Seasonal affective disorder: response to light as measured by electroencephalogram, melatonin suppression, and cerebral blood flow

Stable abnormalities of contrast discrimination sensitivity in subthreshold depression: A longitudinal study

Subthreshold depression (StD), as a subclinical state, is highly prevalent and increases the risk for developing major depressive disorder (MDD). Although several studies have reported deficits of contrast sensitivity in MDD patients, it is unclear whether individuals with StD could demonstrate deficits of contrast sensitivity and whether the deficits could remain stable over time. Here we used a contrast discrimination task (a suprathreshold task) and a contrast detection task (a near-threshold task) to compare contrast sensitivity of the StD group with that of matched non-depressed controls. For each task, a spatial four-alternative forced-choice method and a psychophysical QUEST procedure were used to measure contrast discrimination threshold or contrast detection threshold. Participants performed an initial assessment and a follow-up assessment 4 months later. Compared to the non-depressed controls, individuals with StD demonstrated reduced contrast discrimination sensitivity, not only at the initial assessment but also at the follow-up assessment, indicating a stable abnormality. Contrast discrimination thresholds at the initial assessment did not predict changes of depression symptom severity over time. For contrast detection sensitivity, there was no significant difference between the StD group and non-depressed controls. We concluded that contrast discrimination testing might provide a trait-dependent biomarker for depression.

Increased sensitivity to light-induced melatonin suppression in premenstrual dysphoric disorder

Increased sensitivity to light-induced melatonin suppression characterizes some, but not all, patients with bipolar illness or seasonal affective disorder. The aim of this study was to test the hypothesis that patients with premenstrual dysphoric disorder (PMDD), categorized as a depressive disorder in Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), have altered sensitivity to 200 lux light during mid-follicular (MF) and late-luteal (LL) menstrual cycle phases compared with normal control (NC) women. As an extension of a pilot study in which the authors administered 500 lux to 8 PMDD and 5 NC subjects, in the present study the authors administered 200 lux to 10 PMDD and 13 NC subjects during MF and LL menstrual cycle phases. Subjects were admitted to the General Clinical Research Center (GCRC) in dim light (<50 lux) to dark (during sleep) conditions at 16:00 h where nurses inserted an intravenous catheter at 17:00 h and collected plasma samples for melatonin at 30-min intervals from 18:00 to 10:00 h, including between 00:00 and 01:00 h for baseline values, between 01:30 and 03:00 h during the 200 lux light exposure administered from 01:00 to 03:00 h, and at 03:30 and 04:00 h after the light exposure. Median % melatonin suppression was significantly greater in PMDD (30.8%) versus NC (-0.2%) women (p = .040), and was significantly greater in PMDD in the MF (30.8%) than in the LL (-0.15%) phase (p = .047). Additionally, in the LL (but not the MF) phase, % suppression after 200 lux light was significantly positively correlated with serum estradiol level (p = .007) in PMDD patients, but not in NC subjects (p > .05).

Less Exposure to Daily Ambient Light in Winter Increases Sensitivity of Melatonin to Light Suppression

This study was carried out to examine the seasonal difference in the magnitude of the suppression of melatonin secretion induced by exposure to light in the late evening. The study was carried out in Akita (39 degrees North, 140 degrees East), in the northern part of Japan, where the duration of sunshine in winter is the shortest. Ten healthy male university students (mean age: 21.9+/-1.2 yrs) volunteered to participate twice in the study in winter (from January to February) and summer (from June to July) 2004. According to Japanese meteorological data, the duration of sunshine in Akita in the winter (50.5 h/month) is approximately one-third of that in summer (159.7 h/month). Beginning one week prior to the start of the experiment, the level of daily ambient light to which each subject was exposed was recorded every minute using a small light sensor that was attached to the subject's wrist. In the first experiment, saliva samples were collected every hour over a period of 24 h in a dark experimental room (<15 lux) to determine peak salivary melatonin concentration. The second experiment was conducted after the first experiment to determine the percentage of melatonin suppression induced by exposure to light. The starting time of exposure to light was set 2 h before the time of peak salivary melatonin concentration detected in the first experiment. The subjects were exposed to light (1000 lux) for 2 h using white fluorescent lamps (4200 K). The percentage of suppression of melatonin by light was calculated on the basis of the melatonin concentration determined before the start of exposure to light. The percentage of suppression of melatonin 2 h after the start of exposure to light was significantly greater in winter (66.6+/-18.4%) than summer (37.2+/-33.2%), p<0.01). The integrated level of daily ambient light from rising time to bedtime in summer was approximately twice that in winter. The results suggest that the increase in suppression of melatonin by light in winter is caused by less exposure to daily ambient light.

A missense variant (P10L) of the melanopsin (OPN4) gene in seasonal affective disorder

BACKGROUND

Melanopsin, a non-visual photopigment, may play a role in aberrant responses to low winter light levels in Seasonal Affective Disorder (SAD). We hypothesize that functional sequence variation in the melanopsin gene could contribute to increasing the light needed for normal functioning during winter in SAD.

METHODS

Associations between alleles, genotypes, and haplotypes of melanopsin in SAD participants (n=130) were performed relative to controls with no history of psychopathology (n=90).

RESULTS

SAD participants had a higher frequency of the homozygous minor genotype (T/T) for the missense variant rs2675703 (P10L) than controls, compared to the combined frequencies of C/C and C/T. Individuals with the T/T genotype were 5.6 times more likely to be in the SAD group than the control group, and all 7 (5%) of individuals with the T/T genotype at P10L were in the SAD group.

LIMITATIONS

The study examined only one molecular component of the non-visual light input pathway, and recruitment methods for the comparison groups differed.

CONCLUSION

These findings support the hypothesis that melanopsin variants may predispose some individuals to SAD. Characterizing the genetic basis for deficits in the non-visual light input pathway has the potential to define mechanisms underlying the pathological response to light in SAD, which may improve treatment.

Diminished perception of light as a symptom of depression: further studies

BACKGROUND

In a previous preliminary report, the perception of a decrease in ambient light intensity appeared to be correlated with depression. We prospectively studied this potential link in a controlled study.

METHODS

The question, "I've noticed that the lights in my surroundings seem dimmer than usual", was added to the Center for Epidemiologic Studies Depression Scale (CES-D) questionnaire and administered prospectively to 213 subjects 50-80 years of age participating in the Age-Related Eye Disease Study (AREDS). All had visual acuity of 20/32 or better in at least one eye. Main outcome measures were the relationship between the dimness question answer and severity of depression, and the likelihood that patients reporting dimness were depressed.

RESULTS

Subjects endorsing their surroundings as being dimmer than usual at least some of the time had a mean CES-D score of 10.6 (SD=7.0) compared to a mean of 5.5 (SD=5.4) for subjects who never noted dimness (t=-4.22, p=.0001). Depressed individuals (CES-D > or = 16) were significantly more likely to report dimness than non-depressed (CES-D<16) subjects (chi(2)=15.6, p<0.0001). The total CES-D score and the degree of reported dimness (0-3) were significantly associated (r=0.31, p<.0001). Using a stepwise regression analysis, subjects who reported any dimness were more likely to be depressed.

LIMITATIONS

A relatively small number of subjects, 38 (18%), reported dimness requiring us to dichotomize their dimness level in some analyses.

CONCLUSIONS

Perceived dimness of one's ambient surroundings and clinical depression are linked. Health care professionals should inquire about this symptom in potentially depressed patients.

Pituitary volume and the effects of phototherapy in patients with seasonal winter depression: a controlled study

OBJECTIVES: Our aims were to investigate the pituitary volume in patients with seasonal winter depression and healthy volunteers in winter and summer, and to assess the effects of phototherapy in these patients. METHOD: The pituitary volume of 12 patients with winter depression and 12 healthy controls, paired according gender, age and menstrual cycle, were obtained from magnetic resonance imaging in winter and summer. Eight patients were submitted to phototherapy (10000 vs. 2500 lux) in a double-blind crossover fashion during the winter, and reassessed (symptoms and magnetic resonance imaging) after treatment. RESULTS: There were no significant differences in pituitary volume between controls and patients in winter or summer. Exposure to phototherapy (10000 lux) decreased the depressive symptoms (p = 0.004), but the glandular volume did not change (p = 0.5). However, the pituitary volume in winter showed a positive correlation with the severity of depression in these patients (r = 0.69, p = 0.04). CONCLUSIONS: The results suggest that neither winter depression nor the change of seasons is associated with significant change in the pituitary volume. Despite the fact that this study was performed in a tropical area, phototherapy with 10000 lux showed to be an efficient treatment in this SAD patients sample.

Melatonin Administration Acutely Decreases the Diffusing Capacity of Carbon Monoxide in Human Lungs

BACKGROUND

Most physiological measurements of the pulmonary diffusing capacity use carbon monoxide (CO) as a tracer gas. Similar to CO, melatonin binds the hemoglobin in the blood.

OBJECTIVE

The present study was designed to assess the effect of exogenous melatonin administration on pulmonary functions including diffusing capacity for carbon monoxide (DL(CO)) in healthy subjects.

METHODS

The study was performed in a randomized, double-blind, placebo-controlled manner. DL(CO) was measured in 22 healthy male volunteers (age 18-25 years) who were randomized to melatonin (n = 11) and placebo administration (n = 11). At baseline, DL(CO), alveolar volume (V(A)) and other spirometric parameters such as forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC), peak expiratory flow (PEF) and maximal voluntary ventilation (MVV) were measured. DL(CO) was then corrected for the hemoglobin concentration. Measurements were repeated in a double-blind fashion 60 min after the administration of melatonin (1 mg) or placebo.

RESULTS

DL(CO) was significantly decreased (39.31 +/- 4.75 vs. 34.82 +/- 6.18 ml/min/mm Hg) 60 min after the melatonin administration (p = 0.01), while FEV(1), FVC, FEV(1)/FVC, PEF and MVV values did not demonstrate significant differences. Placebo administration did not result in significant alteration in any of these parameters.

CONCLUSIONS

In healthy subjects, oral administration of melatonin acutely influences the DL(CO) without affecting other pulmonary function test results. We conclude that melatonin may have a reducing effect on the DL(CO) in the lungs.

Light therapy increases visual contrast sensitivity in seasonal affective disorder

The purpose of this study was to investigate the effects of light therapy on visual contrast sensitivity in patients with seasonal affective disorder (n=10) and healthy control subjects (n=10). Static and dynamic visual contrast sensitivity was measured using a Venus system before and after 4 weeks of light therapy (10,000 lux, 30 min, 5 times a week). Light therapy increased static visual contrast sensitivity in the patients. We found no significant difference between the patients and controls either before or after light therapy. These results raise the possibility that light therapy induces retinal sensitization in seasonal affective disorder.

Seasonal affective disorder: an overview

Seasonal Affective Disorder (SAD) is a condition of regularly occurring depressions in winter with a remission the following spring or summer. In addition to depressed mood, the patients tend to experience increased appetite and an increased duration of sleep during the winter. SAD is a relatively common condition, affecting 1-3% of adults in temperate climates, and it is more prevalent in women. The pathological mechanisms underlying SAD are incompletely understood. Certain neurotransmitters have been implicated; a dysfunction in the serotonin system in particular has been demonstrated by a variety of approaches. The role of circadian rhythms in SAD needs to be clarified. The phase-delay hypothesis holds that SAD patients' circadian rhythms are delayed relative to the sleep/wake or rest/activity cycle. This hypothesis predicts that the symptoms of SAD will improve if the circadian rhythms can be phase-advanced. There is some experimental support for this. SAD can be treated successfully with light therapy. In classical light therapy, the SAD sufferer sits in front of a light box, exposed to 2000-10,000 lux for 30-120 min daily during the winter. Other forms of light treatments, pharmacotherapy, and other therapies are currently being tested for SAD.

The effects of prior light history on the suppression of melatonin by light in humans

We investigated the impact of light exposure history on light sensitivity in humans, as assessed by the magnitude of the suppression of melatonin secretion by nocturnal light. The hypothesis was that following a week of increased daytime bright-light exposure, subjects would become less sensitive to light, and that after a week of restriction to dimmer light they would become more sensitive. During the bright week, subjects (n = 12) obtained 4.3 +/- 0.4 hr of bright light per day (by going outside and using light boxes indoors). During the dim week, they wore dark goggles (about 2% light transmission) when outside during daylight and spent 1.4 +/- 0.9 hr per day outside. Saliva samples were obtained every 30 min for 7 hr in dim light (<15 lux) on two consecutive nights (baseline and test night) at the end of each week. On the test night, 500 lux was presented for 3 hr in the middle of the collection period to suppress melatonin. There was significantly more suppression after the dim week compared with after the bright week (to 53 versus 41% of the baseline night values, P < 0.05). However, there were large individual differences, and the difference between the bright and dim weeks was most pronounced in seven of the 12 subjects. Possible reasons for these individual differences are discussed, including the possibility that 1 wk was not long enough to change light sensitivity in some subjects. In conclusion, this study suggests that the circadian system's sensitivity to light can be affected by a recent change in light history.

EEG mapping in seasonal affective disorder

Given that the nature of hemispheric dysfunction is different in heterogeneous disorders, in the present investigation EEG power mapping was applied to establish neurophysiological profiles that might potentially discriminate patients with seasonal affective disorder (SAD) among other affective disorders. The baseline resting EEG activity was recorded from 31 depressed SAD patients and 30 controls. Power in the delta, theta-1, theta-2, alpha, beta-1 and beta-2 frequency bands was extracted by Fourier transformation. Patients were found to have a lower delta (in central, parietal, occipital, temporal, posterior-temporal areas), theta-1 (in central and parietal), theta-2 (in anterior-frontal, parietal, occipital) and alpha activity (in anterior-frontal, midfrontal, central, parietal and occipital areas) than controls. SAD subjects showed, compared to controls, an asymmetrical distribution of delta, theta-1, theta-2 and alpha activity in parietal and temporal regions due to an increase of EEG power over the right electrode sites, and beta activity in the lateral frontal region due to an increase of beta power over the right electrode site. It is assumed that differential hemispheric contributions of EEG spectra may discriminate between the varieties of depression or different depressive states.

Seasonal affective disorder: spatial organization of EEG power and coherence in the depressive state and in light-induced and summer remission

The present study analyzed EEG power and coherence in subjects with seasonal affective disorder (SAD) during depressive episodes and during light-induced and summer remission. Baseline EEG activity was recorded during the winter period before light treatment (31 SAD patients, 30 control subjects); after 10 days of 2-h morning light treatment (10 SAD subjects); and during the summer period (14 SAD subjects, 27 control subjects). EEG power and coherence were calculated for the delta, theta-1, theta-2, alpha, beta-1 and beta-2 frequency bands. Compared with control subjects, SAD subjects had lower than normal EEG power in most frequency bands; asymmetrical distribution of delta, theta-1, theta-2 and alpha activity in parietal and temporal regions due to increased EEG power over the left electrode sites; and beta activity in the lateral frontal region due to increased beta power over the right electrode site. The foci of decreased EEG coherence were mainly in the right and left frontal and the right posterior regions. Remitted SAD subjects showed normalization of inter-hemispheric asymmetry in lateral frontal areas; increases of delta, theta-2, and alpha activity compared with control values; theta-1 activity in excess of control values; and disappearance of the foci of decreased coherence in anterior areas of the left hemisphere.

Diminished perception of ambient light: a symptom of clinical depression?

OBJECTIVE

In a non-randomized, uncontrolled pilot study, the authors investigated whether depressed patients were more likely to perceive the lighting in their environment as being dimmer than usual.

METHOD

120 patients (46 males, 74 females) who presented for possible admission for depression at a psychiatric facility were administered a Diagnostic and Statistical Manual of disorders (DSM-IV) based questionnaire and underwent psychiatric evaluation. A question asking whether 'the lights in my surroundings seem dimmer than usual' was included in the 15-point question survey. Statistical analyses were performed to determine whether an affirmative response to this dimness question was correlated with the depth of depression (mild, moderate, severe) and also whether significant correlation was present between the percentage of patients answering yes to the dimness question versus the number of yes responses to the core symptoms of depression.

RESULTS

Two thirds of the patients categorized as severely depressed responded that their ambient environment appeared dimmer than usual compared to 21% of moderately and 14% of mildly depressed patients. This difference was statistically significant (P<0.05). The degree of depression as determined by the number of core questions answered affirmatively and the presence of this 'dimness' symptom were highly correlated (P=0.002, R=0.87).

LIMITATIONS

The specificity of the finding has not been tested in reference to non-affective psychiatric patient groups.

CONCLUSION

A patient's perception of the ambient light in the environment being dimmer than usual may be an important symptom of a major depressive disorder. Further replication and objective testing of visual function in depressed patients appears warranted.

Winter and summer outdoor light exposure in women with and without seasonal affective disorder

BACKGROUND

The annual decrease of daylight duration initiates a depressive phase in patients with seasonal affective disorder (SAD), and light therapy treats it. How much bright light exposure in winter and summer these patients actually receive may help understand the pathogenetic factors initiating SAD.

METHODS

During a week in winter and summer, women with and without SAD kept daily logs of the time spent outdoors, subjective sleep, and self-ratings of mood and alertness.

RESULTS

Compared with the winter depressive state, mood, alertness, and sleep of SAD patients improved in summer to control values, but did not correlate with the amount of light exposure. In summer, patients with SAD spent more time outdoors than controls.

LIMITATION

Light logs--in comparison with light monitor measurements--may overestimate light exposure outdoors.

CONCLUSION

Women with SAD do not spend less time outdoors in winter than controls, but spend more time outdoors in summer.

CLINICAL RELEVANCE

Patients with SAD show a high amplitude seasonal difference in outdoor light exposure. The susceptibility to winter depression may arise not from behaviourally-related lack of sufficient light exposure, but an increased vulnerability to the amount of light received. They may require more light than controls to remain euthymic (higher light exposure in summer, light therapy in winter).

Can winter depression be prevented by Ginkgo biloba extract? A placebo-controlled trial

OBJECTIVE

The aim was to test the hypothesis that the Ginkgo biloba extract PN246, in tablet form (brand name Bio-Biloba), may prevent the symptoms of winter depression (WD) in patients with seasonal affective disorder (SAD).

METHOD

A total of 27 SAD patients were randomized to receive double-blind placebo or Bio-Biloba for 10 weeks or until they developed symptoms of WD, starting in a symptom-free phase about 1 month before expected WD symptoms. An extended Montgomery-Asberg Depression Rating Scale was completed before and immediately after termination of medication. The patients also self-rated some key symptoms on a visual analogue scale every 2 weeks during the trial.

RESULTS

There were no significant differences between the treatment groups in the number of patients who developed treatment-requiring WD, or in the development of single key symptoms during the trial.

CONCLUSION

We did not find that Ginkgo biloba was able to prevent the development of the symptoms of winter depression.

Seasonal affective disorder

Seasonal affective disorder (SAD) is a form of recurrent depressive or bipolar disorder, with episodes that vary in severity. Seasonal patterns of depressive episodes are common, but SAD seems to be less common than such patterns suggest. SAD was at first believed to be related to abnormal melatonin metabolism, but later findings did not support this hypothesis. Studies of brain serotonin function support the hypothesis of disturbed activity. The short-allele polymorphism for serotonin transporter is more common in patients with SAD than in healthy people. Atypical depressive symptoms commonly precede impaired functioning, and somatic symptoms are frequently the presenting complaint at visits to family physicians. The best treatment regimens include 2500 Ix of artificial light exposure in the morning. When patients seem to have no response or to prefer another treatment, antidepressants should be considered.

Alzheimer's disease risk factors as related to cerebral blood flow: additional evidence

In a previous report, Alzheimer's disease risk factors, including alcohol abuse, depression, Down's syndrome, cerebral glucose metabolism defect, head trauma, old age, Parkinson's disease, sleep disturbance, and underactivity, were shown to have an association with reduced cerebral blood flow. In this report an attempt is made to strengthen a hypothesis that reduced cerebral blood flow may be a required cofactor in the cause of Alzheimer's disease with examples of additional putative risks, including aluminum, ApoE 4 alleles, estrogen deficiency, family history of dementia, low education-attainment, olfactory deficit, and underactivity coupled with gender, considered to have a relationship or potential relationship with reduced cerebral blood flow. Factors, believed to ameliorate Alzheimer's disease, associated with improved or stabilized cerebral blood flow are tabulated. A tentative cerebral blood flow nomogram is shown as a potential model to possibly help predict Alzheimer's disease susceptibility.

Changes in regional cerebral blood flow following light treatment for seasonal affective disorder: responders versus nonresponders

BACKGROUND

Several brain imaging studies of antidepressant pharmacologic treatment utilizing single photon emission computed tomography (SPECT) have reported a normalization of deficits in cerebral blood flow (CBF) associated with recovery; other studies report no change, or a reduction in CBF following successful treatment. There have been no published SPECT studies of seasonal affective disorder (SAD) assessing response to light treatment in relation to changes in regional CBF (rCBF). In this study, we sought to test the hypothesis that increases in rCBF would be observed in SAD patients who responded to light treatment.

METHODS

Ten depressed patients with SAD underwent functional brain imaging studies with 99mTc-hexamethylpropyleneamine oxime SPECT before and after light treatment.

RESULTS

Relative increases in rCBF were observed in all brain regions compared to cerebellum in treatment responders, whereas nonresponders showed no change or decreases in rCBF relative to cerebellum. Significant differences in mean percentage change in rCBF between responders (n = 5) and nonresponders (n = 5) were detected in frontal and cingulate cortex, and thalamus.

CONCLUSIONS

These findings provide preliminary support for the hypothesis that an increase in rCBF is associated with recovery from depression in SAD.

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.

Pathophysiological mechanism of seasonal affective disorder

Despite the long history in medicine, the pathophysiological mechanism(s) of seasonal affective disorder (SAD) remain largely unknown. By employing a meta-analytic methodology, the authors of this study attempted to verify the validity of different pathophysiological mechanism(s) proposed for SAD. The findings showed that for phototherapy of medium light intensity, a combination of morning-evening therapy regime yielded the best therapeutic effect, and the antidepressant effect of the morning-evening light regime was superior to a single pulse of light administered at other times of day. Furthermore, the data showed that the antidepressant effect of a single pulse of light was similar for morning, midday, and evening light. These findings supported the photon-count hypothesis and refuted the proposed photoperiod, melatonin, and phase-shifting models of SAD.

Suppression of melatonin secretion by bright light in seasonal affective disorder

Eleven patients with winter seasonal affective disorder and 10 healthy controls were exposed to light of 3300 lux for 5 min and for 1 hour respectively on consecutive evenings at 22:00 hours during winter and summer. In the winter, the measurements were undertaken both before and after the treatment with bright light for 2 weeks. In the summer, there was no treatment. Melatonin concentration in saliva and subjective sleepiness were measured at 22:00 and 23:00 hours on each test. There was no significant difference in the suppression of melatonin in response to the light tests between the patients and the controls. Exposure to light reduced the level of subjective sleepiness more among the patients compared to the control subjects. This reduction was not associated with the change in melatonin secretion nor the improvement in depressive symptoms.

Melatonin in light treatment of patients with seasonal and nonseasonal depression

Melatonin as a marker of circadian rhythm and the effect of bright light on melatonin were studied in 63 depressed patients, 42 with a seasonal pattern and 21 with a nonseasonal pattern. The patients were matched for age, time of treatment and severity of depression. Before light treatment, blood was sampled for melatonin and depression was clinically rated with the Comprehensive Psychopathological Rating Scale and Hamilton Depression Rating Scale. Two hours of light treatment, 350 cd/m2, was given daily for 10 days 0600 to 0800 or 1800 to 2000. Of the 42 patients with seasonal depression, 26 were treated with morning light and, 16 with evening light. The melatonin amplitude was significantly decreased by light, and the melatonin phase position was advanced by morning light and delayed by evening light. All patients except for 3 in each group changed in the expected direction. Although the patients with seasonal pattern had a more favorable outcome than patients with nonseasonal pattern, there was no difference in therapeutic outcome related to the baseline melatonin phase position. The hypothesis that the short term clinical effects of light therapy either in the morning or evening are related to pretreatment melatonin levels or alteration of melatonin amplitude or phase position was not supported in the study. There was also no significant difference between the seasonal and nonseasonal patients related to the degree of light suppression of melatonin and the rebound effect of serum melatonin levels following bright level exposure between 2200 and 2300 before regular light treatment.

Cultured peripheral blood mononuclear leukocytes from anorexia nervosa patients are refractory to visible light

Cultured human peripheral blood mononuclear leukocytes [PBML] from patients with anorexia nervosa [AN] did not respond to light stimulation as PBML of normal controls [NC] did. During winter, visible light increased [3H]thymidine incorporation into DNA of NC-PBML stimulated with phytohemagglutinin [PHA]. This effect was enhanced by 10(-7) M melatonin. PHA-stimulated DNA synthesis of PBML from AN patients failed to respond to photic stimulation during winter, and their proliferative response to melatonin was significantly blunted. In vitro photic stimulation of NC-PBML reduced melatonin while increasing both serotonin and 5-hydroxyindole 3-acetic acid [HIAA] production in both basal and PHA-stimulated conditions. In contrast AN-PBML, that in darkness enhanced the oxidative deamination of serotonin into HIAA more than NC-PBML, did not switch their indole metabolism in response to light. Light did not inhibit the binding of both melatonin and serotonin to AN-PBML as occurred in NC-PBML. The present data suggest that AN-PBML do not respond to light in vitro, because of a failure in the regulation of serotonin and melatonin metabolism.