Biogenic amines in seasonal affective disorder: effects of light therapy

Seasonal variation of spontaneous blink rate and beta EEG activity

Seasonal variations of the photoperiod have been shown to regulate biological and behavioral functions, with also effects on clinical symptom and course of several psychiatric conditions. Although melatonin is considered the principal signal used to transmit informations about the light and dark cycle, a dopamine (DA) role in regulating seasonal changes has been suggested. Few studies have addressed a seasonal pattern of dopamine, and human studies have been conducted on inter-subject differences, comparing measures obtained during fall-winter with those of spring-summer. We studied within-subject seasonal changes of blink rate (BR), a indirect marker of central DA activity, in 26 normal subjects (15 females and 11 males, mean age: 24.7 ± 4.0) during winter, spring, summer and fall. Occipital EEG activity and subjective measures of vigilance and mood were also assessed to account for variations on arousal and fatigue. A significant seasonal effect was found for BR, with higher rate in summer, and for EEG beta activity, with higher activity in spring and summer. Subjective fatigue was found higher in winter. According to our data, it is possible that higher BR and increased EEG beta activity result by an arousal activation sustained by dopamine systems during the months with a long photoperiod.

Cerebrospinal fluid monoamine metabolite concentrations in depressive disorder: A meta-analysis of historic evidence

Altered monoaminergic functions have been implicated in the pathophysiology of depressive disorder. However, previously reported cerebrospinal fluid (CSF) monoamine metabolite concentrations in major depression have been inconsistent. We performed a meta-analysis of historic evidence to determine whether CSF monoamine metabolite levels were different between patients with depression and normal controls, and could be used as depression biomarkers. Relevant studies that investigated CSF 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) levels in patients with depression and normal controls were identified in PubMed, Web of Science, PsycINFO, and Embase databases through September 5, 2017, using a synonymous search for depression, CSF, normal, control, and each monoamine metabolite name, and in the reference lists of the acquired articles. Obtained records were individually scrutinized for eligibility. Our search strategy identified 26 studies, including our own. We employed random effects modeling and adopted "Hedges's g" as an index of effect size. In the meta-analyses, no significant difference was observed in CSF 5-HIAA or MHPG levels between patients with depressive disorder and controls. In contrast, CSF HVA was significantly decreased in patients with depression (Hedges's g = -0.30, P = 0.0000025), and these results remained significant after patients with bipolar disorder were excluded (Hedges's g = -0.37, P = 0.000061). In the meta-regression, sex was significantly associated with the Hedges's g of CSF HVA (Q = 4.41, P = 0.036). This meta-analysis revealed that only CSF HVA, and not 5-HIAA or MHPG, levels were decreased in depressive disorder. The reduction in the CSF HVA concentration in patients with depression may guide future studies on depression and serve as a useful biomarker of depressive disorder.

Bright light therapy for depression: a review of its effects on chronobiology and the autonomic nervous system

Bright light therapy (BLT) is considered among the first-line treatments for seasonal affective disorder (SAD), yet a growing body of literature supports its use in other neuropsychiatric conditions including non-seasonal depression. Despite evidence of its antidepressant efficacy, clinical use of BLT remains highly variable internationally. In this article, we explore the autonomic effects of BLT and suggest that such effects may play a role in its antidepressant and chronotherapeutic properties. After providing a brief introduction on the clinical application of BLT, we review the chronobiological effects of BLT on depression and on the autonomic nervous system in depressed and non-depressed individuals with an emphasis on non-seasonal depression. Such a theory of autonomic modulation via BLT could serve to integrate aspects of recent work centered on alleviating allostatic load, the polyvagal theory, the neurovisceral integration model and emerging evidence on the roles of glutamate and gamma-hydroxybutyric acid (GABA).

A systematic, updated review on the antidepressant agomelatine focusing on its melatonergic modulation

Objective:

To present an updated, comprehensive review on clinical and pre-clinical studies on agomelatine.

Method:

A MEDLINE, Psycinfo and Web of Science search (1966-May 2009) was performed using the following keywords: agomelatine, melatonin, S20098, efficacy, safety, adverse effect, pharmacokinetic, pharmacodynamic, major depressive disorder, bipolar disorder, Seasonal Affective Disorder (SAD), Alzheimer, ADHD, Generalized Anxiety Disorder (GAD), Panic Disorder (PD), Obsessive-Compulsive Disorder (OCD), anxiety disorders and mood disorder.

Study collection and data extraction:

All articles in English identified by the data sources were evaluated. Randomized, controlled clinical trials involving humans were prioritized in the review. The physiological bases of melatonergic transmission were also examined to deepen the clinical comprehension of agomelatine’ melatonergic modulation.

Data synthesis:

Agomelatine, a melatonergic analogue drug acting as MT₁/MT₂ agonist and 5-HT_2C antagonist, has been reported to be an effective antidepressant therapy.

Conclusions:

Although a bias in properly assessing the “sleep core” of depression may still exist with current screening instruments, therefore making difficult to compare agomelatine’ efficacy to other antidepressant ones, comparative studies showed agomelatine to be an intriguing option for depression and, potentially, for other therapeutic targets as well.

Sunshine-exposure variation of human striatal dopamine D(2)/D(3) receptor availability in healthy volunteers

BACKGROUND

In addition to the serotonergic system, the central dopaminergic system has been reported to be correlated with seasonality. The aim of this study was to explore the difference in striatal dopamine D(2)/D(3) receptor availability between healthy volunteers who had a high-sunshine exposure and those who had a low exposure.

METHODS

Sixty-eight participants were enrolled, and those in the upper and lower quartiles in terms of sunshine exposure were categorized into high- (n = 17) and low-sunshine-exposure (n = 18) subgroups. Single photon emission computed tomography with [(123)I] iodo-benzamide was used to measure striatal dopamine D(2)/D(3) receptor availability.

RESULTS

Striatal dopamine D(2)/D(3) receptor availability was significantly greater in the subjects with high-sunshine exposure than in those with low-sunshine exposure (F = 7.97, p = 0.01) after controlling for age, sex, and smoking status.

LIMITATIONS

Different subjects were examined at different time points in our study. In addition, the sex and tobacco use distributions differed between groups.

CONCLUSION

The central dopaminergic system may play a role in the neurobiological characteristics of sunshine-exposure variation.

The chronobiology and neurobiology of winter seasonal affective disorder

This review summarizes research on the chronobiology and neurobiology of winter seasonal affective disorder (SAD), a recurrent subtype of depression characterized by a predictable onset in the fall/winter months and spontaneous remission in the spring/summer period. Chronobiological mechanisms related to circadian rhythms, melatonin, and photoperiodism play a significant role in many cases of SAD, and treatment of SAD can be optimized by considering individual differences in key chronobiological markers. Converging evidence also points to a role for the major monoamine neurotransmitters serotonin, norepinephrine, and dopamine in one or more aspects of SAD. Ultimately, as with other psychiatric illnesses, SAD is best considered as a complex disorder resulting from the interaction of several vulnerability factors acting at different levels, the various genetic mechanisms that underlie them, and the physical environment. Models of SAD that emphasize its potential role in human evolution will also be discussed.

Circadian phase shifting, alerting, and antidepressant effects of bright light treatment

Bright light treatment is the most potent melatonin suppressor and circadian phase shifter and is a safe nonpharmacologic antidepressant for seasonal depression. In addition, bright light treatment may restore performance in conditions of sleep debt and misalignment between peak performance and the athletic event. This article discusses the therapeutic use of bright light treatment, its side effects, and mechanisms of action.

Light treatment of mood disorders

In 1981, seven patients with nonseasonal depression were treated with bright white light in 1982, bright artificial light was used to treat a manic-depressive patient with a seasonal mood cycle. In the last 20 years, a plethora of studies have further defined the depressive populations, who are responsive to light treatment; the optimal timing, intensity, spectral frequency, and duration of treatment; its comparison with other pharmacological interventions; predictors of response; side-effect profiles; viable placebo-control conditions; alternative devices and forms of administration; potential mechanisms and anatomical pathways mediating light's physiological effects; and its application to other disorders and subsyndromaI states. These studies have been conducted across multiple countries with surprisingly consistent results. Further work is needed, as highlighted in this review, to clarify the specific mechanism of action in subtypes of depressive disorders and differential age and gender effects. Although the majority of work in this area is relatively new, it behooves the reader to remember that Solomon, almost 3000 years ago, wrote in Ecclesiastes: "Truly the light is sweet and a pleasant thing it is for the eyes to behold the sun" (11:7).

Effect of sunlight and season on serotonin turnover in the brain

Alterations in monoaminergic neurotransmission in the brain are thought to underlie seasonal variations in mood, behaviour, and affective disorders. We took blood samples from internal jugular veins in 101 healthy men, to assess the relation between concentration of serotonin metabolite in these samples and weather conditions and season. We showed that turnover of serotonin by the brain was lowest in winter (p=0.013). Moreover, the rate of production of serotonin by the brain was directly related to the prevailing duration of bright sunlight (r=0.294, p=0.010), and rose rapidly with increased luminosity. Our findings are further evidence for the notion that changes in release of serotonin by the brain underlie mood seasonality and seasonal affective disorder.

Reboxetine in seasonal affective disorder: an open trial

Seasonal affective disorder (SAD), winter type, is a condition characterized by the annual recurrence of depressive episodes during fall/winter, alternating with spring/summer euthymia or hypomania. Various neurotransmitters have been implicated in the etiology of SAD, the strongest evidence involving serotonin. Recently, increasing attention has been paid to the potential role of catecholaminergic pathways in the pathophysiology of SAD. We investigated the efficacy and tolerability of reboxetine, a selective noradrenaline inhibitor, in patients with SAD. Eleven out of sixteen patients who were included in a 6-week drug surveillance during winter season experienced full remission of depressive symptoms. Nine patients reported a rapid relief of preexistent severe atypical depressive symptoms within the first treatment week. Reboxetine might therefore be an effective and well-tolerated treatment option for SAD patients. In conclusion, our preliminary results are in line with evidence from recent studies suggesting that catecholaminergic systems might also be involved in the pathophysiology of SAD.

Platelet [3H]paroxetine and [3H]lysergic acid diethylamide binding in seasonal affective disorder and the effect of bright light therapy

BACKGROUND

Seasonal affective disorder (SAD) has been regarded as a melatonin disorder, but the pathophysiological mechanisms of SAD are to a large extent unclarified. Serotonergic mechanisms have also been studied, but they have shown inconsistent results.

METHODS

We have compared [3H]paroxetine and [3H]lysergic acid diethylamide (LSD) binding in platelets from 23 SAD patients and 23 controls. Then SAD patients had 4 weeks of light therapy. On the last treatment day new blood samples were drawn. Symptoms before and after light treatment were measured by SIGH-SAD.

RESULTS

Bmax for paroxetine binding before light treatment was higher in SAD patients compared to controls and also higher in responders than in nonresponders. Bmax decreased significantly during light treatment. We also found a negative correlation between the two Bmax values before but not after light treatment. There was a negative correlation between Bmax for paroxetine binding before treatment and clinical status after treatment. Patients with reduced Bmax for LSD binding after treatment had a better clinical treatment response.

CONCLUSIONS

The present study indicates that serotonin receptor parameters might be suitable in the prediction of clinical response to light treatment.

The influence of climate on suicidal behaviour in Italy

A growing number of studies report an asymmetry in the seasonal distribution of suicides, with a peak in the late spring months for both sexes. The aim of this study is to verify if the climate, apart from its seasonal change, exerts a direct influence on suicidal behaviour. To this end, deaths by suicide in 17 Italian towns which all have a meteorologic station have been analyzed, taking into account some climatic indicators. Results of analyses show an unequal distribution of suicides with respect to latitude, with a peak in the North. The distribution of deaths by suicide shows a negative relationship with mean yearly temperature values, max and min, and with sun exposure indicators, and a positive, but less significant relationship with rainfall values. As far as climatic variables considered as a whole are concerned, stepwise regression identifies three relevant factors with significant relationships to suicide rates: humidity grade, rainfall mean, and sunlight exposure. These three climatic indicators explain up to 63% (Adj R2) of the variance in the distribution of suicide rates for both genders, with sunlight exposure offering the most significant contribution, when regressed on suicide rates via a multiple regression model. Higher suicide rates, therefore, correspond to dry places which are less exposed to the sun. However, the variable which shows the most significant correlation with suicide rates for both sexes is not a climatic one, but the percentage of the population aged 65 and over. The distribution of people at greater biological risk for possible disruption of brain neurochemistry (i.e. older people), therefore, predicts the distribution of suicide rates. Climate contributes to this biological risk by modifying both the responsiveness of the circuits that control mood and behaviour, and also the frequency and intensity of social interaction.

Cortisol in light treatment of seasonal and non-seasonal depression: relationship between melatonin and cortisol

The effect of bright light on cortisol and the relationship between melatonin and cortisol were studied in 63 depressed patients (42 patients with a seasonal pattern and 21 patients with a non-seasonal pattern). The patients were matched for age, time of treatment and severity of depression. Before and after light treatment the severity of the depression was rated with the Comprehensive Psychopathological Rating Scale (23 items) and the Hamilton Depression Rating scale (18 items), and serum cortisol and melatonin were drawn at nine time-points between 20.00 and 08.00 hours. Two hours of light treatment (350 cd m-2) was given daily for 10 days either in the morning (06.00-08.00 hours) or in the evening (18.00-20.00 hours). As reported earlier, patients with a seasonal pattern improved significantly more than patients with a non-seasonal pattern of depression, and no significant differences were found between the treatment efficacy of morning compared to evening light. A cosinor analysis showed that the cortisol batyphase was significantly advanced by morning light, but was not delayed by evening light. A delay in batyphase cortisol showed a weak significant correlation with a decrease in the absolute and relative sum of scores. The batyphase of cortisol occurred approximately 3 h earlier than the acrophase of melatonin. Of the changes in the melatonin acrophase 43% were reflected in a change of cortisol batyphase, indicating a hierarchical relationship with melatonin as the co-ordinating hormone transducing part of the information of the external light to the phase position of cortisol. No significant differences between patients with a seasonal or a non-seasonal pattern were seen in mesor, amplitude or batyphase of cortisol before treatment, and no significant changes in mesor or amplitude were seen as a result of light treatment.

The influence of ambient light and menstrual status on the moods of a nonclinical population of young women

OBJECTIVE

To study the influence of the daily variation in ambient light and menstrual status on mood fluctuation in a nonclinical population of young women.

METHODS

Women kept mood diaries (two per day) over a period of 32 days that straddled the spring equinox. One group believed the purpose of the study was to investigate women's moods are significantly elevated by light, and this elevation occurs irrespective of the subjects knowledge of the experimental purpose. No evidence for a depression of women's mood in the premenstruum was found, although women who claimed to suffer from premenstrual syndrome (PMS) showed more reversals of their mood during the 32 days records were kept.

CONCLUSIONS

The results highlight the fact that an individual's mood may be influenced by the levels of ambient light as well as the photoperiod.

The influence of seasonal change on suicidal behaviour in Italy

The seasonal variance of suicides and attempted suicides in Italy from 1974 to 1994 has been studied to determine the extent and the nature of the seasonal influence on suicidal behaviour. The relationship between some climatic factors and suicide and attempted suicide rates has also been analyzed. A significant effect of seasonal change on suicidal behavior, with a clear peak in spring has been detected (ANOVA: df = 3/248, F = 5.875, p = 0.0007 for suicide; df = 3/248, F = 6.198, p = 0.0004 for attempted suicide), with a greater seasonal effect on males than females. The monthly distribution of suicide deaths and of attempted suicides follows a significant direct relationship with exposure to sun, and an inverse relationship with rainfall levels. So, one of the possible explanations for the effect of seasonal change on suicidal behaviour could be the changing seasonal climate. The complex influence of seasonal climate on human biological rhythms, particularly on 5-HT (serotonin) related functions, together with its effects on sociorelational habits, should be considered for suicide prevention.

Effect of bright light exposure on muscle sympathetic nerve activity in human

To evaluate the effect of bright light on the sympathetic nervous system in human, muscle sympathetic nerve activity (MSNA) was recorded from the peroneal nerve in five healthy subjects. Each subject was exposed to bright light of 5000 lx for 20 min. After the bright light exposure, MSNA became significantly enhanced. The heart rate increased transiently only during the bright light exposure. The blood pressure did not change significantly during and after the bright light exposure. The result is the first direct evidence showing that bright light modulates the activity of the sympathetic nervous system in normal human.

Effect of light and season on pain and depression in subjects with rheumatic disorders

The clinical and neurochemical association between depression and season noted in seasonal affective disorder (SAD) has suggested that clinical pain might also be linked to season, perhaps through similar neurochemistry or the known association of depression with pain. We investigated the pain-light season/dark season hypothesis in 2523 rheumatic disease outpatients by examining VAS Pain and VAS Global Severity scores, as well as levels of depression and functional disability. No clinically significant difference in pain severity between season (or individual month) was noted for the consecutive outpatients at their first clinic visit, nor in sub-analyses using paired light and dark season visits. A slight trend toward increased pain severity in lighter months by about 3% compared to darker months was identified. No effect of season was seen on depression scores. In a subset of patients with high depression scores, rheumatoid arthritis and osteoarthritis patients, respectively, reported 16% and 7% greater pain scores in light compared to dark months, but fibromyalgia patients had stable scores. Season does not appear to play an important role in pain and/or depression in rheumatic disorders.