Disrupted relationship between blood glucose and brain dopamine D2/3 receptor binding in patients with first-episode schizophrenia

An elemental function of brain dopamine is to coordinate cognitive and motor resources for successful exploitation of environmental energy sources. Dopamine transmission, goal-directed behavior, and glucose homeostasis are altered in schizophrenia patients prior to and after initiation of pharmacological treatment. Thus, we investigated the relationship between blood glucose levels and brain dopamine signaling in drug-naïve patients with first-episode psychosis. We quantified blood glucose levels and binding of the dopamine D_2/3 receptor agonist radioligand (+)-[¹¹C]-PHNO in 15 medication-naïve patients and 27 healthy volunteers employing positron emission tomography. Whole-brain voxel-wise linear model analysis identified two clusters of significant interaction between blood glucose levels and diagnosis on (+)-[¹¹C]-PHNO binding-potential values. We observed positive relationships between blood glucose levels and binding-potential values in healthy volunteers but negative ones in patients with first episode psychosis in a cluster surviving rigorous multiple testing correction located in the in the right ventral tegmental area. Another cluster of homologous behavior, however at a lower level of statistical significance, comprised the ventral striatum and pallidum. Extracellular dopamine levels are a major determinant of (+)-[¹¹C]-PHNO binding in the brain. In line with the concept that increased dopamine signaling occurs when goal-directed behavior is needed for restoring energy supply, our data indicate that in healthy volunteers, extracellular dopamine levels are high when blood glucose levels are low and vice-versa. This relationship is reversed in patients with first-episode psychosis, possibly reflecting an underlying pathogenic alteration that links two seemingly unrelated aspects of the illness: altered dopamine signaling and dysfunctional glucose homeostasis.

Neurochemical and behavioral sensitization to d-amphetamine in healthy subjects measured with [11C]-(+)-PHNO-PET

Introduction

It has been shown that patients with schizophrenia are super-sensitive towards dopamine-releasing agents such as amphetamine. Here, we studied the effects of amphetamine sensitization on amphetamine-induced dopamine release in healthy subjects.

Objectives

To measure d-amphetamine-induced dopamine release as measured with the D2,3 agonist radioligand [11C]-(+)-PHNO-PET via change in non-displacable binding potential (BPND) and behavioral measures of d-amphetamine effects with drug effects questionnaire (DEQ) and subjective states questionnaire (SSQ).

Aims

To study d-amphetamine-induced sensitization in healthy subjects on a behavioral and neurochemical level with [11C]-(+)-PHNO-PET in order to gain more knowledge on sensitization-induced changes in the dopaminergic system.

Methods

Twelve stimulant-naïve healthy male subjects underwent three 90-min [11C]-(+)-PHNO-PET-scans and four oral administrations of d-amphetamine. After a naïve baseline scan, subjects underwent a PET scan with previous ingestion of 0.4 mg/kg bodyweight of d-amphetamine 90–120 minutes before scanning. Subsequently, subjects were sensitized to d-amphetamine with the same dose on two separate days. Thereafter, they underwent another PET scan with previous d-amphetamine ingestion. DEQ and SSQ were administered before, 60 min, 90–120 min, and 210 min after amphetamine ingestion.

Results

We found significant sensitization effects on a behavioral level and on a neurochemical level after four administrations of amphetamine. Items of the SSQ, which showed significant sensitization effects were “outgoing”, “energetic”, “lively”, “alert” and “focused”.

Conclusions

We were able to induce significant behavioral and neurochemical sensitization in healthy humans, which were measured with [11C]-(+)-PHNO-PET for the first time. This sensitization model will be useful for studying the neurobiology of schizophrenia.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Treatment of seasonal affective disorder with duloxetine: an open-label study

OBJECTIVE

The aim of this observational study was to evaluate the effects of duloxetine in the treatment of seasonal affective disorder (SAD).

PATIENTS AND METHODS

26 SAD patients were treated with open-label duloxetine 60-120 mg per day over 8 weeks. Ratings included the Structured Interview Guide for the Hamilton Depression Rating Scale (SAD version; SIGH-SAD) and the Clinical Global Impression (CGI). To estimate treatment effects on social functioning in SAD we employed the Social Adaptation Self Evaluation Scale (SASS), the Sheehan Disability Scale (SDS), and assessments of days lost due to illness and days with reduction in productivity.

RESULTS

Duloxetine led to a significant improvement (p<0.001) of SIGH-SAD, CGI severity, SASS, and SDS scores. Days lost due to illness and days with reduction in productivity were significantly diminished during treatment (p<0.001). Treatment with duloxetine over 8 weeks yielded a response rate (SIGH-SAD<50% of baseline value) of 80.8% and a remission rate (SIGH-SAD<8) of 76.9% in the intention to treat sample. The drop-out rate due to side effects was 15.4%.

CONCLUSIONS

Our preliminary results indicate that duloxetine might be effective and able to ameliorate the negative social consequences of SAD.

Escitalopram in seasonal affective disorder: results of an open trial

OBJECTIVE

The aim of this study was to evaluate the efficacy and tolerability of escitalopram in the treatment of seasonal affective disorder (SAD, fall-winter depression).

METHODS

Twenty SAD patients were included in an 8-week drug surveillance. Patients were treated with open-label escitalopram at a dosage of 10 to 20 mg per day. Efficacy assessments included the Structured Interview Guide for the Hamilton Depression Rating Scale (SAD version; SIGH-SAD), the Clinical Global Impression (CGI) and the Social Adaptation Self Evaluation Scale (SASS). Side effects were monitored with the UKU Side Effect Rating Scale.

RESULTS

From week 2 onwards, escitalopram significantly reduced SIGH-SAD score and CGI severity score (p<0.001). From week 4 onwards, the SASS score was also significantly improved (p<0.05). The response rate (SIGH-SAD<50% of baseline value) after treatment for 8 weeks was 95%, the rate of remission (SIGH-SAD < or =7) was 85%. Side effects were mild to moderate and did not lead to cessation of therapy.

CONCLUSION

These results suggest that escitalopram is an efficacious and altogether safe treatment for seasonal depression.

A polymorphism (5-HTTLPR) in the serotonin transporter promoter gene is associated with DSM-IV depression subtypes in seasonal affective disorder

Serotonergic mechanisms are thought to play an important role in the pathogenesis of seasonal affective disorder (SAD). The expression of the serotonin transporter (5-HTT) is regulated in part by an insertion/deletion polymorphism in the serotonin transporter gene promoter region (5-HTTLPR). The 5-HTTLPR short allele (s) has been associated with anxiety-related personality traits and depression, and one study observed an association between the 5-HTTLPR s-allele and SAD and the trait of seasonality. We genotyped 138 SAD patients and 146 healthy volunteers with low seasonality for 5-HTTLPR. No difference between patients and controls was found for genotype distribution and s-allele frequency. However, genotype distribution and allele frequencies were strongly associated with DSM-IV depression subtypes. Melancholic depression was associated with the 5-HTTLPR long (l) allele and atypical depression with the 5-HTTLPR s-allele (two-sided Fisher's exact test: genotype distribution: P=0.0038; allele frequencies: P=0.007). Our data are compatible with the hypothesis of a disease process that is not causally related to 5-HTTLPR, but involves 5-HT neurotransmission and 5-HTTLPR somewhere on its way to phenotypic disease expression.

The serotonin transporter promoter repeat length polymorphism, seasonal affective disorder and seasonality

BACKGROUND

Conflicting results have been reported in previous association studies of the serotonin transporter promoter repeat length polymorphism (5-HTTLPR), seasonal affective disorder (SAD) and seasonality (seasonal variations in mood and behaviour). The aim of this study was to test for association in new case-control and population-based materials, and to perform a combined analysis of all published studies of 5-HTTLPR and SAD.

METHOD

One hundred and forty-seven new SAD cases and 115 controls were genotyped for 5-HTTLPR and in total 464 patients and 414 controls were included in the pooled analysis. In addition, 226 individuals selected for unusually high or low seasonality scores from a population based material and 46 patients with non-seasonal depression were analysed. Different genetic models were tested and seasonality was analysed both as a qualitative (high v. low) and as a quantitative trait in the different sample sets.

RESULTS

No association between 5-HTTLPR and SAD was found in the new case-control material, in the combined analysis of all samples, or when only including 316 patients with controls (N = 298) selected for low seasonality. A difference was detected between the population based high and low seasonality groups, when assuming a recessive effect of the short allele (20% and 10% short allele homozygotes, respectively, OR (95% CI): 2.24 (1.03-4.91)). Quantitative analysis of seasonality revealed no association with 5-HTTLPR in any sample set.

CONCLUSIONS

These results do not suggest a major role of the short variant of 5-HTTLPR in susceptibility to SAD, but provide modest evidence for an effect on seasonality.

Evidence for an altered tryptophan metabolism in fibromyalgia

Fibromyalgia (FM) is a prevalent syndrome with chronic pain and a hypothesized underlying disturbance of the tryptophan (TRP) metabolism. We performed a tryptophan depletion (TD) test in 17 FM patients and 17 controls. TRP, 5-hydroxyindoleacetic acid (5-HIAA), kynurenine (KYN), and interleukin-6 (IL-6) were measured. Additionally pain perception was monitored in the FM patients. FM patients and controls exhibited a decrease of TRP and KYN during TD. 5-HIAA levels also decreased in all controls and in 11 FM patients, but showed a marked increase in 6 FM patients. IL-6 significantly increased during TD in the patients, but not in the controls. Pain perception was not affected in the FM patients. These data demonstrate an altered TRP metabolism in a subgroup of FM patients, where the TD seems to activate 5-HT metabolism. Our findings may have diagnostic as well as therapeutic implications in the field of fibromyalgia.

[Seasonal affective depression in 2 German speaking university centers: Bonn, Vienna. Clinical and demographic characteristics]

Six hundred ten patients with seasonal affective disorder (SAD) were diagnosed and treated at the university hospitals for psychiatry in Bonn, Germany (1989-1992) and Vienna, Austria (1993-2001). The aim of this study was to compare our sample with other SAD populations in the literature and to investigate differences between the two study locations. We found female:male sex ratios of 5.0:1.0 in unipolar depressives and 1.5:1.0 in patients with bipolar affective disorder. Of our patients, 21.7% suffered from bipolar II disorder, and 1.3% were diagnosed as having bipolar I. Our patients obtained a mean global seasonality score (GSS) of 15.4. Women had a higher GSS than men (t = 2.127, P = 0.035), and Viennese patients had higher scores than patients in Bonn (t = 3.104, P = 0.002). Totals of 66.3% of all patients suffered from atypical depression and 17.8% from melancholic depression. Patients with atypical depression were more frequent in Vienna, whereas patients with melancholic depression predominated in Bonn (chi 2 = 54.952, df = 2, P < 0.001). The demographic and clinical characteristics of the patients described in this article confirm the findings of other epidemiological investigations obtained in non-German-speaking samples.

Changes of clinical pattern in seasonal affective disorder (SAD) over time in a German-speaking sample

OBJECTIVE

The goals of this study are to provide estimates of clinical and demographic variables of patients with seasonal affective disorder (SAD) in Germany and Austria, to compare our results with those of previously published SAD studies, and to find out whether the clinical pattern of SAD remained stable over several years.

METHOD

We investigated 610 SAD patients from the outpatient clinics in Bonn (n = 190) and Vienna (n = 420). Patients in Bonn were recruited in the fall-winter season of the years 1989-1992, those in Vienna in the years 1993-2001.

RESULTS

We observed a change in the clinical pattern in our patients: patients from Bonn, who were diagnosed and treated about 5 years earlier, were more likely to suffer from melancholic depression, whereas Viennese patients rather suffered from atypical depression (chi(2) = 54.952, df = 2, p < 0.001). The symptoms of hypersomnia, daytime fatigue, increased eating and carbohydrate-craving were more frequent in the Viennese sample, anxiety and deterioration of patients' capacity to perform at work predominated in Bonn. In addition, patients from Vienna obtained a higher GSS (global seasonality score, measured by the SPAQ - Seasonal Pattern Assessment Questionnaire) than those from Bonn (15.7 +/- 3.3 and 14.6 +/- 4.1 respectively; t = 3.104, p = 0.002). Taken together, our results were in good accordance to other published SAD materials, but we were able to demonstrate that our patients reported "feeling worst" (measured by item 13H of the SPAQ) in November and December, whereas SAD patients in the USA clearly had their worst months in January and February.

CONCLUSIONS

We suggest that an increase in awareness of fall-winter depression in the last decade by both doctors, who referred patients, as well as patients or the entire population must have caused patients to sign up for light therapy at the Viennese SAD clinic because of having heard about the atypical symptom profile. This increased awareness of SAD can also be measured by a statistically significant reduction in the diagnostic latency (from the age of onset to the diagnosis of SAD) when comparing the two study locations.

[Pharmacotherapy of seasonal depression]

Seasonal affective disorder (SAD), first described in 1984, is a condition characterized by recurring depressive episodes in fall and winter alternating with nondepressive episodes in spring and summer. Various neurotransmitters have been implicated in the etiology of SAD, with the strongest evidence for an involvement of serotonin. Moreover, researchers have focused on the development of treatment modalities for SAD. Despite the proven efficacy of light therapy in SAD, some patients do not experience sufficient relief of depressive symptoms with light, and a number of them feel unable to comply because of logistical difficulties in administering bright light therapy. Comparatively few studies have examined the role of pharmacotherapy in the treatment of SAD. So far, selective serotonin reuptake inhibitors and possibly compounds with a distinct noradrenergic mechanism of action seem to be the treatment of choice for seasonal depression. There is, however, a clear need for further placebo-controlled studies to evaluate pharmacological treatment options for SAD.

Monoaminergic function in the pathogenesis of seasonal affective disorder

Seasonal affective disorder/winter type (SAD) is characterized by recurrent depressive episodes during autumn and winter alternating with non-depressive episodes during spring and summer. Light therapy with full-spectrum, bright white light has been shown to be effective for this condition. Several hypotheses have been discussed in the literature about the pathogenesis of SAD. The most prominent includes disturbances in central monoaminergic transmission. Evidence can be inferred from studies showing a seasonal rhythm of central and peripheral serotonergic functioning which may be a predisposing factor for SAD. Some of the symptoms of SAD are believed to represent an attempt to overcome a putative deficit in brain serotonergic transmission. Moreover, 5-HT receptor challenge studies suggest altered activity at or downstream to central 5-HT receptors. Monoamine depletion studies support hypotheses about serotonergic and catecholaminergic dysfunctions in SAD and suggest that light therapy may well compensate for this underlying deficit. Further, albeit indirect, support for the importance of monoaminergic mechanisms in SAD and its involvement in the mechanism of the action of light therapy comes from studies showing antidepressant efficacy of serotonergic and noradrenergic antidepressants in the treatment of SAD. Altogether, disturbances in brain monoaminergic transmission seem to play a key role in the pathogenesis of SAD; monoaminergic systems may also play an important role in the mechanisms of the action of light therapy.

Dopamine transporter availability in symptomatic depressed patients with seasonal affective disorder and healthy controls

BACKGROUND

During recent years hypotheses about the pathophysiology of seasonal affective disorder/winter type (SAD) have focused monoaminergic mechanisms. There is substantial evidence that serotonergic systems play an important role. The potential role of catecholaminergic pathways has not been fully explored.

METHODS

Eleven drug-free, symptomatic depressed patients with SAD and 11 healthy age- and gender-matched healthy controls were invited to participate in a 123Ibeta-CIT single photon emission computed tomography (SPECT) study to assess striatal density of dopamine transporters (DATs). The cerebellum was used as reference region. Ratios were calculated between mean counts in left and right striatum and cerebellum. These ratios minus I represent specific/non-displaceable binding and are assumed to be directly related to DAT availability at the time of binding equilibrium.

RESULTS

Displaceable 153Ibeta-CIT binding in the area corresponding to the left striatum was significantly reduced in SAD patients compared to healthy controls (10.49+/-0.91 v. 1195+/-1.54, respectively; 2-tailed P = 0.017, Mann-Whitney U test).

CONCLUSIONS

These data suggest reductions in the availability of striatal DAT binding sites in untreated symptomatic depressed SAD patients. It remains unclear whether these reductions represent a primary defect or an attempt to overcome a state of possible lowered dopamine availability in the synaptic cleft during a depressive episode of SAD. However, these findings provide evidence that brain dopaminergic systems may be involved in the pathophysiology of SAD.

No evidence for in vivo regulation of midbrain serotonin transporter availability by serotonin transporter promoter gene polymorphism

BACKGROUND

A polymorphism in the serotonin transporter promoter gene region (5-HTTLPR) has been shown to influence the quantity of serotonin transporter expressed in human cell lines: the 5-HTTLPR short allele (s) has been associated with reduced 5-HTT expression when compared to cells carrying the 5-HTTLPR long allele (l). We performed a single photon emission computed tomography (SPECT) study using the ligand [(123)I]-2-beta-carbomethoxy-3-beta-(4-iodophenyl)tropane ([(123)I]-beta-CIT) to measure 5-HTT availability in 16 healthy subjects genotyped for 5-HTTLPR.

METHODS

SPECT scans were performed 24 hours after tracer injection, regions of interest anatomically corresponding to the thalamus-hypothalamus and mesencephalon-pons areas were compared to the binding in the cerebellum, representing the nondisplaceable [(123)I]-beta-CIT-binding (results expressed as target activity minus cerebellum activity/cerebellum activity). DNA from peripheral nuclear blood cells was genotyped for 5-HTTLPR using standard polymerase chain reaction methods.

RESULTS

Specific binding ratios in the thalamus-hypothalamus were 2.65 +/- 0.4 in subjects with the l/l genotype (n = 3), 2.76 +/- 0.5 in subjects with the l/s genotype (n = 9), and 2.77 +/- 0.4 in subjects with the s/s genotype (n = 4). Binding ratios in the mesencephalon-pons were 1.43 +/- 0.3 (l/l; n = 3), 1.37 +/- 0.3 (l/s; n = 9), and 1.28 +/- 0.3 (s/s; n = 4). None of these differences was statistically significant.

CONCLUSIONS

Our data provide no evidence for in vivo functional regulation of 5-HTT availability by 5-HTTLPR in the thalamus-hypothalamus and mesencephalon-pons of healthy subjects.

Prevalence of premenstrual dysphoric disorder in female patients with seasonal affective disorder

BACKGROUND

Both seasonal affective disorder/winter type (SAD) and premenstrual dysphoric disorder (PMDD) are cyclical disorders characterized by so-called atypical depressive symptoms. In the present study we compared the point prevalence rates of PMDD between a sample of premenopausal female patients suffering from SAD and healthy female controls.

METHODS

Forty-six female patients with SAD and 46 healthy controls were included in our study. All subjects underwent a semistructured clinical interview according to DSM IV criteria and completed the Seasonal Pattern Assessment Questionnaire. PMDD was diagnosed in a self-rating interview for PMDD according to DSM IV criteria. To verify the diagnosis of PMDD, all patients were followed up in stable summer remission using daily self-rating scales for two full menstrual cycles.

RESULTS

Patients with SAD fulfilled significantly more often the diagnostic criteria for PMDD than female healthy controls (46% vs. 2%, respectively; chi-square: P<0.001).

CONCLUSIONS

These results provide preliminary evidence for a high point prevalence rate of PMDD in premenopausal females with SAD.

CLINICAL IMPLICATIONS

It would be worthwhile to investigate whether an additional diagnosis of PMDD has an impact on the clinical outcome and the response to bright light therapy in female patients with SAD.

[123I] beta-CIT and single photon emission computed tomography reveal reduced brain serotonin transporter availability in bulimia nervosa

BACKGROUND

Impaired serotonin transmission has been implicated in the pathophysiology of eating disorders. We investigated the in vivo availability of brain serotonin transporters and dopamine transporters in bulimia nervosa patients.

METHODS

Approximately 24 hours after injection of [123I]-2beta-carbomethoxy-3beta-(4-iodophenyl)tropane ([123I] beta-CIT), single photon emission computed tomography scans were performed in 10 medication-free, female bulimic patients and 10 age-matched, healthy females. For quantification of brain serotonin transporter and dopamine transporter availability, a ratio of specific to nonspecific [123I] beta-CIT brain binding was used (V(3)" = target region - cerebellum/cerebellum).

RESULTS

Drug-free bulimia nervosa patients showed a 17% reduced brain serotonin transporter availability in the hypothalamus and thalamus, as compared with healthy control subjects (2.4 +/- 0.4 vs. 2.9 +/- 0.4, p =.026), and a similar reduction in striatal dopamine transporter availability. There was a negative correlation of illness duration and serotonin transporter availability (r = -.65; p =.042) and a strong positive correlation between hypothalamic/thalamic and striatal V(3)" (r =.80, p <.001).

CONCLUSIONS

This first report of reduced [123I] beta-CIT binding in a relatively small group of patients with bulimia nervosa suggests a reduced hypothalamic and thalamic serotonin transporter availability in bulimia, which is more pronounced with longer duration of illness.

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.

Monoamine depletion in non-pharmacological treatments for depression

Non-pharmacological treatments such as light therapy for seasonal affective disorder or sleep deprivation for non-seasonal depression have been shown to treat depression effectively. With the use of the tryptophan depletion paradigm and the catecholamine depletion paradigm we assessed the role of brain serotonergic and catecholaminergic systems respectively. We found that disturbances in brain serotonin systems play a key role in the pathogenesis of seasonal affective disorder and that light therapy may compensate for the underlying deficit. Moreover there is evidence that catecholaminergic systems may be involved in the mechanism of action of light therapy. Tryptophan depletion studies suggest that sleep deprivation does not exert its antidepressant effects by involving brain serotonin systems alone. Interestingly, tryptophan depletion prevented the relapse after the recovery night, possibly by enhancing brain serotonin transmission after the depletion procedure.

[123I]-beta-CIT SPECT imaging shows reduced brain serotonin transporter availability in drug-free depressed patients with seasonal affective disorder

BACKGROUND

Numerous findings indicate alterations in brain serotonin systems in seasonal affective disorder (SAD). [(123)I]-2-beta-carbomethoxy-3-beta-(4-iodophenyl)-tropane ([(123)I]-beta-CIT) labels serotonin transporters (5-HTTs) in the midbrain. We performed a [(123)I]-beta-CIT single photon emission computer tomography (SPECT) study under the hypothesis of lower [(123)I]-beta-CIT binding reflecting reduced central 5-HTT availability in depressed SAD patients.

METHODS

Depressed SAD patients and healthy control subjects were investigated using [(123)I]-beta-CIT SPECT 4 hours and again 24 hours after tracer injection. Subjects had either never used psychotropic medication or had been drug-free for at least 6 months prior to the investigation. Specific-to-nondisplaceable partition coefficient (V(3)") was calculated for the thalamus-hypothalamus and the midbrain-pons; the cerebellum served as a reference region.

RESULTS

Patients showed a reduction in V(3)" in thalamus-hypothalamus (2.41+/-0.3 vs. 2.84+/-0.4; p = .026) 24 hours post tracer injection (p.i.). No difference between patients and control subjects was found in midbrain-pons (1.31+/-0.2 vs. 1.42+/-0.2; p = .39). No differences were detected in the SPECT acquisitions 4 hours p.i.

CONCLUSIONS

Depressed SAD patients showed lower specific-to-nondisplaceable [(123)I]-beta-CIT binding in the region of interest (ROI) thalamus-hypothalamus. The small size of the midbrain-pons ROI may have contributed to the failure to show a difference in this ROI as well. Similar to reduced midbrain 5-HTT availability in nonseasonal depression, depression in SAD seems to be associated with reduced 5-HTT availability to the thalamus-hypothalamus.

[Therapeutic sleep deprivation and phototherapy]

Since ancient times the influence of chronobiological factors on the pathogenesis, course, and treatment of depression has been well known. Amongst antidepressive treatment strategies two are based on chronobiological knowledge: therapeutic sleep deprivation, which exerts a rapid and dramatic, albeit usually short-lasting, improvement of mood in the majority of patients with major depressive disorder, and light therapy with full-spectrum bright light. About sixty percent of all depressed patients improve after a single night of total or partial sleep deprivation. It has been shown that a combination of pharmacotherapy with antidepressants and sleep deprivation is superior to pharmacotherapy alone. Moreover, sleep deprivation has proved to hasten the onset of action of antidepressant medication and repeated sleep deprivation can also be an efficient treatment strategy in drug refractory depression. Light therapy with bright artificial light is especially beneficial in patients with a fall/winter pattern of depressive symptomatology that has been termed seasonal affective disorder. Similar to sleep deprivation, bright light therapy is characterized by a fast onset of antidepressant action and by the exertion of additive properties to antidepressive medication. Bright light therapy, beginning in the morning after partial sleep deprivation, is able to prevent the depressive relapse after the next night of sleep in sleep deprivation responders.

Seasonal variation of availability of serotonin transporter binding sites in healthy female subjects as measured by [123I]-2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane and single photon emission computed tomography

BACKGROUND

Previous studies have indicated annual variations in central and peripheral serotonergic activity. In the present study we studied five women in summer and six women in winter and evaluated possible differences in availability of brain serotonin transporters between summer and winter.

METHODS

We employed the single photon emission computed tomography ligand [123I]-2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane ([123I] beta-CIT) to visualize binding to the serotonin transporter site in the human thalamus/hypothalamus midbrain area in vivo. Brain imaging studies were performed in one group between May and August and in the other between November and December.

RESULTS

We found significant differences in displaceable [123I] beta-CIT binding in the region corresponding to thalamus/hypothalamus between the summer group and the winter group (1.9 +/- 0.3 vs. 1.4 +/- 0.2, respectively; p < .01).

CONCLUSIONS

The results of the present study suggest reduced brain serotonin transporter availability in winter. This finding further substantiates evidence of seasonal variations in brain serotonergic function.

Imaging serotonin and dopamine transporters with 123I-beta-CIT SPECT: binding kinetics and effects of normal aging

[123I]beta-carbomethoxy-3-beta-(4-iodophenyl)-tropane (CIT) is a useful ligand for dopamine transporters (DATs) and serotonin transporters (5-HTTs). Previous SPECT studies have shown a state of sustained equilibrium in the striatum on day 2 after injection that allows quantification of striatal DATs using a simple ratio of specific-to-nondisplaceable binding. The aim of this study was to investigate the kinetics of [123I]beta-CIT uptake in the thalamus, hypothalamus, and midbrain, areas known to contain 5-HTTs in high densities.

METHODS

SPECT with a triple-head camera was performed on 16 healthy volunteers (13 women, 3 men; mean age [+/-SD], 32 +/- 11 y) after intravenous bolus injection of 130 +/- 20 MBq (3.5 +/- 0.5 mCi) [123I]beta-CIT. Two individuals were scanned 1, 2, 4, 7, 10, 13, 16, and 24 h after injection, and the remaining 14 were scanned 4, 7, 10, 20, and 24 h after injection. Values from 19 previously examined healthy volunteers (8 women, 11 men; mean age, 52 +/- 20 y) were included in the analysis to study the age dependency of beta-CIT binding in striatal and 5-HTT-rich brain areas in a larger control sample.

RESULTS

Peak uptake 4 h after injection, followed by stable uptake until 10 h and a slow decrease until 24 h, was observed in the thalamus-hypothalamus region. Activity in the midbrain-pons region peaked 2 h after injection. Because of a concomitant slow but steady decline of uptake in reference regions starting 4 h after injection, a higher stability of binding ratios for 5-HTT-rich brain areas was observed on day 2, suggesting that a state of transient equilibrium is reached between 20 and 24 h but that conditions are only close to transient equilibrium between 4 and 10 h after injection for 5-HTT-rich brain areas. In addition to an age-related decline of striatal [123I]beta-CIT binding of 6.6% per decade, a significant age-associated decrease of beta-CIT binding of 3-4% per decade was found in 5-HTT-rich brain areas. The decline of beta-CIT binding in these regions may be explained, at least in part, by a loss of monoamine transporters with age but may also be related to age-associated morphologic changes.

CONCLUSION

[123I]beta-CIT appears to be a suitable ligand for imaging serotonin transporters with SPECT. However, careful age matching is warranted for [123I]beta-CIT SPECT studies of 5-HTT changes in patients with neuropsychiatric disorders.

Tryptophan depletion: a predictor of future depressive episodes in seasonal affective disorder?

Patients with seasonal affective disorder (SAD) do not necessarily experience depressive episodes every winter. We assessed whether the behavioural response to tryptophan depletion in summer when patients are fully remitted and off therapy is capable of predicting a future depressive episode of SAD. In a prospective study design, we followed up 11 consenting SAD patients who had undergone tryptophan depletion during summer. We evaluated how many of these patients would develop a depressive episode in the subsequent fall/winter. Seven out of eight patients who relapsed during tryptophan depletion in summer developed a depressive episode in the subsequent winter. Two out of the three patients who did not relapse during tryptophan depletion remained well during the follow-up period. Our preliminary findings suggest that those SAD patients who develop depressive symptoms during tryptophan depletion when they are fully remitted and off therapy remain at high risk to experience a depressive episode of SAD also in the subsequent winter.

Behavioral effects of tryptophan depletion in seasonal affective disorder associated with the serotonin transporter gene?

There is some evidence that the neurotransmitter serotonin (5-hydroxytryptamine; 5-HT) may be involved in the pathogenesis of seasonal affective disorder (SAD). Short-term tryptophan (TRP) depletion was carried out in 18 drug-free remitted patients who met DSM-IV criteria for SAD. Behavioral effects were measured with the Hamilton Depression Rating Scale (HDRS) both 24 h before and 24 h after TRP depletion. Some of the patients showed behavioral responses such as lowered mood, feelings of guilt, loss of interest, agitation, loss of energy, fatigue, social withdrawal, increased appetite, and carbohydrate craving. It was the aim of our study to investigate whether the genotypes of the serotonin transporter gene were associated with symptoms of transient depressive relapse after TRP depletion. In addition, we matched the SAD patients with healthy control subjects to see if alleles and genotypes of the serotonin transporter gene were associated with SAD. High molecular weight DNA was isolated from peripheral blood leukocytes using standard methods. For the 5-HTT receptor gene, a 17-bp repetitive element of intron 2 was genotyped (variable number tandem repeat, VNTR). Alterations in HDRS scores after TRP depletion showed no significant association with alleles or genotypes of the 5-HTT gene, although heterozygotes showed a trend toward increased HDRS scores. The serotonin transporter is known to play a critical role in the termination of serotonergic neurotransmission by sodium-dependent uptake of 5-HT into the presynaptic neuron. The present study in a small group of SAD patients was unable to demonstrate that the 5-HTT gene plays a role in the pathogenesis of SAD or in short-term depressive relapse after TRP depletion.

[Mirtazapine in inpatient treatment of depressed patients]

Mirtazapine is a new antidepressant with a specific pharmacological profile which is different from all other currently available antidepressants. It is a so-called noradrenergic and specific serotonergic antidepressant (NaSSA). 46 in-patients were treated with mirtazapine. The mean dose was 56 mg mirtazapine per day (SD: 23; range: 15 to 90). The duration of treatment was 3.6 weeks (SD +/- 3.4). Patients presented with following diagnosis: 29 (= 63%) were diagnosed as having a unipolar depression, 26% (n = 12) suffered from a depression in the course of a bipolar disorder. 37% (n = 17) were moderately depressed, 52% (n = 24) were severely depressed. 2 patients (= 4%) met ICD-10 (international Classification of Diseases) criteria for a schizoaffective disorder, 2 patients (= 4%) suffered from dysthymia. 1 patient suffered from an organic depressive disorder. The efficacy of the treatment was evaluated with CGI (Clinical Global Impression), when patients were discharged from hospital. 68% of the patients were in partial or full remission (CGI 2, 3 and 4), 17% were unimproved (CGI 5 and 6), in 15% of the patients the treatment was stopped before. Our observations are indicative that mirtazapine is effective in the treatment of moderately and severely depressed patients and therefore confirm the data obtained in phase III-trials. Furthermore we found mirtazapine in either mono- or combination-therapy with various other antidepressants to be tolerated well. Side effects did not cause in a single patient a discontinuation in treatment.

Effects of tryptophan depletion in fully remitted patients with seasonal affective disorder during summer

BACKGROUND

Deficiencies in brain serotonin function are believed to play an important role in the pathophysiology of seasonal affective disorder/winter type (SAD). However, no direct evidence has been reported so far that lowered brain serotonin activity causes the symptoms of SAD.

METHODS

We studied 11 SAD patients who had suffered recurrent winter depressive episodes of SAD and were fully recovered and off treatment during the summer. In a randomized, balanced, double-blind crossover design patients received two amino acid beverages, one containing tryptophan and the other containing no tryptophan but otherwise identical. Behavioural ratings and plasma total and free tryptophan concentrations were assessed at baseline before administration of the amino acid beverages and at several time points afterwards.

RESULTS

The tryptophan-free amino acid beverage induced significant decreases of plasma total and free tryptophan levels and both levels increased during sham depletion (condition x time interaction: P < 0.001). Tryptophan depletion, but not sham depletion caused a transient return of depressive symptoms (condition x time interaction: P < 0.001).

CONCLUSIONS

The present study demonstrates that SAD patients in remission during the summer are vulnerable to a return of depression when depleted of tryptophan. This finding supports the importance of serotonergic mechanisms in the pathophysiology of SAD.

Effects of tryptophan depletion in drug-free depressed patients who responded to total sleep deprivation

BACKGROUND

There is some evidence that sleep deprivation (SD) might exert its antidepressant properties by involving serotonergic mechanisms. We investigated the effects of short-term tryptophan depletion (TD) on depressed patients who responded to a single night of total SD.

METHODS

Drug-free depressed inpatients (n = 30) were randomly assigned to either TD or sham depletion. Tryptophan depletion was induced by a 24-hour low-tryptophan diet (day 1) followed the next morning by ingestion of a tryptophan-free amino acid mixture (day 2). During sham depletion, the diet and the amino acid beverage were supplemented with tryptophan. Sleep deprivation was performed from day 1 until day 2. Only SD responders received the amino acid beverage the morning after SD. Behavioral ratings and total and free plasma tryptophan levels were obtained before and after the test sessions.

RESULTS

Twenty-two of 30 patients showed a favorable outcome after SD. As predicted, TD significantly lowered total and free plasma tryptophan levels, whereas both levels increased during sham depletion. No acute effects on mood were observed during the day after SD in either treatment group. Unexpectedly, TD, but not control testing, prevented the depressive relapse after the recovery night in most of the patients.

CONCLUSIONS

Tryptophan depletion did not reverse the antidepressant effects of SD, but it prevented the relapse beyond a night of recovery sleep. These findings suggest that SD does not act via a single monoamine-related mechanism, but they allow the assumption that TD may induce neurochemical alterations that transiently improve depression.

A risk-benefit assessment of mirtazapine in the treatment of depression

Mirtazapine is the first of a new class of antidepressants, the noradrenergic and specific serotonergic antidepressants (NaSSA). Its antidepressant effect appears to be related to its dual enhancement of central noradrenergic and serotonin 5-HT1 receptor-mediated serotonergic neurotransmission. Mirtazapine possesses a number of useful pharmacokinetic characteristics such as good absorption, linear pharmacokinetics over the recommended dosage range (15 to 80 mg/day), and an elimination half-life of 20 to 40 hours, thereby allowing once-daily administration. However, since the drug is extensively metabolised by the hepatic cytochrome P450 (CYP) system and is excreted mainly in the urine, its clearance may be reduced by hepatic or renal impairment. In vitro data suggest that from a clinical point of view it is unlikely that mirtazapine would inhibit the metabolism of coadministered drugs metabolised by CYP1A2, CYP2D6 or CYP3A4. In vivo data from a study in extensive and poor metabolisers of debrisoquine indicate that strong inhibitors of CYP2D6 would have no effect on the concentration of racemic mirtazapine. In some placebo-controlled studies mirtazapine showed an early onset of antidepressant action, with significant reductions in total Hamilton Depression Rating Scale and Montgomery-Asberg Depression Rating Scale scores (relative to placebo) noted as early as 1 week after starting treatment. This therapeutic advantage was subsequently maintained during treatment, with mirtazapine proving significantly superior to placebo at treatment end-point in the majority of studies. In comparative trials, the antidepressant efficacy of mirtazapine was comparable with that of tricyclic antidepressants such as amitriptyline, clomipramine and doxepin, and in 2 studies superior to that of trazodone and fluoxetine. Mirtazapine appears to have a broad spectrum of activity, reflected in its efficacy in a variety of clinical settings. Its additional beneficial effects on the symptoms of anxiety and sleep disturbance associated with depression may reduce the need for concomitant anxiolytic and hypnotic medication seen with some antidepressants. Mirtazapine has demonstrated superior tolerability to the tricyclic antidepressants and trazodone, primarily on account of its relative absence of anticholinergic, adrenergic and serotonin-related adverse effects, in particular gastrointestinal adverse effects and sexual dysfunction. It appears that increased sedation associated with the drug is related to subtherapeutic dosages, and that it is reported in substantially fewer patients when the drug is used in appropriate dosages (> or = 15 mg as a single evening dose) from the beginning of treatment. Although 2 cases of reversible severe symptomatic neutropenia have been reported in clinical trials, there have been no additional reports of symptomatic neutropenia since the introduction of this drug to various countries in September 1994. Currently available data and initial clinical experience suggest that with its combination of dual action, simple pharmacokinetics, and clinical efficacy and tolerability, mirtazapine appears to be an important advance in the pharmacotherapy of depression.

Suicidal tendencies as a complication of light therapy for seasonal affective disorder: a report of three cases

BACKGROUND

Suicidality in seasonal affective disorder (SAD) subjects treated with bright light therapy seems to be a rare phenomenon. We report on three SAD patients with predominant atypical symptoms who presented for treatment in our clinic for SAD. Two suffered from bipolar disorder, one from recurrent major depressive disorder.

METHOD

All subjects were drug-free and treated with bright light therapy as a monotherapy for the first time. Treatment response was assessed weekly by standardized rating instruments, using the Hamilton Rating Scale for Depression (HAM-D) and the HAM-D-SAD addendum for assessment of atypical symptoms.

RESULTS

Within the first week after beginning bright light therapy, two subjects attempted suicide. The third patient developed suicidal thoughts that were so acute and overwhelming that we had to discontinue bright light therapy and start with psychopharmacologic treatment in an inpatient setting.

CONCLUSION

It is suggested that bright light-induced amelioration of drive and mood can be dissociated as can be the case in the "critical time" of antidepressant therapy. The authors believe the collection of prevalence data on suicide and SAD would be worthwhile.

Rapid tryptophan depletion in drug-free depressed patients with seasonal affective disorder

OBJECTIVE

Brain serotonin systems might be involved in the pathophysiology of seasonal affective disorder. The authors tested whether tryptophan depletion alters the mood of depressed patients with seasonal affective disorder.

METHOD

Eleven drug-free depressed patients with seasonal affective disorder underwent tryptophan depletion in a placebo-controlled, double-blind crossover study. Tryptophan depletion was induced by a 24-hour low-tryptophan diet and by ingestion of a tryptophan-free amino acid beverage. During control testing the diet and the beverage were supplemented with tryptophan. Behavioral ratings and plasma total and free tryptophan levels were obtained before the diet started and several times after administration of the beverages.

RESULTS

The diet and the tryptophan-free amino acid drink reduced plasma total and free tryptophan levels by 79.0% and 87.5%, respectively. Both levels increased during control testing. No significant behavioral changes were induced by tryptophan depletion or control testing.

CONCLUSIONS

The failure of tryptophan depletion to exacerbate the depressive syndrome suggests that dysfunctional serotonergic activity does not play a primary, direct role in the pathogenesis of winter depression.

[The tryptophan depletion test. Basic principles and clinical relevance]

The application of a tryptophan-free amino acid mixture (tryptophan depletion test) induces a rapid and substantial lowering of both total and free plasma tryptophan. Consequently, the brain serotonin content and also cerebral serotonin function are decreased. This method provides a paradigm to study the role of serotonin in the pathobiology of depressive disorders and their treatment modalities. Untreated depressed patients show few behavioral effects during tryptophan depletion. In depressed patients during an antidepressant or light-therapy-induced stable remission, a transient depressive relapse was induced by tryptophan depletion. Healthy subjects with a genetic risk for affective disorder show worsening of their condition induced by tryptophan depletion. These findings indicate the relevance of altered brain serotonin function in the pathophysiology of affective disorders and strengthen the importance of serotonin in the mechanism of action of antidepressants. Since recently published studies revealed some evidence that the serotonergic system is directly involved in the pathophysiology of various psychiatric syndromes besides depression, it seems to be reasonable to evaluate the validity of the tryptophan depletion test also in non-depressed patients.

Effects of tryptophan depletion on drug-free patients with seasonal affective disorder during a stable response to bright light therapy

BACKGROUND

A dysfunction of the serotonin system may play a major role in the pathogenesis of seasonal affective disorder. Bright light therapy has been shown to be effective in the treatment of winter depression in patients with seasonal affective disorder. Light therapy-induced remission from depression may be associated with changes in brain serotonin function.

METHODS

After at least 2 weeks of clinical remission, 12 drug-free patients who had had depression with seasonal affective disorder underwent tryptophan depletion in a double-blind, placebo-controlled, balanced cross-over design study.

RESULTS

Short-term tryptophan depletion induced a significant decrease in plasma free and total tryptophan levels (P < .001 for both, repeated measures analysis of variance), with peak effects occurring 5 hours after ingestion of a tryptophan-free amino acid drink. It emerged that tryptophan depletion leads to a transient depressive relapse, which was most pronounced on the day after the tryptophan-depletion testing. No clinically relevant mood changes were observed in the control testing.

CONCLUSIONS

The maintenance of light therapy-induced remission from depression in patients with seasonal mood cycles seems to depend on the functional integrity of the brain serotonin system. Our results suggest that the serotonin system might be involved in the mechanism of action of light therapy.