

The epidemics of obesity and diabetes demand a deeper understanding of insulin resistance, for which the adjustable threshold hypothesis is formed in this paper. To test the hypothesis, mathematical modelling was used to analyse clinical data and to simulate biological processes at both molecular and organismal levels. I found that insulin resistance roots in the thresholds of the cell's bistable response. By assuming heterogeneity of the thresholds, single cells' all-or-none response can collectively produce a graded response at the whole-body level-conforming to existing data. The thresholds have to be adjustable to adapt to extreme conditions. During pregnancy, for example, the thresholds increase consistently to strengthen the mother's insulin resistance to meet the increasing glucose demand of the expanding fetal brain. I also found that hysteresis, a key element of the adjustable threshold hypothesis, can explain reactive hypoglycaemia, which is characteristic of diabetes complications but remains poorly understood. Contrary to the common belief that insulin promotes glucose disposal, the results imply that insulin is the body's 'ration stamp' to restricting glucose utilization by peripheral tissues and that insulin resistance is primarily a well-evolved mechanism. The hypothesis provides an intuitive and dynamical description of the previously formless insulin resistance, which may make the detection of pre-diabetes possible and may shed light on the optimal timing of therapeutic intervention. It also provides valuable clues to defining subtypes of type 2 diabetes that might respond differently to specific prevention and intervention strategies.

Chronotype and seasonality: morningness is associated with lower seasonal mood and behavior changes in the Old Order Amish

BACKGROUND

Several studies documented that lower scores on the Morningness-Eveningness Questionnaire (MEQ) are associated with a higher global seasonality of mood (GSS). As for the Modern Man artificial lighting predominantly extends evening activity and exposure to light, and as evening bright light phase is known to delay circadian rhythms, this chronic exposure could potentially lead to both lower Morningness as well as higher GSS. The aim of the study was to investigate if the MEQ-GSS relationship holds in the Old Order Amish of Lancaster County, PA, a population that does not use network electrical light.

METHODS

489 Old Order Amish adults (47.6% women), with average (SD) age of 49.7 (14.2) years, completed both the Seasonal Pattern Assessment Questionnaire (SPAQ) for the assessment of GSS, and MEQ. Associations between GSS scores and MEQ scores were analyzed using linear models, accounting for age, gender and relatedness by including the relationship matrix in the model as a random effect.

RESULTS

GSS was inversely associated with MEQ scores (p=0.006, adjusted).

LIMITATIONS

include a potential recall bias associated with self-report questionnaires and no actual light exposure measurements.

CONCLUSION

We confirmed the previously reported inverse association between MEQ scores and lower seasonality of mood, for the first time in a population that does not use home network electrical lighting. This result suggests that the association is not a byproduct of exposure to network electric light, and calls for additional research to investigate mechanisms by which Morningness is negatively associated with seasonality.

Altered resting-state activity in seasonal affective disorder

At present, our knowledge about seasonal affective disorder (SAD) is based mainly up on clinical symptoms, epidemiology, behavioral characteristics and light therapy. Recently developed measures of resting-state functional brain activity might provide neurobiological markers of brain disorders. Studying functional brain activity in SAD could enhance our understanding of its nature and possible treatment strategies. Functional network connectivity (measured using ICA-dual regression), and amplitude of low-frequency fluctuations (ALFF) were measured in 45 antidepressant-free patients (39.78 ± 10.64, 30 ♀, 15 ♂) diagnosed with SAD and compared with age-, gender- and ethnicity-matched healthy controls (HCs) using resting-state functional magnetic resonance imaging. After correcting for Type 1 error at high model orders (inter-RSN correction), SAD patients showed significantly increased functional connectivity in 11 of the 47 identified RSNs. Increased functional connectivity involved RSNs such as visual, sensorimotor, and attentional networks. Moreover, our results revealed that SAD patients compared with HCs showed significant higher ALFF in the visual and right sensorimotor cortex. Abnormally altered functional activity detected in SAD supports previously reported attentional and psychomotor symptoms in patients suffering from SAD. Further studies, particularly under task conditions, are needed in order to specifically investigate cognitive deficits in SAD.

Potential animal models of seasonal affective disorder

Seasonal affective disorder (SAD) is characterized by depressive episodes during winter that are alleviated during summer and by morning bright light treatment. Currently, there is no animal model of SAD. However, it may be possible to use rodents that respond to day length (photoperiod) to understand how photoperiod can shape the brain and behavior in humans. As nights lengthen in the autumn, the duration of the nightly elevation of melatonin increase; seasonally breeding animals use this information to orchestrate seasonal changes in physiology and behavior. SAD may originate from the extended duration of nightly melatonin secretion during fall and winter. These similarities between humans and rodents in melatonin secretion allows for comparisons with rodents that express more depressive-like responses when exposed to short day lengths. For instance, Siberian hamsters, fat sand rats, Nile grass rats, and Wistar rats display a depressive-like phenotype when exposed to short days. Current research in depression and animal models of depression suggests that hippocampal plasticity may underlie the symptoms of depression and depressive-like behaviors, respectively. It is also possible that day length induces structural changes in human brains. Many seasonally breeding rodents undergo changes in whole brain and hippocampal volume in short days. Based on strict validity criteria, there is no animal model of SAD, but rodents that respond to reduced day lengths may be useful to approximate the neurobiological phenomena that occur in people with SAD, leading to greater understanding of the etiology of the disorder as well as novel therapeutic interventions.

Viral carrier status is instilled by viral regulatory particles

Human viral carriers are important agents in the periodic resurgence of many pathogens. Instillation of virus in human carriers explains several of the unusual epidemiological features of viral epidemics, such as where viruses linger between epidemics and how epidemics can arise without an apparent source. By inactivating itself, a virus can easily reside in a host for months or years without being noticed by the immune system, enabling the virus to be dispersed inconspicuously in the future and into new regions. When this silent activity of human carriers is appreciated, it is easier to understand the dynamics of viral epidemics, such as the explosive appearance of influenza epidemics. During viral illnesses, virus in infected cells is put into a latent state by regulatory sequences delivered by particles produced by other virus-infected cells. These regulatory particles are similar to the virus's virion but contain specific subsets of the viral genome and cannot replicate in cells that are not infected by the complete viral genome. Regulatory particles have previously been referred to as defective interfering particles, noninfective viruses, inactive viruses, incomplete viruses, satellite viruses, and defective viruses. There are still many unanswered questions regarding viral carrier creation and the role human carriers play in the pathology and epidemiology of viral diseases. Some of these questions are presented and discussed in relation to regulatory particles, possible investigations and how carrier status may affect the health of the carrier. Viral regulatory particles limit the extent of viral infections and shift the active infection to a latent infection. Just as multicellular creatures use hormones as chemical messengers to coordinate cellular functions, viruses utilize regulatory particles to coordinate viral modes among infected cells within a host. Many viruses depend on these particles for their continued existence. If we wish to comprehend and effectively treat viral infections, we must secure a thorough understanding of viral regulatory particles.

Seasonal affective disorder and its prevention by anticipatory treatment with bupropion XL

BACKGROUND

Seasonal affective disorder (SAD) can cause significant distress and impairment. No antidepressant studies have previously attempted to prevent the onset of autumn-winter depression.

METHODS

Three prospective, randomized, placebo-controlled prevention trials were conducted on 1042 SAD patients, enrolled in autumn and treated while still well, across the northern US and Canada. Patients received either bupropion XL 150-300 mg or placebo daily by mouth from enrollment until spring and were then followed off medications for 8 additional weeks. Primary efficacy variables were end-of-treatment depression-free rates and survival distributions of depressive recurrence.

RESULTS

Despite a reported average of 13 previous seasonal depressive episodes, almost 60% of patients had never previously been treated for depression. Major depression recurrence rates during the three studies for bupropion XL and placebo groups were 19% versus 30% (p = 0.026), 13% versus 21% (p = 0.049), and 16% versus 31%; yielding a relative risk reduction across the three studies of 44% for patients taking bupropion XL. Survival analyses for depression onset also favored bupropion XL over placebo (p = .081, .057, and <.001).

CONCLUSIONS

It is possible to prevent recurrence of seasonal major depressive episodes by beginning bupropion treatment early in the season while patients are still well.

Lack of seasonal variations in fertilization, pregnancy and implantation rates in women undergoing IVF

BACKGROUND

Several studies have investigated seasonal variations during IVF. Their results are contradictory, especially concerning fertilization and pregnancy rates. The aim of the present study was to re-evaluate these parameters using a large number of IVF cycles.

METHODS

A total of 7368 IVF cycles conducted in Switzerland between 1995 and 2003 were retrospectively analysed. To avoid a bias in the evaluation of the fertilization rate, only IVF cycles without ICSI were considered for analysis. Cycles were assigned to seasons according to the date of the beginning of stimulation.

RESULTS

There were no statistically significant differences between the seasons concerning the fertilization, the pregnancy and the implantation rates. However, statistically significant variables deciding on the outcome of an IVF cycle are age, centre, aetiology of infertility and day of transfer.

CONCLUSIONS

There were no statistically significant seasonal differences in central Europe (Switzerland) that influenced the outcome of IVF treatment. The only statistically significant variables of IVF outcome were age, centre, aetiology of infertility and day of transfer. A change to routine fertility treatment concerning the different seasons should therefore not be taken into account.

Seasonal variation of blood cholesterol levels: study methodology

This manuscript provides a description of the methodology used in the Seasonal Variation of Blood Cholesterol Levels (SEASON) study, with the intent of informing the scientific community of the available data sets and to invite a dialogue with scientists in complementary fields. The primary aim of the SEASON study is to describe and delineate the causes of seasonal variation of blood lipid levels in the general population. This research project is designed specifically to systematically collect and analyze a number of important variables necessary to study the role of seasonality in blood lipids and relevant covariates.

Core body temperature is normal in chronic fatigue syndrome

BACKGROUND

Subjects with chronic fatigue syndrome (CFS) frequently report symptoms of subnormal body temperature and low-grade fever. We conducted a study to determine whether CFS subjects manifest any abnormality of core body temperature (CBT) that might help explain their fatigue.

METHODS

Continuous 24-hour recordings of CBT measured every 5 min were performed in 7 subjects meeting the Centers for Disease Control definition of CFS. Three additional groups were studied: normal controls, subjects with seasonal allergy, and subjects with major depression. Subjects (n = 7) in each group were age-, sex-, and weight-matched to the CFS group and had normal basal metabolic rates, thyroid function, and 24-hour urinary free cortisol excretions. CBT was measured with an ingestible radio frequency transmitter pill and a belt-worn receiver-logger. Each pill was factory-calibrated to +/- 0.1 degree C and field-calibrated with a water bath calibration prior to use.

RESULTS

The 24-hour mean calibration-adjusted CBTs of each group were not significantly different (control: 37.00 +/- 0.17 degrees C; CFS: 37.04 +/- 0.31 degrees C; allergy: 37.15 +/- 0.18 degrees C; depression: 37.16 +/- 0.18 degrees C). Similarly, the mean peak and trough circadian temperatures were not statistically different. The mean 24-hour profile of CBT for each group showed a similar circadian rhythm. In simultaneously collected blood samples, each group showed a similar circadian profile of serum cortisol with a peak occurring at 08:00.

CONCLUSIONS

Subjects with CFS have normal CBT despite frequent self-reports of subnormal body temperature and low-grade fever.

Seasonal changes in affective state in samples of Asian and white women

Seasonality of the affective state has been reported to vary in direct proportion to latitude in temperate regions. The frequency of seasonal affective disorder (SAD) and the severity of the symptoms associated with it have been reported to be greater in higher than in lower latitudes. In addition, recent research has suggested a genetic loading for SAD. Most of the research on the seasonality of affect has been done in high latitude areas, seasonal mood cycles have been infrequently investigated in tropical areas, and no study has so far measured and compared seasonal changes in affect and behaviour in indigenous and populations non-indigenous to high latitudes. To rule out the biases associated with retrospective designs, a prospective longitudinal study was designed to investigate seasonal mood variations in indigenous white and non-indigenous Asian populations. Since previous research has indicated the excessive vulnerability of women to winter depression, it was decided to measure seasonality of the affective state only in women. To examine the relative effects of genetic predispositions and physical environment, the Asian group was further divided into "Asian" and "Asian-British". The former group comprised women who were living in England but who had been born and had spent considerably more time in their country of origin, while the latter group consisted of women who were born in England and who had lived there all their lives. The three groups of 25 women each were matched for age and socio-economic status, and were interviewed every month for 1 year using the Hospital Anxiety and Depression Scale (HAD), a Behavioural Change Inventory (BCI), the Ladder Scale of General Well-being (LSW) and a Monthly Stress Inventory (MSI). One retrospective scale was administered at the end of the study year to compare the extent of seasonal change in affect with that on the HAD-depression subscale. The results showed that seasonal depression peaked in winter in all three groups, with the incidence of winter depression being highest in the Asian group. Seasonal changes on several dimensions of behaviour were in the direction of winter depression for all three groups. States other than depression (anxiety and general well-being) did not show any seasonal variation. Hours of daylight was found to be the best predictor of seasonal variation in mood among environmental and psychosocial variables. There was no evidence to support a genetic hypothesis for SAD.

Prevention of winter seasonal affective disorder by bright-light treatment

In patients with winter seasonal affective disorder (SAD) the onset of a depressive episode is probably associated with the decreasing amount of light during the autumn. A highly predictable onset of a recurrent depressive episode with seasonal pattern provides a rationale for testing the efficacy of bright-light treatment as a preventive measure. Twelve out-patients with winter SAD were assigned to start bright light treatment either when they were well, or not to start it until the first symptoms of depression had already emerged. The severity of depressive symptoms was prospectively rated for a parallel randomized comparison. Bright light given well in advance of the emerging symptoms prevented a depressive episode. Clinical remission was significantly more frequent in the former subgroup of the patients in January and in March. To sum up, bright light can be successfully administered as prophylactic treatment for the prevention of winter SAD.

A seasonal pattern of hospital medication errors in Alaska

Specific behavioral consequences of seasonal affective disorder have not been closely examined. Length of daylight is evaluated in relation to medication errors in a medical center located in the far north. Factors such as numbers of patient admissions, discharges, and deaths were controlled with data collected in Anchorage, Alaska, over 5 consecutive years, 1985-89. These data revealed that 58% of all medication errors occurred during the first quarter of the year. Medication errors were 1.95 times more likely in December than September. The best statistical prediction was for errors associated with levels of darkness 2 months earlier. There may be not only an impairment of work performance among hospital nursing staff that reaches a peak in late winter but, more importantly, medication errors appear to follow a pattern that is closely associated with the annual cycle of daylight and darkness.

Take heart: results from the initial phase of a work-site wellness program

OBJECTIVES

The purpose of this study was to evaluate the short-term effects of a low-intensity work-site heart disease risk reduction program using a matched pair design with work site as the unit of analysis.

METHODS

Twenty-six heterogeneous work sites with between 125 and 750 employees were matched on key organization characteristics and then randomly assigned to early or delayed intervention conditions. Early intervention consisted of an 18-month multifaceted program that featured an employee steering committee and a menu approach to conducting key intervention activities tailored to each site.

RESULTS

Cross-sectional and cohort analyses produced consistent results. At the conclusion of the intervention, early and delayed intervention conditions did not differ on changes in smoking rates, dietary intake, or cholesterol levels. There was considerable variability in outcomes among work sites within each condition.

CONCLUSIONS

Despite documented implementation of key intervention activities and organization-level changes in terms of perceived support for health promotion, this intervention did not produce short-term improvements beyond secular trends observed in control work sites. Research is needed to understand determinants of variability between work sites.

Anxiety disorders and anxiety symptoms in a clinic sample of seasonal and non-seasonal depressives

Thirty-eight patients with seasonal affective disorder (SAD) were compared with 33 non-seasonal recurrent major depressives (non-SAD) who presented during the winter months for differences in the prevalence of concurrent anxiety disorders and the impact of anxiety on treatment response. SAD patients received light therapy, whereas non-SAD patients received antidepressant medications. There was no differences in the prevalence of any anxiety disorder, or on scores of anxiety on the Hamilton Rating Scale for Depression between the SAD and non-SAD groups. The presence of any anxiety disorder was associated with a better response rate in SAD patients, and an inferior response rate in non-SAD patients. The findings refute previous suggestions that anxiety is more common in SAD than in non-SAD, but suggest that the presence of anxiety may be associated with differential treatment response rates.

The circadian rhythm of body temperature

This paper reviews the literature on the circadian rhythm of body temperature (CRT). The review starts with a brief discussion of methodological procedures followed by the description of known patterns of oscillation in body temperature, including ultradian and infradian rhythms. Special sections are devoted to issues of species differences, development and aging, and the relationships between the CRT and the circadian rhythm of locomotor activity, between the CRT and the thermoregulatory system, and between the CRT and states of disease. A section on the nervous control of the CRT is followed by summary and conclusions.

Seasonal affective disorder, the depression of winter: a literature review and description from a nursing perspective

This article presents a literature review and description of seasonal affective disorder (SAD). SAD is a newly recognized disorder, differentiated from other affective illnesses by its seasonality (with midwinter dysthymia and spring/summer remission), and its atypical symptoms of hypersomnia and hyperphagia. SAD symptoms remit with travel towards the equator or with bright light treatments, possibly indicating a chronobiological circadian etiology. This article introduces aspects of SAD that are amenable to the nursing process, including assessment of the seasonality of dysthymic symptoms; diagnoses of patient responses; referral, education, and psychotherapeutic interventions; and evaluation of patient responses to interventions. Since SAD is found predominantly in young women, and because symptoms may be exacerbated by rotating shifts, it is possible that nurses may have a higher incidence of SAD, compared with other professions.

The effects of phototherapy in the general population

Patients with recurrent winter depression and its subsyndromal form have been reported to benefit from bright full-spectrum light (phototherapy). In order to determine whether this treatment (2 h in the morning) during winter is effective in a random sample of the general population we investigated the responses of 20 subjects with varying degrees of winter difficulties. A control group (n = 20) matched for the degree of seasonality, age, and sex was treated with dim light. Individuals were selected from a larger survey sample of the Montgomery County population (MD, U.S.A.) and were comparable to the latter in their degree of winter difficulties. Enhancement of environmental light does not, on the basis of the present study, appear to be indicated for the public at large, but rather for a subgroup of individuals with histories of winter difficulties.

Depression in late life: an update

Clinical and basic research units depressive disorders in late life have expanded our knowledge base appreciably in recent years. In the process, some clinical impressions have been confirmed (e.g., the association of depression and physical disorders); others have been refuted (e.g., depression increases with age); and now phenomena have been identified (e.g., the discovery of leukoencephalopathy in depressant elders who respond to ECT). The field of study now encompasses a range from neurobiology to sociocultural factors. The latter twentieth century is an exciting and optimistic era for clinicians working with depressed elders. As Sir Martin Roth has often said, "Where there is depression in late life, there is hope."

Light, vitamin D and psychiatry. Role of 1,25 dihydroxyvitamin D3 (soltriol) in etiology and therapy of seasonal affective disorder and other mental processes

This is a review and a prospectus of effects of vitamin D on the brain. Effects of sunlight and equivalent artificial light on physiological and behavioral processes are probably mediated, in large part, through the skin-vitamin D-endocrine system. Experimental evidence from our laboratory reveals sites of action and concomitant direct effects of 1,25(OH)2 vitamin D3 (soltriol) on brain, spinal cord, pituitary and other endocrine tissues. This appears relevant for the activation and modulation of mental and endocrine processes, particularly related to seasonal and daily biorhythms. Effects of sunlight and corresponding artificial light are likely to be mediated through direct actions of soltriol on brain and endocrine tissues that are independent of its effect on calcium levels. Those direct actions are receptor mediated and appear to be dose related as they depend on intensity of light and length of exposure, considering light (photons) as a drug. A role for soltriol, the steroid hormone of sunlight, in the etiology and helio- or phototherapy of affective disorders with cyclic seasonal onset (seasonal affective disorder) is discussed and the significance of research in the new frontier of vitamin D and brain relationships is noted.