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 D2/3 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.

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.

[Seasonal affective depression in 2 German speaking university centers: Bonn, Vienna. Clinical and demographic characteristics]. / Saisonal abhängige Depression in zwei deutschsprachigen Universitätszentren: Bonn, Wien. Klinische und demographische Charakteristika.

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]. / Die Pharmakotherapie der saisonal abhängigen 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.

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.

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.

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.

[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.

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.

UNLABELLED: [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.